PLATINUM METALS REVIEW · PLATINUM METALS REVIEW ... Index to Volume 6 Communications should be addressed to The Editor, Platinum Metals Review JO~ILSOIL, ... tiow of these ceh ore

PLATINUM METALS REVIEW

A quurterly survey of reseurch o n the platinum metuls urrd of dwelopments in their applications in industry

V O L . 6 O C T O B E R 1 9 6 2

Contents

Combustion Efficiency in Gas Turbine Engines

Palladium Alloy Diffusion Cells

Rhodium as a Polymerisation Catalyst

Raney-type Platinum Metal Catalysts

Oxides of Iridium and Ruthenium

Thermal Conductivities and Electrical Resistivities of the Platinum Metals

Platinum in Telstar Satellite

Immersion Plating of Palladium

Diffusion in Platinum-clad Molybdenum

High Temperature Tensile and Creep Properties of Some Platinum Alloys

A Thermocouple for Transient Temperatures

The Story of Adams’ Catalyst

Abstracts

New Patents

Index to Volume 6

Communications should be addressed to The Editor, Platinum Metals Review

J O ~ I L S O I L , Mutthey & Co. , Limited, Hatton Garden, London, E.C.1

N O . 4

Combustion Efficiency in Gas Turbine Engines STUDY OF TEMPERATURE DISTRIBUTION WITH RHODIUM-PLATINUM THERMOCOUPLE PROBES

By P. J. Stewart Aero Engine Division, Rolls-Royce Limited, Derby

One of the many critical test-bed procedures carried out at the development stage on new or improved designs of gas turbine engines is the investigation of temperature distribution to ensure that the expansion rate of the gas flow through the flame tubes is evenly balanced throughout the engine, thus ensuring a good combustion efficiency. It is also important to ensure that the best temperature distribution is achieved for balanced power output.

In the test, use is made of specially designed thermocouple probes, constructed of 40 per cent rhodium-platinum alloy, which house fine gauge platinum: 13 per cent rhodium-platinum thermocouples. An extensive series of temperature determinations across the combustion discharge nozzle provides information from which the temperature distributions may be ascertained and vital information on the gas flow deduced.

A diagram of a gas turbine engine is shown on the opposite page.

In the simplest of terms its operation is as follows: air taken into the engine is com- pressed and passes through guide vanes into a series of flame tubes positioned round the annulus of the engine and enclosed by a combustion chamber. Fuel burners in the flame tubes burn kerosene at approximately 2o0o0C. The gas expands rapidly and forces its way through the combustion chamber where nozzle guide vanes guide the gas to the turbine blades. Here a proportion of it is converted into mechanical energy to drive the compressor (in the case of a turbo-prop engine

Improvement in design of a gas turbine engine depends to a great extent upon achieving the optimum temperature distribution across the combustion chamber. I n order to study this and so to be able to modify design a comprehensive series of temperature readings must be made across the combustion discharge nozzle. This article describes the test-bed procedure adopted by Rolls- Royce to provide the information required, the measurements being made with platinum thermocouples housed in specially designed probes. To withstand the high temperatures and pressures involved these probes are constructed in

40 per cent rhodium-platinum.

a large percentage of the gas energy is absorbed by the turbine to drive a propellor) while the rest of the gas exhausts to provide propulsion.

There are two main types of combustion systems which may be loosely described as cannular and annular. In the first case a series of cans or flame tubes is arranged around the engine with one fuel burner in each flame tube, in the latter case there is a single continuous flame tube around the engine which has a ring of burners round it.

These different systems do not affect the basic principles involved in the combustion efficiency test. The flame tubes may be constructed of high temperature Nimonic alloy,

Platinum Metals Rev., 1962, 6 (41, 126-129 126

but the temperature of the flame is so high that to avoid burn-out of the tubes it is imperative that the flame envelope should not impinge on the tube walls.

Combustion Traverse Test The temperature measurements are not carried out in the immediate flame area: no normal material ductile enough to be formed into a thermocouple probe could withstand such temperatures without involving considerable expense. The determinations are made at some distance from the flame, the usual position of immersion into the engine being around the nozzle guide vanes situated at the exit from the combustion chamber, as shown in the diagram below.

This position ensures that the temperature (1200°K to 1400'K) is not too high for the probe to withstand, bearing in mind the considerable pressure (approximately 200

p.s.i.g.) to which it is subjected, and that it is accessible through the wall of a modified casing that is used during development testing. The measurements gained in this position are used to calculate accurately temperature distribu-

tion and flame deflection. Such combustion test measurements are not carried out in flight, for once the shape of the flame is set this feature is incorporated in the basic design and is standard in all production engines.

To give sufficiently accurate cover of the selected test area and to gain a comprehensive appreciation of the temperature gradients as many as fourteen probes are used, the cross- sectional area in which readings are taken being approximately 18 x 3 inches. The probes are traversed across this area, movement in and out being by means of an electric actuator. The distance travelled into the engine by the probes is measured by a Desynn indicator and the temperature at the particular immersion is recorded on a multipoint recorder. As in each position several seconds are allowed to ensure that the sheathed thermocouple truly attains the temperature to be measured, a complete combustion traverse test can be of several days' duration. The test is normally applied simultaneously to two of whatever number of combustion chambers are present, a total of fourteen probes in all being used.

Simplijied diagram of a gas turbine engine showing the main engine construction and the position at which the probes are inserted

Platinum Metals Rev., 1962, 6 , (41, 127

Part of an engine with outer covers removed to show theJame tubes that are to be subject to the combustion traverse test. The positions of entry of the probes can be seen on the outer casing of

the engine, the probes being hidden behind the fan plate

The location within the engine of the selected chambers is not critical but two sets of readings are taken and correlated so that findings and possible design amendments are not based merely on the results from a single chamber. These results may be further correlated with those from instruments situated in the exhaust area of the engine.

From the recorded temperature measurements a chart is produced showing flame distribution and temperature gradients across the combustion chamber, an illustrative chart being shown below. The actual flame temperature can then be deduced and this is

considered in relation to the original design features. Should the flame shape be such that it impinges on the flame tube wall or is likely to result in an unbalanced power output from the engine, alternative courses of action are considered. The flame shape may be altered by adjusting the volume of cooling air that is fed into the flame tube for stabilisation, while modification of burner design, a change to a different type of burner, modification of flame tube design or a change in the type of fuel are alternatives that may be considered.

The course of action that is taken depends entirely on the type of engine involved and on

A typical 40 per cent rhodium-platinum probe manufactured for Rolls-Royce Limited by Johnson, Matthey & Co., Limited


DiSCHARGE NOZZLE T E M P E R A T U R E TRAVERSE "C

A typical chart from a combustion traverse test

the expense incurred in carrying out such a modification, and therefore no generalisations are possible in this article.

Probe Design The outer sheath of probes employed in the

combustion traverse tests carried out on the earliest jet engines, which operated at much lower temperatures than the engines of today, were made of a special grade of stainless steel or of Inconel. Subsequently 20 per cent rhodium-platinum alloy was used, but with the increasing tendency towards higher flame temperatures and higher pressures in gas turbine engine design, recourse has had to be made to 40 per cent rhodium-platinum.

This high melting point alloy (1950°C) has a good tensile strength (31 tons per square inch) a relatively high Vickers hardness (150 in the annealed state) and excellent resistance to creep above IOOO"C, this last property generally determining its use in high temperature applications.

Under test conditions the probe has to withstand exposure for a number of hours to

a temperature of approximately 1200°C and to pressures approaching 200 pounds per square inch. The sheath therefore has to have a wall thickness great enough to ensure that it can withstand the force exerted but not so thick that the response time of the thermocouple is sacrificed.

Many types and sizes of probe are employed, the actual dimensions and design being dependent to a degree on the engine design, but basic features are common to all probes. A double sheath is employed, both the inner and outer tubes being of 40 per cent rhodium-platinum and maintained parallel to each other by means of a guide washer of the same alloy. T o maintain sensitivity of response a 0.078 inch diameter hole is situated close to the sealed end of the outer tube, while the shorter inner tube has an open end. The hot gas from the flame tube is thus able to circulate within the probe and flows over the junction of the platinum: 13 per cent rhodium- platinum thermocouple, the rest of the thermocouple wires being contained in a twin-bore alumina sheath.


Palladium Alloy Diffusion Cells COMMERCIAL UNITS FOR THE PRODUCTION OF ULTRA-PURE HYDROGEN

By H. Connor, B.SC. Platinum Development Department, Johnson Matthey & Co Limited

An alloy of palladium for the diffusion of hydrogen that is dimensionally stable when thermally cycled through the alpha-beta phase transition temperature in the presence of hydrogen was discovered by the Atlantic Refining Company, Philadelphia, U.S.A. (I), and reported in this journal by J. B. Hunter (2). The principles on which the range of industrial-scale diffusion cells is based were worked out jointly by the Atlantic Refining Company and J. Bishop & Co., Malvern, Pennsylvania, an associated company of Johnson Matthey, who have world-wide rights to utilise the relevant patents (3). Since these diffusion cells were brought on to the American market just over two years ago a number of large-scale hydrogen purification plants incorporating them have been installed. Among such plants the I 15,000 cubic feet per day unit operated by the National Cylinder Gas Division of the Chemetron Corporation has recently been described (4).

Construction of Diffusion Cells While pure palladium has been known for

many years to be selectively and very highly permeable to hydrogen, an alpha-beta phase transition which occurs at temperatures below 310°C makes the metal dimensionally unstable and liable to severe distortion and failure. The addition of silver to palladium, however, inhibits this phase transition and also increases its permeability without any loss of selectivity. An alloy having a composition of 23 per cent silver : 77 per cent palladium has been found in practice to give a maximum rate of diffusion of hydrogen under

Previous articles in this journal hare described the development of polldium alloy diflwion c e h for the punfiat ion of hydrosen. A range of commercial cells has m w been mode availuble by Johnson Motthey to make possible the lurge-$cok production of ultra-pure hydrogen from hydrogen l e a pure, or from a range of industrial gases con- toining hydrogen. The, conrtrrrction. operaion, performonce and applica- tiow of these c e h ore described here.

a given set of operating conditions and is now employed as the basis of the construction of the diffusion cells described here.

In order to make the most economic use of the alloy while obtaining maximum diffusion area with a maximum of strength to withstand high differential pressures, it is employed in the form of small-diameter, thin-walled tubes. These tubes are of standard dimensions, and as the rate of diffusion of hydrogen under a given set of operating conditions is directly proportional to diffusing area the capacity of each cell is determined by the number of alloy tubes it contains.

Each alloy tube is closed at one end and has its open end extending into a manifold space. The impure hydrogen circulates over the outside surface of the tubes, but only hydrogen diffuses through their walls and is collec- ted in the manifold space from which it passes out of the cell.

The bundle of diffusion tubes is contained

Platinum Metals Rev., 1962, 6 , (41,130-135 130

, c , A I

Dimension “E”

OUTLET

UL-klREH-w A U SWNLESS / mLLylELL

Outside diameter “F”

within a stainless steel shell designed to withstand maximum internal pressures of up to 500 psig (34 atmospheres) at working temperatures up to 500°C. Connection to each cell is made by means of standard Ermeto stainless steel pressure couplings, the three couplings of each cell being the same size to ensure complete and easy interchange- ability of each cell. The general construction

0.50 in 1.27 cm

0.50 in 1.27 crn

0.69 in 1.75 cm

0.69 in 1.75 cm

I PI 1 and R

Relative performance

0.375 in 0.95 cm

0.375 in 0.95 cm

0.50 in 1.27 crn

0.50 in 1.27 cm

A.1 I I .o

A.3 I 4.3

A.5 I 9.3

A.71 16.0

ncipal Dim1 lative Perfa

Length “A”

30.13 in 76.52 cm

30.13 in 76.52 cm

30.75 in 78.1 cm

78.1 crn 30.75 in

of a cell is shown in Figs. I and 2, while dimensions of the range of cells and their relative performance ratios are given in the table below.

Operation of Cells In operation the impure hydrogen is led to

the manifold-end of the diffusion tubes by means of a central inlet tube within the shell.

nsions of Palladium ‘manee Ratios of the

lloy Diffusi ’our Cells ii

Dimension “D”

2.13 in 5.40 cm

2.13 in 5.40 cm

2.81 in 7.14 cm

2.81 in 7.14 cm

n Cells the Range


0.84 i n 2.13 cm

1.32 in 3.34 cm

1.66 in

4.22 cm

1.90 in 4.83 cm

1.09 in 2.78 cm

2.78 cm

1.16 in 2.94 cm

1.16 in 2.94 cm

I .09 in

Outside diameter

"B"

From there it flows over the outside surface of the tubes to the “bleed-off” coupling, where undiffused hydrogen together with all impurities and “inert” gases leave the cell. It has been clearly demonstrated (5, 6 ) that in order to obtain high and reproducible rates of diffusion of hydrogen, the latter must be maintained in continuous movement over the alloy surface. This ensures that impurities and diluent (“inert”) gases are continuously swept out of the cell. It also, however, reduces the proportion of the incoming hydrogen which is recovered in the ultra-pure form. For any given set of operating conditions (i.e. pressure differential across the walls of the diffusion tubes, temperature, volume-composition of the inlet gas), the rate of diffusion of hydrogen through the walls of the alloy tubes rises with increasing rate of “bleed-off” volume until it reaches a steady maximum value. This is illustrated very broadly in Fig. 3. The decrease of the percentage-recovery of the inlet hydrogen as the “bleed-off” rate increases is shown, also in broad principle, in Fig. 4.

It is thus apparent that an economic balance must be struck between a desirable high rate of diffusion and the accompanying undesirable loss of undiffused hydrogen. The manner in which such a balance is obtained depends on

(a) The partial pressure of hydrogen in

(b) The back-pressure of ultra-pure hydro-

(c) The operating temperature

the feed-gas

gen

Effect of Pressure For a fixed set of other operating variables,

the rate of diffusion of hydrogen depends on a concentration gradient, and is approximately proportional to the hydrogen partial pressure difference across the walls of the alloy tubes if this pressure difference is below about zoo psi (14 atmospheres). For partial pressure differences above 400 psi (27 atmospheres) the diffusion rate is proportional to the difference between the square roots of the

Platinum Metals Rev., 1962, 6 (41, 132

Fig. 2 A Johnson Matthey silver-palladium alloy diffusion cell, showing the ultra-pure hydrogen

outlet uppermost

high and low pressures. At intermediate partial pressure differences the diffusion rate follows the difference between the high and low pressures, each raised to the power of 0.8.

A square root pressure dependence would be expected if surface reactions could be neglected and if the hydrogen concentrations within the membrane were well below the solubility limit. Such conditions do not apply industrially, and experience has shown that the form of the pressure dependence curve generally observed is explicable largely in terms of the pressure-solubility isotherms which determine the steepness of the hydrogen concentration gradients across the membrane.

Before hydrogen can dissolve in the metal it must dissociate into atoms. This dissocia-

tion takes place only at certain “active centres”. Surface contamination limits the number of such active centres available. When an increase in hydrogen partial pressure has caused all such centres to be fully occupied a pressure rise does not contribute to the number of hydrogen atoms chemi-sorbed at the alloy surface. These surface reactions have a significant effect upon the shape of the pressure dependence curve when very thin membranes are being employed or when thicker membranes are significantly contamin- ated.

The rate of diffusion through reasonably clean membranes thicker than about 0.003 inch is, however, controlled largely by the ability of hydrogen atoms in the form of protons to permeate the metal lattice. Because of this the rate of diffusion of hydrogen is found to vary inversely as the thickness of the membrane within fairly close limits.

Effect of Temperature The rate of diffusion is markedly dependent

on the temperature of the alloy tubes. Virtually no diffusion takes place at room temperature, while increasingly rapid rates are obtained above ZOO‘C. When all other variables are kept constant, a rise from zoo to 400°C in operating temperatures causes an increase of approximately 30 per cent in the rate of diffusion, as illustrated in Fig. 5 .

An operating temperature of 350 to 400°C is recommended, and this is best obtained by pre-heating the feed-gas. A stainless steel clad chromel-alumel thermocouple is provided in each cell, and measures the temperature of the feed-gas immediately before access to the diffusion tubes is obtained. Pre-heating the feed gas is to be preferred to heating the cell by means of a tubular furnace, as the latter method is less efficient. Furnace heating requires higher element temperatures, while an unwelcome and wasteful temperature gradient would exist across the stainless steel shell of the cell. Furthermore, strong cooling effects are produced if cold feed-gas is led into a furnace-heated cell.


A cell into which preheated gas is fed must be well insulated and an electric heating tape operating at 400°C may be wrapped around the cell in order to minimise heat losses.

Installation and Performance Diffusion cells should be mounted vertically

with the ultra-pure hydrogen outlet uppermost; th i s will enable the alloy tubes to hang freely downwards within the shell. Depend- ing on the desired rates of diffusion and volumes of gas to be dealt with, two or more cells (of the same or different size) may be mounted and connected in parallel, enabling very large flow rates to be obtained.

As may be seen from the above, a number of variables affect the output of ultra-pure hydrogen of any one cell. It is not possible, therefore, to give specific outputs unless the operating conditions are also closely specified. As an example, however, it may be mentioned that one A71 cell (the largest of the range of four cells) will yield over 500 standard cubic feet (14,000 litres) per hour of ultra-pure hydrogen when using cylinder hydrogen as a feed-gas and operating at 350°C with a pressure-differential of zoo psi (13.6 atmospheres), the ultra-pure hydrogen being withdrawn at atmospheric pressure.

In order that the size, number and operating conditions of diffusion cells may be assessed for any given application, it is necessary to know the following:

(a) The volume-composition of the feed- gas

(b) The volume per hour of ultra-pure hydrogen required

(c) The economic minimum percentage- recovery of the inlet hydrogen in the form of ultra-pure gas

Purity of “Ultra-P~re~~ Hydrogen There is no evidence that any gas, other

than hydrogen, is able to diffuse through silver- palladium under the conditions generally employed for the operation of diffusion cells. Oxygen, the only commonly-encountered gas which it might be thought could diffuse,

combines catalytically with hydrogen on the surface of the alloy and the resultant water vapour does not diffuse through the metal.

The detection and quantitative estimation of impurities present in hydrogen to a concentration of less than I ppm present very considerable difficulties. It is believed that these impurities have, in fact, a concentration of about 0.1 pprn or less in the gas after diffusion, and that any such impurities detected result from leaks in the system or from out-gassing of its walls. Hydrogen purified by diffusion through palladium or silver-palladium is believed to be substantially purer than may be obtained by any other method.

Life of Diffusion Cells There are no moving parts in a diffusion

cell, which is designed to operate continuously at pressures and temperatures up to its rated maximum. Cell life, therefore, should be extremely long and only terminated by accidental mechanical failure.

In practice, however, the output from cells may progressively decline in time due to cumulative poisoning of the catalytically active surfaces of the alloy tubes. Two such forms of poisoning are recognised:

(a) ‘Termanent”, or irreversible poisoning resulting from contamination by compounds of sulphur, mercury, arsenic and certain other base metals. These poisons attack the alloy tubes in time and cause loss of diffusion rate. No quantitative estimate has been made to date of the degree of tolerance of the cells towards these poisons, but it is recommended that if known to be present their concentrations be kept down to a minimum.

(b) “Temporary”, or reversible poisoning, resulting from strong chemi-sorption of some unsaturated hydrocarbons, certain oxygen-containing compounds and higher hydrocarbons. This form of poisoning is easily rectified when a loss

Platinum Metals Rev., 1962, 6 J (41, 134

of output is observed by purging the cell with nitrogen and blowing hot filtered air through it in place of the usual feed-gas while the cell is at operating temperature.

Applications

of application : Diffusion cells have three potential fields

(I) As a means of purification to ultra-pure standards of hydrogen obtained from cylinders or other sources. In this instance the ultra-pure hydrogen is required for specialised applications, as for example in the heat-treatment of stainless steels or other metallurgical processes, or in the semiconductor or chemical industries.

(2) As a means of obtaining pure hydrogen from a cheap but low-grade hydrogen- containing gas, for example cracked

ammonia, hydrocarbon reformer gas, petroleum reformate streams or other industrial process gases.

(3) As a means of removing unwanted hydrogen from process gases.

In all these applications the diffusion process offers substantial advantages over some other possible systems, in that the cells are very compact and robust, require little attention and have a reclaim value on account of their palladium alloy content,

References I Atlantic Refining Company, U.S. Patent

2 J. B. Hunter, Platinum Metals Rev., 1960, 4,

3 Atlantic Refining Company and J. Bishop &

4 Platinum Metals Rev., 1962, 6, 47-48 5 A. S. Darling, Platinum Metals Rev., 1958, 2,

6 Johnson, Matthey & Co., Limited, British

2,773,561

130

Co., U.S. Patent 2,961,062

16-22

Patent 825,973

Rhodium as a Polymerisation Catalyst FURTHER STUDIES ON POLYBUTADIENE PREPARATION

The use of aqueous solutions of rhodium salts as stereo-specific catalysts in the polymerisation of I , 4 butadiene has recently been reported by the research laboratories of the United States Rubber Company. This development may make possible the large- scale production of cis-polybutadiene by the commonly-used technique of emulsion-polymerisation.

Further aspects of this work have now been reported from the laboratories of the Shell Development Company, Emeryville, U.S.A., by A. J. Canale, W. A. Hewett, T. M. Shryne and E. A. Youngman (Chem. & Ind., 1962, (24), 1054). These workers demonstrated that, in addition to trans-I, 4 polymerisation of butadiene possible with Rh3+ salts, a much broader steric control over such polymerisations is possible with other ions and complex compounds of the platinum group metals. Under the polymerisation conditions studied, for example, almost complete trans-I, 4 additions were obtained using rhodium trichloride, cyclo-octadiene rhodium chloride and iridium trichloride as catalysts. Palla-

dium, in the form of palladium chloride or ammonium chlorpalladate, gave high proportions of I, 2 polymerisations but the polymers had low molecular weights. One of the highest proportions of cis-I, 4 additions obtained resulted from the use of ruthenium trichloride with triphenyl phosphine or tri-n-butyl phosphine. Cobalt catalysed polymerisations, however, yielded the highest proportion of &-I, 4 polymers, and also gave the highest molecular weights.

The fact that certain compounds that normally inhibit the “classical” free radical polymerisations had no effect on the reaction studied indicates that a completely different mechanism is operative in these instances. While no specific mechanisms have been suggested to date, it is clear that the ligands, the nature of the transition metal ions and their valency states exert powerful influences on the steric course of the polymerisation, its rate and the molecular weight of the products. I t is postulated that the transition metal hydride may play a part in the initiation of some polymerisations.

Platinum Metals Rev., 1962, 6 J (41, 135-135 135

Raney-type Platinum Metal Catalysts EXTENDED-SURFACE ELECTRODES IN mJEL CELLS

The formation and numerous applications in the laboratory and on a chemical plant scale of Raney nickel have been familiar for many years. This hydrogenation catalyst is prepared by alloying nickel with aluminium and subsequently dissolving out of the resulting brittle inter-metallic compound the aluminium constituent, leaving a highly active catalyst consisting of a porous, extended- surface skeleton of nickel. The alloying process is strongly exothermic, and the brittle product must be crushed to a powder. Raney nickel is far more active as a catalyst than powdered nickel of equivalent particle-size.

During recently reported investigations on electrode structures for use in fuel cells carried out by H. Krupp, H. Rabenhorst, G. Sandstede and G. Walter of the Battelle Institute, Frankfurt, and R. McJones of the Cummins Engine Company of Columbia, Indiana (-7. Electrochem. SOC., 1962, 109, (7), 553), modified Raney-type platinum, palladium and rhodium catalysts were found to provide excellent fuel electrodes under certain conditions. To date no fully satisfactory low- temperature fuel electrode has been developed to oxidise hydrocarbons at a useful rate at temperatures below 200°C. Partially oxidised hydrocarbons such as methanol are, however, much more readily and more completely oxidised, but at least some of the reactions involved in the stepwise oxidation at the anode must be accelerated catalytically. Electrodes must therefore incorporate a suitable catalyst that above all is able to accelerate the accept- ance of electrons from the fuel by the anode. It is thought that the activity of such catalysts is related to the number of crystallographic defect structures in their surfaces and in the report under discussion Raney-type catalysts were investigated since they may be produced at room temperatures, thus avoiding re-

crystallisation enhanced at higher temperatures. Earlier work had referred to methods of construction of Raney-type electrodes and these methods were followed.

Electrode specimens were prepared in the form of porous discs by compressing a mixture of skeleton metal powder and Raney powder, followed by dissolution of the aluminium constituent. The skeleton powder in each electrode was the same as the active constituent of the Raney alloy, and the latter had an active metal concentration less than the stoichiometric I : I ratio but greater than about 20 per cent, as below this concentration the alloy became too ductile for powdering. Skeleton powder and Raney alloy were mixed in the ratio of I : I v/v and compacted into discs under high pressures with the incorporation of two platinum screens to increase their mechanical strength. The aluminium was dissolved out first by dilute, then by concentrated, caustic potash solutions at temperatures up to 80°C. Complete removal of aluminium is not possible, but further dissolution of this metal was obtained anodically.

The electrodes were evaluated using caustic potash, potassium carbonate and sulphuric acid as electrolytes. Hydrogen and methanol were employed as fuels, and the noble metal electrode performances were compared with those of copper, cobalt and nickel.

With hydrogen in KOH electrolyte, all electrodes reached the reversible hydrogen potential on open circuit, with platinum giving the least polarisation. With platinum, palladium and rhodium electrodes current densities obtainable exceeded 500 mA 'cmB and 300 mA/cm2 respectively, when using hydrogen and methanol as fuels, and limiting current densities were not determined. Since

Platirzum Metals Reu., 1962, 6 9 (41, 136-137 136

the results obtained with nickel electrodes were found to be inferior to those reported in earlier work, it was concluded that all electrodes investigated might have been improved by the use of better powder metallurgical techniques.

With methanol in KOH electrolyte, palladium provided the best results, platinum and rhodium following in decreasing order of performance. With methanol in acid solution platinum was found to be most active. In all cases, activity was considerably reduced when potassium carbonate solutions were employed as electrolyte. Copper and cobalt were not considered to be satisfactory catalysts for methanol or hydrogen electrodes. It was also found that sintering the noble metal electrodes destroys their activity with methanol and seriously affects it for use with hydrogen.

A laboratory-scale fuel cell using a palladium fuel electrode, a silver oxygen electrode and a gN solution of KOH as electrolyte, was employed to examine the degree of conversion of methanol. The conclusion was formed that even at room temperature methanol oxidation proceeds almost completely to carbonate or carbon dioxide.

When formaldehyde and formic acid were investigated as possible fuels, large current densities were obtained with polarisations comparable with those observed for methanol. Similar results were found in alkaline and acid electrolytes, although somewhat higher fuel conversion efficiencies were obtained in the latter. No appreciable electrochemical oxidation was found under the experimental conditions employed when hexane or methylcyclohexane were tried as fuels. H. C.

Oxides of Iridium and Ruthenium NEW VALUES FOR OXYGEN PRESSURES OF FORMATION

In his review of the thermodynamics of the gaseous oxides of the platinum metals, C. B. Alcock (Platinum Metals Rev., 1961, 5, 134) referred to the work of Schafer and his collaborators on the oxides of iridium and ruthenium. Some further experimental work has now been reported by G. Schneidereith in the course of a dissertation from the Harald Schiifer Institute of Miinster, West- phalia.

Schiifer and his co-workers had previously found that coarse crystals of IrO, and RuO, were produced by heating the metals in a stream of oxygen (760 torr) to 1150 and 1270'C respectively. Both metals form volatile trioxides which, in contact with the colder walls of the quartz vessel, decompose to rough single crystals of blue-black IrO, and black RuO,. The oxygen pressures of formation of these dioxides have been determined by Schneidereith by different methods and compared with the numerical values given by Alcock. Some of the values reported are set out in the table.

Solid IrO, dissolves less than 5 atomic per cent of iridium. The enthalphy of formation ~H(298)-calculated from the elements-amounts to - 5 2 . 4 ~ Kcal for

Oxygen-pressures p in torr for reactions IrO,+Ir -,L 0, and RuO,+Ru + Oz

at temperatures t in O C

t

900 950

I000 I050 I roo I I24 I I50 I200 I250 I300

p for IrO,

34 76

I54 316 572 760

I020 - - -

p for RuO,

- - - -

1.5. .4.5 -2

3.3. ,6.9 6.7.. 12 13.2. .23 -25

IrO, and to -68.1 Kcal for RuO,. The resistivities of single crystals of IrO, and RuO, at 22OC were found to be 48 microhm- cm and 50 microhm-cm respectively. The temperature coefficients between -78 and +2z°C were approximately +o.o008 for IrO, and $0.00075 for RuO,.

0. L.

Platinum Metals Rev., 1962, 6 9 (41, 137-137 137

Thermal Conductivities and Electrical Resistivities of the Platinum Metals By R. W. Powell, Dsc., Ph.D., F.Inst.P., R . P. Tye and Margaret J. Woodman Basic Physics Division, National Physical Laboratory, Teddington

New values are presented and discussed for the thermal conductivities and electrical resistivities of ruthenium, osmium, rhodium, iridium, palladium and platinum over the approximate temperature range 80" to 500°K.

It became apparent during a recent revision by one of the authors of the thermal conductivity section of Kaye & Laby's well-known book of tables of physical constants that the values hitherto quoted for the thermal conductivity of some metals, and in particular of rhodium and iridium, were clearly in error.

When the previously reported data were examined it was found that the values of the Lorenz number (thermal conductivity multi- plied by electrical resistivity divided by the absolute temperature) gave unusually low values for these metals, and investigations were put in hand to make new determinations of thermal conductivity and electrical resistivity. The new values found for iridium and rhodium have already been reported (I) and it may be noted that at room temperature the value of thermal conductivity for iridium is greater than the value previously quoted by a factor of about 2.5 and that for rhodium by about 1.7.

Of the four metals of the platinum group yet to be considered, no thermal conductivity values appear to have been measured at normal temperatures or higher for osmium and ruthenium, those for palladium in the range oo to 100°C (2,3,4) show differences of up to 27 per cent, and, whereas most available values for platinum show closer agreement in this temperature range (2, 4, 5, 6, 7), differ-

ences of about 30 per cent occur between the fewer measurements made at IOOO'C (8, 9,

The thermal conductivities of osmium and ruthenium have been measured by White and Woods (11), but only below 150°K. These workers note that extrapolation of their thermal data suggest a thermal conductivity at room temperature of about 0.9Ao.1 W cm-ldegl for osmium and about 1.1 50.1 W cm-ldegl for ruthenium. They at the same time make a plea for accurate determinations of the thermal conductivity at 300" or 400°K to be made.

Specimen Details The specimens studied in this work were

all supplied by Johnson, Matthey & Co., Limited, in the form of small rods having the dimensions given in Table I. This table also contains values of the density and such details as were supplied regarding chemical impurities and the method of preparation.

Experimental Methods and Results The experimental methods used have been

similar to those described previously (I, 12).

An electrical resistivity determination was first made at room temperature with the samples resting on knife edges at a fixed distance apart and serving as potential con-

10).

Platinum Metals Rev., 1962, 6 , (41, 138-143 138

Table I

Details of Specimens I Impurities per cent

.ooo:

Densit)

glml - 12.36

22.45

12.44

22.43

12.02

21 .s I

Length

Metal cm Dia.

0.660

0.489

0.318

0.636 .COO!

0.635

- c u

- lr -

-03 to .I

- Ag

.ooo I

.OM1

.OD5

:.ooc

- Fe

.o I

.0005

.M)5

.0005

.0001

.oo I

.0002

.om I

.0001

Rhodium

Palladium

.oo I to

.005

tacts. The resistivity obtained by comparing this potential drop with that across a standard resistance was later used to give the effective shape factor, ratio of area to length, when thermocouples fixed to the rods served to measure the temperature and also as potential leads.

Determinations of electrical resistivity were made in this way to high temperatures and down to liquid nitrogen temperatures.

for iridium and platinum is this ratio lowest in the samples used for the present work.

Curves showing the variation of electrical resistivity with temperature for each metal over the range so far studied are given in the lower portion of Fig. I .

The upper portion of this figure reproduces on an enlarged scale the mean curves for the lower range of temperatures investigated. For palladium and platinum, however, the

For resistivity measurements at liquid helium temperatures a com- parison method was used in which the potential drops operated in opposition through a galvanometer, and the currents in the standard resistance and the specimen circuits were adjusted to give no deflection.

The electrical resistivity values obtained at the liquid helium, p o , and ice temperatures, pa,3, and the ratio of these two resistivities, p , , / ~ ~ , ~ , are given in Table 11. This table includes some of the results of other workers. The residual resistance ratio given in the last column can frequently be taken as an indication of the state of purity of the sample, the ratio becoming lower as the purity is increased or the state of strain decreased. Only

- 2 0 0 -100 0 100 2 0 0 300 r 201

6 0 - I I 0

5 5 0 - u 4 0 - -

1

,204 Pd 8 Pt //

> F = - , 2 0 0 400 6 0 0 800 1000 1200 I4 -200 0 3

TEMPERATURE OC

Fig. 1 Variation of electrical resistivity vf the platinum metals with temperature


2.5

1.7

5 .O

5.0

6. I

6. I

A r g o n - a r c melted and ~

ground

Annealed at -IOOo"C

Ruthenium

Osmium

Rhodium

Iridium . . Palladium

Platinum . .

Other Information

Table il Electrical Resistivity, microhm cm2/cm, measured at Liquid Helium, po and Ice Temperatures, p2,3

Metal Observer Specimen Details Electrical Resistivity

p273 Po ~O3P0lP273

Ruthenium Present work . . . . As received . . . . . . 7.13 0.566 79.4 Meissner & Voigt (I 5) . . - . . . . . . - - 8.3 Justi (16) . . . . 99.99%: sintered 2200°C .. 7.157 0.501 70 Hulm & Goodman (17) . . . . . . . . - 60 White & Woods (I I) .. Arc-melted Ru2 . . . . 7.9* 0.235 30*

,, ,, Ru3 . . . . 6.8* 0.02 3*

-

Osmium Present work . . . . As received . . . . . . 8.532 0.272 32 After heating t o 1540°C . . 8.12 0.244 30

Hulm & Goodman (17) . . . . . . . . - 40 White & Woods (I I). . Arc-melted Os2 . . . . 8.5* 0.0996 I1.7*

,, ,, Os3 . . . . 8.5* 0.0873 10.3*

-

Rhodium Present work . . . . After heating t o 1336°C .. 4.33 0.024 5.5 Meissner & Voigt (I 5) - . . . . . . . . - - 3.0 White 81 Woods (18) . . J.M., annealed 1300°C . . 4.4* 0.0084 1.9* Kemp et ol (19) Sample No. I of Gruneisen

& Goens (20) . . . . 4.63* 0.0155 3.3* . .

Iridium Present work . . . . After heating to 1310°C .. 4.71 0.055 11.7 Meissner & Voigt ( I 5) . . - . . . . . . . . - - 47.7 White & Woods (18) . . J.M., annealed 1300°C . . 4.75* 0.1034 21.8*

Palladium Present work . . . . As received . . . . . . 9.93 0.144 14.5 Meissner & Voigt (I 5) . . - . . . . . . . . - 35.3 - Kemp et ol (21) .. Annealed at 450°C . . . . 9.9* 0.0182 1.8* MacDonald e t al (22) . . Prepared by J.M., 0.031 yo - - 14.3*

impurity

Platinum Present work . . . . As received . . . . . . 9.85 0.013 1.3 Meissner & Voigt (15) . . - . . . . . . . . - I .6 White& Woods(l8) .. Annealed 1050°C . . . . 9.6* 0.0125 1.3*

-

MacDonald et ol(22) .. Prepared by J.M. . . . . - - 4.3*

* Adjusted t o 273"K, from published value

curves are still too close to be shown separately and for these metals some of the experimental points are shown.

For the thermal conductivity measurements, four versions of the longitudinal heat flow method have been used. Over the ap-

proximate temperature range of 50" to 250OC

the following variants of the guarded com- parative heat-flow method have been used, but all with water cooling at the lower end, so providing an additional absolute measure of the heat out-flow from the specimen:


Moderate Temperature Method I: The test specimen was joined to the top of

a rod of Armco iron of known thermal conductivity, water cooled at its base. Measure- ments of the heat out-flow from the test specimen were obtained in terms of the gradient of temperature in the iron and by the water- flow calorimeter. This method was used for iridium and rhodium.

Moderate Temperature Method 11: In this variant, the rod of Armco iron was

uppermost and the water-flow calorimeter attached to the lower end of the test specimen. Hence, the heat in-flow to the test specimen was measured in terms of the temperature gradient established in the iron and the heat out-flow by means of the water-flow calorimeter. This method was used for iridium, rhodium, palladium and platinum.

Moderate Temperature Method 111: For the two shortest specimens it was

necessary to join on another rod on which the heating unit could be wound. A rod of Armco iron was used for this purpose, of sufficient length to enable a measurement of the heat in-flow to be made in terms of the gradient of temperature established in a portion of this rod. The heat out-flow was derived both from the gradient in another Armco iron rod attached to the lower end of the specimen and by the water-flow calorimeter at the base of this iron rod. This method was used for osmium and ruthenium.

All joints were made by means of shrunk fits into small steel collars. The interspace between the composite central rod and the guard tube was packed with a thermal insu- lating powder having a thermal conductivity of about 0.00033 J cm/cm2 sec deg C. After corrections had been made for any imperfectly matched conditions the various heat-flow measurements usually agreed to within some 2 per cent.

Low Temperature Method

Determinations were made with the


specimen attached to the base of an internally polished metal container which could be continuously evacuated through a thin-walled cupro-nickel tube. The container was im- mersed in turn in boiling water, melting ice, crushed solid carbon dioxide, liquid oxygen or liquid nitrogen during an experiment. A heating coil was wound on the top of the specimen and was covered with a wrapping of aluminium foil. The energy supplied to this heater was measured, corrected for lead conduction, and used to determine the heat flow in the working section of the rod. Corrections for radiation transfer were derived from a second series of experiments made at comparable mean temperatures but with the specimen freely suspended in the enclosure.

Of the present group of metals, this method has been used only for iridium and rhodium. It should be noted, however, that the method has also been applied to Armco iron (13) and to rhenium (14) and has yielded values in good accord with those of other workers.

Ru-

0 s - Pd- P t L

> 400 0 I 0 0 260 3 0 0 TEMPERATURE 'C

Fig. 2 Variation of thermal conductivity with temperature

Fig. 2 depicts the variation of thermal conductivity with temperature by means of smooth curves or straight lincs that have been drawn through similar sets of experimental points for each metal.

The curves for iridium and rhodium differ a little from the results previously published by the authors (I), particularly at the lowest temperatures. This is due to use of a revised calibration for the nickel- chromium and Constantan thermocouples used.

The values of the pairs of metals belonging to the same sub-groups, ruthenium and osmium, rhodium and iridum and palladium and platinum, tend to come together.

Above normal temperature, the thermal conductivities of each metal

3.0

Y

u 0 W a 2.5

Y LD \

0 f 7 2.0

m c W

I z 1.5

W d s x

m

1.0 G!

/ \ R u

THEORETICAL VALUE

are relatively constant. The values for ruthenium agree well with the predicted value of White and Woods (11) mentioned earlier, while that for osmium lies at the lower limit of the range of values which they gave.

Curves showing the dependence of the Lorenz number on temperature are repro- duced in Fig. 3. I t is of interest to note that over the range from 323" to 500°K the Lorenz numbers of the metals of the platinum group exceed the theoretical value by amounts ranging only from o to 15 per cent. I t would seem that by using a value of 2.6 x 10-8 J ohm/ sec deg C "K it should be possible to calculate their thermal conductivities at higher temperatures from the electrical resistivity values, and to achieve an accuracy of well within 10

per cent. This order of accuracy is good when compared with the wide differences between available data, as indicated in the introduction. This conclusion raises doubts regarding the reliability of published values in the higher temperature range for the thermal conductivity of platinum (8, 10) and the Lorenz number of platinum (23) and palladium (24). For instance, the data of Holm and Stormer give Lorenz numbers

Platinum Metals Rev., 1962, 6 , (41,

73 173 27 3 37 3 473 573'K -200 -100 0 I00 2 0 0 .3OO0C

T E M P E R A T U R E

Fig. 3 Variation of the Lorenz number Zcith temperature

which increase from 2.6 x I O - ~ at about 100°C to 3.0 x 10-8 at about IOOO~C, while Hopkins (23) and Hopkins and Griffiths (24) obtain values of rather above 3 x 10-* for platinum and palladium between 1000°C and their melting points.

As the temperature is reduced towards and below the characteristic temperature, 8, the relaxation times associated with electric and thermal electronic transport are no longer comparable, hence the observed decrease towards lower values for the Lorenz number that commences in the range 300" to 400°K. At temperatures exceeding 8, where the theoretical value of the Lorenz number should hold, any excess above the theoretical value can bc attributed to augmentation of the thermal conductivity by phonon or lattice conduction.

Derived values for this lattice component have the numerically highest values of about 0.13 J cm/cm2 sec deg C for the samples of iridium and ruthenium. In general the lattice component shows a small decrease with increase in temperature and supports the doubts already expressed regarding the high temperature data for platinum and palladium.

142

Acknowledgments The authors are indebted to Mr. H. E.

Bennett of Johnson, Matthey & Co. , Limited who arranged for the loan of the various samples. Mrs. J. A. Weston made the electrical resisitivity measurements at liquid helium temperature. The work has formed part of the research programme of the Basic Physics Division of the National Physical Laboratory and this paper is published by permission of the Director of the Laboratory.

References I K. W. Powell and R. P. Tye, Proc. 9th Inter-

national Congress of Refrigeration, 1955, I, 2149

2 T. Barrett and R. M. Winter, Proc. Phys. SOC., 1914, 26, 347; Ann. Physik, 1925, 77, I

3 E. Sedstrom, 1924, Dissertation, Stockholm 4 W. Jaeger and H. Diesselhorst, Abh. d . Phys.

5 J. H. Gray, 1895, Phil. Trans. ( A ) , 186, 165 6 W. Meissner, Ann. Physik, 1915, 47, 1001 7 W. G. Kannuluik and E. H. Carmen, Aus-

8 R. Holm and R. Stormer, Wiss. Veeroflent1

g K. S . Krishnan and C. S. Jain, Brit. J. App.

Tech. Reichsanstalt, 1900, 3, 269

tralian J. Sci. Res., 1951, 4, 303

Siemens-Konzern, 1930, 312

PhYs., 19-54> 5,426

10 K. H. Bode, “Progress in International Research on Thermodynamic andTransport Properties”, A.S.M.E., 1962, 481

11 G. K. White and S . B. Woods, CanadianJ. of Physics, 1958,36,875

12 R. W. Powell and R. P. Tye, The Engineer,

13 R. W. Powell, M. J. Hic%an, R. P..Tye and Miss M. J. Woodman, Progress in Inter- national Research on Thermodynamic and Transport Properties”, A.S.M.E., 1962,466

14 R. W. Powell, R. P. Tye and Miss M. J. Woodman. In course of publication.

15 W. Meissner and B. Voigt, Ann. Physik, 1930, 7,892

16 E. Justi, Z.f.Naturforsch., I949,4a, 472 17 J, K. Hulm and B. B. Goodman, Phys. Rev.,

1957~106,659 18 G. K. White and S . B. Woods, CanadianJ. of

19 W. R. G. Kemp, P. G. Klemens and R. J.

20 E. Griineisen and E. Goens, Z . Phys., 1927,

21 W. R. G. Kemp, P. G. Klemens, A. K. Sreedhar and G. K. White, Phil. Mag., 1955, 46,811

22 D. K. C. MacDonald, W. B. Pearson and I. M. Templeton, Proc. Roy. Soc., A., 1962, 266, 161

1960,209, 729

PhYS-, 19571 35, 248

Tainsh, Annalen der Physik, 1959, 5, 35

44, 615

23 M. R. Hopkins, Phys. Zeit., 1957,147, 148 24 M. R. Hopkins and R. L. Grfiths, Phys. Zeir.,

1958, Iso, 325

PLAT1 N U M I N TELSTAR SATELLITE In J u l y this year the experimental

Telstar communications satellite, designed and constructed by the Bell Telephone Laboratories, was success- fu l ly launched a t Cape Canaveral. Roughly spherical i n shape, with a faceted surface, the satellite is 34; inches in diameter and weighs about 170 pounds.

This satellite carries equipment not only for broadband microwave communications in space bu t also for obtaining and transmitting information on its own performance and on the nature of the space environment. Power for its electronic circuits is supplied by rechargeable nickel- cadmium cells which are charged by 3,600 solar cells mounted on 60 of the 72 facets of the satellite shell. Each solar cell is mounted on a ceramic base and is covered by a transparent wafer of synthetic sapphire held i n place by a framework of platinum.

The materials for the solar cell assemblies have been selected because of their durability in the space environment and their similar properties of expansion and contraction with changes of temperature. I t is expected t h a t the bonded assemblies will remain intact for many years, t h u s enabling the satellite to carry out its programme of investigation.


Immersion Plating of Palladium AN ECONOMIC PROCESS FOR THE DEPOSITION OF THIN TARNISH-RESISTANT COATINGS

By J. E. Philpott, B.s~. Industrial Division, Johnson Matthey & Co Limited

The advantages gained from the inert properties of electrodeposited coatings of the platinum group metals as a means of providing tarnish protection on silver and base metals have for long been recognised and their use-particularly in the case of rhodium -has become widely established. Electro- deposited platinum and palladium have also been successfully employed in the tele- communications industry and elsewhere.

With the development of printed circuits, however, a need has arisen for a non- electrolytic method of deposition of these metals, more particularly because of the difficulties in making electrical connections to isolated parts of such circuits.

Palladium, with its comparatively low cost per unit weight and relatively low density, is easily the least expensive of the platinum group metals and is only about half as expensive as gold. The immersion palladium plating process described here combines this low cost with the most economic method of obtaining a thin tarnish-resistant coating. This non-electrolytic method merely involves the immersion of the part to be coated in the palladium solution.

The development of an immersion palladium solution followed from the examination of the dinitrito-sulphato complexes of the platinum metals. One of these compounds, designated DNS Platinum, has already been reported to provide a much improved electrolytic platinum plating solution which is now in commercial use. (N. Hopkin and L. F. Wilson, Platinum Metals Rev., 1960, 4, 56).

The DNS Immersion Palladium bath is based on a solution of the complex dinitritosulphato-palladous acid, H,Pd(N0,),S04, and patent applications covering solutions of this type have been filed in a number of countries.

The terminology covering metallic deposition from aqueous solutions without the use of an external e.m.f. is not yet clearly defined. The process described here is, however, based on the simple mechanism of chemical replacement. The favourable position in the electrochemical series occupied by the platinum group metals is of particular advantage in a process of this type. Moreover, this type of bath offers a number of advantages: it demands the minimum of chemical control and special skill, deposition ceases once the maximum thickness has been applied, and the risk of a costly error due to the production of inordinately thick deposits is eliminated. Indiscriminate deposition, inevitable with simple chemical reduction techniques, does not occur.

Method of Use In keeping with the nature of the palladium

deposition technique, the pre-treatment processes are all non-electrolytic. As with electrolytic deposition, however, the parts must be clean and free from grease before the immersion coating is applied. With large components, or large numbers of small components, the degreasing stage is best carried out either by immersion in hot trichlorethylene or by suspension in the vapour formed above the boiling solution.


This stage is followed by immersion in hot caustic soda and by rinsing in de-ionised water, prior to immersion in the DNS palladium solution. With printed circuits these techniques are generally too drastic, and scouring with white chalk or pumice powder will degrease and remove any oxide film from the copper tracks. Rinsing in de- ionised water is recommended before immersion in the palladium solution, which can be contained in glass or polythene vessels.

When small numbers of intricate parts are to be coated it is advantageous to stir the components with a glass rod to make sure that all surfaces are covered by a film of

solution. For larger quantities, the solution is suitable for use in a plating barrel.

Masking of areas that do not require plating can be carried out using a chlorinated rubber paint, but the extra costs involved in this procedure rarely make it economic.

The DNS palladium immersion solution is supplied as a concentrate and needs merely to be diluted with de-ionised water to a concentration of 10 g/1 to form the plating bath.

Rate of Deposition This solution will give thin replacement

deposits on many basis metals, but the rate of deposition depends on several factors.


The farther the base metal is from palladium in the electrochemical series, the faster will be the deposition rate, as is to be expected from the chemical replacement mechanism. The concentration of palladium in the solution will also affect the deposition rate; this is illustrated in Fig. I .

Variation of deposition rate with temperature is shown in Fig. 2. It will be seen that the variation over the temperature range 30" to 70°C is not of any significance. In fact for all practical purposes the bath can be worked successfully at room temperature.

As deposition proceeds, less basis metal is exposed and the rate of deposition falls. Thus the rate of deposition is an inverse function of thickness of metal already deposited.

Replenishment of the immersion solution is not worth while because of the inevitable build-up of contaminants while the bath is in operation. The 10 g/l solution can be economically worked until the plating rate has fallen by half, by which time 90 per cent of the palladium has been deposited. The table shows the amount of metal deposited on various basis materials, from a fresh solution, in 30 minutes at room temperature.

Properties of the Deposit As is typical of replacement deposits, that

obtained from DNS electroless palladium

Thickness of Palladium Deposited in 30 Minutes

Thickness of Deposit

Basis Metal

Copper .. Beryllium copper Brass . . . . Phosphor bronze Fine silver . , Standard silver Nickel-silver . . Mild steel . .

mgm per sq. inch

I .oo 2.02 2.00 I .5 1.15 I . 3 I .5 2.6

inch

0.00005 0.0000 I I 0.0000 I I 0.000008 0.000006 0.000007 0.000008 0.0000 I4


is not completely pore-free and cannot therefore be considered to give indefinite protection from corrosion. It does, however, provide a surprisingly high order of tarnish resistance.

Silver contacts, immersion plated with palladium, have remained untarnished for several months in an atmosphere that produced a tarnish film on unprotected silver within two weeks. The solderability of immersion palladium coated printed circuits was unimpaired after prolonged exposure in a similar atmosphere.

Provided that the basis metal is itself bright, the palladium deposited will also be bright and lustrous. Adhesion of the deposit is excellent.

In producing a deposit by a replacement mechanism no measurable change is observed in the dimensions of the object plated. This is of particular advantage in plating flush- bonded printed circuits. Since the deposit is thin there is insufficient stress built up in it to cause mechanical trouble due to cracking and exfoliation, yet it is sufficiently hard to provide a durable film. Unlike gold, palladium does not exhibit the high rate of diffusion into certain base metals and surface contamination from this cause does not occur.

Applications Several important applications are en-

visaged. Because the deposit is readily solderable-even after prolonged storage- it is of considerable interest in the printed circuit field. In this type of application it can be used either as a tarnish-inhibiting process to facilitate soldering after storage or as a means of improving contact performance.

It is also of use as a general tarnish- inhibitor for metal components; because it will deposit readily on silver it may be applied to silver contacts to prevent tarnishing between assembly and commissioning, without the need to remove the deposit when the equipment goes into service. It may also find use on base metal contacts in tele- communications engineering.

Diffusion in Platinum-elad Molybdenum LIMITATIONS ON HIGH-TEMPERATURE APPLICATIONS

Platinum-clad molybdenum has for long been of interest in the glass industry and, in a rather more restricted field, as a material of construction for the grids of thermionic valves. In the glass industry, platinum coatings are found to impart limited but useful protection from oxidation to molybdenum stirrer rods, electrodes and mandrels, and thus make it possible to take advantage of the high strength of molybdenum at temperatures up to 1300°C or more. In thermionic valves, the platinum coatings provide, on the strong grid supports, a surface having a high electron work function.

In both these applications, the useful life at high temperatures may be limited as a result of diffusion between the platinum and the molybdenum. An X-ray study of the phases present in the alloy layer formed during diffusion was reported in an anonymous article by the staff of the General Electric Company in 1959 (I), but this appears to have received little attention and is not quoted in a more recent metallographic study by K. Kirner, of the Max-Planck Institute for Metal Research, Stuttgart (2).

The earlier work was restricted to relatively short heating periods at temperatures up to 1300OC. Kirner has heated specimens for periods up to 500 hours at 1400°C and claims to have observed a previously unknown phase in alloys in the molybdenum-rich part of the system. This phase is only stable over 1400OC and is termed the 3 phase. It is very hard, the Reichert microhardness instrument recording a value of 1000 kg/mm2 HV,, on the phase formed in argon-arc melted alloys annealed for IOO hours at 140oOC. The phase decomposes after annealing at 1200'C for 30 hours. These results indicate that earlier work

by Raub and others on the equilibrium diagram is incomplete and further theoretical work would thus be welcome.

Kirner includes in his paper a large number of microhardness traces across diffusion bonds, both in molybdenum rods sprayed with platinum coatings and in pressure-welded cylinders. The total width of the dif- fused zone was found to grow according to a dt law.

The sprayed-on coatings, applied by an argon-plasma spray, formed a good joint after vacuum annealing and were dense, with only very few visible inclusions. Adhesion, however, was poor before annealing. They afforded good protection at temperatures up to 12oo0C, but above 1400°C the brittle q phase which is formed tended to cause coatings to peel. The formation of this phase might, however, be inhibited by interposing a layer of stable refractory, such as alumina, between the two metals.

A new approach, found to be suitable for electronic applications, has recently been suggested by the Brown Boveri company (3). This is to apply an electrodeposited coating of rhenium to the molybdenum to act as a barrier layer, adhesion of the rhenium to the molybdenum being accomplished by annealing in hydrogen or in vacuum at a high temperature. I t is implied that no alloying occurs between rhenium, which melts at 3167'C, and platinum at temperatures below the melting point of platinum.

J. C. C.

References I Anon. . . GECJournaZ, 1959, 26, (I /2), 82 2 K. Kirner Metall, 1962, 16, (7), 672 3 M. Dedk Brown Boveri Rev., 1961,48, (7),

394


High Temperature Tensile and Creep Properties of Some Platinum Alloys EFFECTS OF ADDITIONS OF PALLADIUM

Some time ago Dr. G. Reinacher of the Degussa Research Laboratories reported (I, 2)

that pure platinum and platinum alloyed with 4 per cent of palladium were more ductile than rhodium-platinum alloys between 700' and IIOOOC. In a recent paper (3) he describes the results of experiments designed to confirm these observations and to assist in the development of higher strength alloys that are more ductile than rhodium-platinum in the intermediate temperature range. The compositions of the three palladium-bearing alloys selected for testing were well within the solid solution range and the alloys were not likely, therefore, to be subject to the intermediate temperature brittleness which has previously been tentatively associated by the author with precipitation under the influence of a tensile stress.

The specimens were tested in the form of wire 2 mm diameter and the elongation at fracture was determined over a 50 mm gauge length.

The tests were carried out in air. Some

of the more important results are tabulated below.

These values show that a 5 per cent addition of palladium can be made to a 5 per cent rhodium-platinum alloy without loss of high temperature strength and with a slight improvement in ductility at temperatures up to 1250'C. Palladium additions of 10 per cent have an adverse effect upon both strength and ductility. Although the alloy containing 7 per cent of rhodium and 3 per cent of palladium has fairly good compromise properties, its strength and ductility at 1500°C are very much inferior to those of the simple 10 per cent rhodium-platinum alloy. Micro- scopic examination showed that all the palladium bearing alloys exhibited inter- crystalline cracking when creep tested at goo"C. This cracking did not occur in the alloys containing 3 and 5 per cent of palladium tested at 125oOC although the 10 per cent palladium alloy exhibited this type of failure even at 15ooOC.

Included in the table are some results for

f,,, == stress in pounds per sq. inch for a 100 hour life e = elongation per cent at fracture on a 50 mm gauge length


900 I200 4 2480 2% 2240 25 I250 I70 2 838 88 738 24

- 326 66 34 I 59 I500 -

Temp 7% Rh 3% Pd 5% Rh 10% Rh - e% f i00 e% f100 e% "C fl,,

900 3540 50 2480 18 3900 22 I250 I020 72 808 62 I I05 59 I500 34 I 39 34 I 71 483 66

Pure Pd 5% Rh 5% Pd 5% Rh 10% Pd "C flu0 e% I f100 e% e%

pure palladium taken from another recent paper by the same author (4). Here Dr. Reinacher discloses the existence of a ductility maximum in pure palladium at 500°C. Elongations of the order of 95 per cent were observed when palladium was tensile tested at 500°C. At 400 and 600°C the elongation values were only 30 per cent. Similar effects were observed during creep testing, the elongations at 500°C ranging from 95 per cent for failure in 5 hours to 40 per cent for failure in IOO hours. At 700"C, however, the greatest elongation reported was about 23 per cent. This decline in ductility with time and temperature above 500°C was shown to be caused by oxidation which spread from the surface layers and caused tearing at the grain boundaries. Above 870°C, the dissociation pressure of the oxide, strings of fine porosity developed along the grain boundaries.

These results explain the poor creep properties of palladium, but are not easily reconcilable with the observations of the ternary alloy research. It is conceivable that palladium facilitates the entry of oxygen into rhodium-platinum alloys but the effect only becomes appreciable when 10 per cent of

palladium is present and when the temperatures exceed 1250°C. Any advantages resulting from the addition of palladium to rhodium-platinum alloys appear to be marg- inal, and only apparent over a limited temperature range. Outside this range the effects are detrimental. The results of some recent American investigations (5) indicate that platinum alloys containing up to 40 per cent of rhodium display high strength and appreciable ductility at 927°C. At 1450°C this alloy was able to withstand a stress of 800 pounds per square inch for IOO hours. Limitations of the apparatus did not permit of elongation measurements at this temperature. These three researches do, in fact, confirm that no alloys having high temperature properties superior to those based on the rhodium-platinum system have yet been

References I G. Reinacher, Metall, 1958, 12, 622-628 2 G. Reinacher, Metall, 1961, 15, 657-665 3 G. Reinacher, Metall, 2962, 16, 662-668 4 G. Reinacher, Z. Metallkde., 1962,53,444-449 5 E. P. Sadowski, H. J. Albert, D. J. Accinno

and J. S . Hill, Refractory Metals and Alloys, A.I.M.E., Met. SOC. Conferences, Vol. 11, Detroit, May 25th-26th, 1960

developed. A. S. D.

A Thermocouple for Transient Temperatures RELIABILITY OF SPRING-LOADED OPEN-CONTACT PROBE

In the investigation of materials for use in the construction of missiles and spacecraft, accurate methods of measuring high transient surface temperatures are essential. At the Lockheed Missiles & Space Company a spring-loaded open-contact thermocouple probe has been developed and its design and performance are described by P. M. Hahn in a recent paper (Materials Research and Standards, 1962,2, (9,403-404).

Initial tests were made with a spring- loaded tantalum-sheathed platinum : 13 per cent rhodium-platinum thermocouple and a hammer-welded platinum : 13 per cent rhodium-platinum thermocouple in the measurement of surface temperatures of molybdenum and copper discs inch thick. Results obtained showed that the response of this spring-loaded thermocouple was too

slow for accurate measurement of rapidly increasing temperatures. A new type of open-contact probe for the spring-loaded thermocouple was then designed. In this, the thermocouple wires, 0.010 inch diameter, are insulated by an 0.071 inch diameter ceramic tube which is itself sheathed with stainless steel 0.012 inch thick. An air gap separates the spherical tips of the thermocouple wires, the material under examination serving as a common conductor. Tests using this open- contact thermocouple with spring loads of 2 to 4 pounds on heated copper and molybdenum discs gave results in excellent agreement with those obtained with the hammer-welded thermocouple. Accuracy was maintained with temperature increases of up to 800°C per second and with temperatures in excess of r20o0C.

Platirzum Metals Reu., 1962, 6 , (41, 149-149 149

The Story of Adams’ Catalyst PLATINUM OXIDE IN CATALYTIC REDUCTIONS

Among both users and manufacturers of catalysts the expression “Adams’ Catalyst” has been in common usage for many years. I t is, in fact, virtually a household term throughout the field of organic chemistry, whether on a research or an industrial scale. The story of its development, of the remarkable man who was first responsible for its preparation just forty years ago, and who at once realised clearly its potentialities in catalytic reductions, forms an interesting chapter in the more recent history of chemistry.

For a number of years before the First World War the liquid-phase reduction of. organic compounds had been achieved with the aid of colloidal platinum or palladium, or with the so-called platinum black, a finely divided form of the metal containing an uncertain quantity of oxygen. While the colloidal catalysts were rather more active, they were limited in their use owing to the difficulty of isolating the reaction products, and platinum black was more frequently used. On the other hand, the known methods for its preparation were both numerous and uncertain, often yielding a catalyst that was not particularly active.

This state of afiairs persisted until the problem was tackled by Dr. Roger Adams, Professor of Chemistry at the University of Illinois.

Born in Boston in 1889, Adams graduated at Harvard in 1909 and was awarded his Ph.D. three years later, During his college days his love of travel prompted him to work his way to England on a cattle boat, and after receiving his doctorate he again travelled to Europe, this time to study first under Otto Diels at the University of Berlin and then under Richard Willstatter at the Kaiser Wilhelm Institute in Berlin-Dahlem. Few young men can have enjoyed an introduction

to research in organic chemistry under such masters-both to become Nobel Prize Winners in their subject in later years-and their influence upon Adams must have been profound.

In 1913 he returned to Harvard as a member of the teaching staff. Here he stayed for three years, moving in 1916 to the University of Illinois where, apart from intervals of war service, he has remained ever since.

Adams’ great contributions to organic and pharmaceutical chemistry are well known; they covered a wide field and led to many original and valuable discoveries. But we are concerned here only with one of his relatively minor pieces of work-the introduction of the catalyst that has come to bear his name.

During his short period with Willstatter, the latter, working on alkaloids, was engaged among other activities in improving the technique, prescribed in 1890 by Loew, for preparing platinum black by treating an aqueous solution of chlorplatinic acid with formaldehyde, precipitating with alkali, filter- ing off the platinum black, drying in vacuo and exposing to air or oxygen before use as a catalyst. As mentioned earlier, this method did not always yield a satisfactory product. Professor Adams, in response to a request from this journal for details of his own contribution, modestly describes the broad outlines of this phase of his work:

“The story of the discovery of platinum oxide is not spectacular and involved serendipity. When I returned from war service in the spring of 1919, several of the problems I assigned my students involved catalytic reduction. For this purpose we were using as a catalyst platinum black made by the generally accepted best method known at the time, that described by Willstatter and Hatt (Berichte, 1912,45,1471). The students had muchtrouble with the catalyst they obtained in that frequently it proved to be inactive even though prepared by the same detailed procedure which resulted


‘L When I returned from war service in the spring of 1919, several o f the problems I assigned my students involved catalytic reduction. For this purpose we were using as a catalyst platinum black made by the generally accepted best method known at the time. The students had much trouble with the catalyst they obtained in that frequently it proved to be inactive even though prepared by the same detailed procedure which resulted occasionally in an active product. I therefore initiated a research to $nd conditions for preparing this catatyst with uniform activity.”

occasionally in an active product. I therefore initiated a research to find conditions for preparing this catalyst with uniform activity. We had made considerable progress when the paper by Willstatter and Waldschmidt-Leitz (Berichre, 1921,54,112) appeared. In this paper the authors suggested some changes (character of alkali and temperature) in the mode of preparation of the catalyst. They discussed in detail the necessity of oxygen on the catalyst for successful hydrogenation and offered a mechanism.

But even with these modifications of the synthesis, we could not get consistent results and found the method only slightly superior to that previously described by Willstatter and Hatt. Our investigations were therefore continued and yielded good results; they involved more careful definition of conditions and control. We finally reached the point where we were ready for an experiment with a relatively large amount of chlorplatinic acid.

A substantial quantity of spent catalyst was available and we started to convert it into chlorplatinic acid and here is where serendipity came into play. The spent catalyst was con- taminated with a variety of organic materials. Boiling aqua regia dissolved the platinum but the solution remained black from the presence of some unknown substance that was not oxidised. T o remove this it seemed wise to employ oxidation at a higher temperature than that involved with boiling aqua regia, so fusion with solid sodium nitrate was selected for the purpose. Removal of the aqua regia by evapor- ation and then fusion of the residue with sodium nitrate gave voluminous fumes of nitric dioxide and after a bit a brown precipitate appeared which proved to be platinum dioxide. A test of this product as a catalyst resulted in its immediate reduction to a platinum black with potent activity. It required a minimum of time there- after to defme conditions for Preparing a catalyst of satisfactory and uniform (even if not maximum) activity which could be duplicated.”

This account is of course a n over-simplifi- cation of the story. T h e first communication, published in 1922 in the Journal of the American Chemical Society, was in the form of a summarised thesis for the M.Sc. degree in the University of Illinois by one of Adams’ students, V. Voorhees. This paper, with Adams as joint author, set out not only the method of preparation of platinum oxide catalyst, but also the details of the presumed mechanism of its operation. The presence of oxygen in platinum black had already been postulated as necessary to its activity as a catalyst in hydrogenation reactions and Adams and Voorhees concluded that the oxides of platinum, if prepared in a finely divided state, would be as effective catalysts as any that could be prepared, and would be distinctly more active than the best platinum black since the maximum amount of oxygen i n the latter as platinum oxides was o d y around 20 per cent. I t would probably make little difference, they considered, which particular oxide was obtained, since the hydrogen in the reaction would reduce higher oxides to the lower oxide which was presumably the active catalyst. Experiments reported in this first paper included the reduction of phenol and some substituted phenols to hexahydrophenols, of certain


pyridine derivatives to piperidine derivatives, of aromatic and aliphatic aldehydes to the corresponding alcohols, and of heterocyclic compounds to the corresponding saturated derivatives.

There was to follow a considerable number of such papers, most of them with Adams as joint author, from a succession of his students. The second contribution-this time a Ph.D. thesis-came less than a year later from the late Wallace Hume Carothers, who will be so well remembered for his subsequent work as leader of the Du Pont team assembled to search for a synthetic fibre-the search concluding so brilliantly in the development of nylon. Other student co-authors over the next two to three years included R. L. Shriner, W. E. Kaufmann, J. S. Pierce, J. W. Kern, €3. Heckel, W. F. Tuley and B. S . Garvey. Many variables in the details of preparing platinum oxide catalyst were explored, and many reductions investigated, much of the work being summarised in 1928 in Volume VIII of “Organic Syntheses”, the annual publication on methods for the preparation of organic chemicals founded and edited by Adams. The detailed procedure set out here provided only for a very small scale preparation yielding a few grams of catalyst. If a greater quantity was required, the reader was advised to make several runs of the size indicated rather than one large run since spattering and the evolution of gases made large amounts inconvenient to handle. In the earlier days of its usefulness, Adams’

catalyst was prepared by the individual research worker on this modest scale, but before long its use became more extensive and in the late thirties the demand began to reach an industrial scale. The repeated preparation of very small quantities then became quite impracticable, and the problem of scaling-up was tackled by the leading platinum manufacturers in the United States and Europe. In England, Johnson Matthey collaborated with May & Baker Limited, whose needs of Adams’ catalyst for a variety of hydrogenation reactions ran at that time

into several hundred grams, and a process was worked out, still based essentially on Adams’ procedure, but modified in several details to enable much larger batches to be prepared. Ammonium chlorplatinate was substituted for chlorplatinic acid, the sodium nitrate was first fused alone, and the final melt was poured directly into water so that the excess sodium nitrate and other salts dissolved immediately, leaving the platinum oxide behind, so avoiding the tedious digestion of the melt and reducing the time required for preparation. This method has since been the subject of further modifications in terms of the temperatures employed and of the ratio of sodium nitrate to ammonium chlorplatinate, but basically it still serves as one reliable means of production, and large quantities of Adams’ catalyst have been prepared in this way over the years.

As recently as 1960 an interesting development of Adams’ original work was put for- ward by Dr. Shigeo Nishimura, of the Uni- versity of Tokyo. Realising that rhodium behaved as a specially effective catalyst for the hydrogenation of the aromatic nucleus, but that most of the published work in this field had been concerned either with colloidal rhodium or with a supported - rhodium catalyst, Nishimura set out to prepare an Adams-type catalyst consisting of rhodium oxide and platinum oxide in a ratio of three to one by weight of the metals. By fusion of a mixture of rhodium chloride and chlorplatinic acid or ammonium chlorplatinate with sodium nitrate in exactly the same manner laid down by Adams, he obtained a mixed oxide catalyst-not identical with a simple mixture of the two oxides-which he claimed to be superior to Adams’ platinum oxide in a number of hydrogenations.

Many other types of hydrogenation catalyst have of course been developed during the past forty years, and a great-if incomplete- wealth of understanding of their behaviour has been built up. None the less Adam’ original catalyst still finds extensive use in liquid phase work. L. €3. H.


ABSTRACTS of current literature on the platinum metals and their alloys

PROPERTIES An Investigation of the Palladium-Gold- Nickel Alloy System

KUPRINA, G. v, GOLDOBINA and M. A. RUDNITSKII, Zhur. Neorg. Khim., 1962, 7, (5), 1110-1116

Alloys with Pd content fixed at 10,20,30,40, 50, 60, 70, 80, or 90 wt.% and variable amounts of Au and Ni were studied by thermal analysis and determination of hardness, microstructure, specific electrical resistance and its temperature coefficient. It was shown that a continuous series of solid solutions is formed immediately after solidification. Alloys with up to 20 wt.% Pd undergo decomposition in the solid state with the formation of a wide region of mechanical mixtures. Curves showing the relationship between composition and physical properties are given.

The Constitution Diagram of the Osmium- Ruthenium Alloy System M. A. TYLKINA, v. P. POLYAKOVA and E. M. SAVITSIUI, Zhur. Neorg. Khim., 1962, 7, (6), 1467-1468 The diagram was constructed by methods of physico-chemical analysis. Alloy samples in both the cast and annealed state were examined. A continuous series of solid solutions with melting temperatures between those of 0 s (305o"C) and Ru (z250'C) was found. Cast alloys at all compositions showed a dendritic structure. The hardness is variable with a maximum in the composition range 60-70 wt."/, 0s .

The Constitution Diagram of the Osmium- Rhenium System M. A. TYLKINA, v. P. POLYAKOVA and E. M. SAVITSKII, Zhw. Neorg. Khim., 1962,7, (6), 1469-1470 Physico-chemical methods were used to examine alloys of the system. An uninterrupted series of solid solutions with melting temperatures between those of 0 s (305o'C) and Re (3170°C) was found. Maximum hardness for alloys in the cast and annealed states is obtained in the composition range 6 0 7 0 at.% 0s.

An Investigation of Alloys of Bismuth with Platinum in the Range 10 to 50 At.:/o Platinum

SMIRNOVA, Fiz. Metallov i Metallotled., 1962, 13, (41,536345 The portion of the Pt-Bi phase diagram which lies between the compounds PtBi and PtBia was

A. T. GRIGOR'EV, L. A. PANTELEIMONOV, V. V.

N. N. ZHURAVLEV, G. S. ZHDANOV and E. M.

determined precisely by thermal analysis and X-ray and metallographic phase analysis. A y-phase ( ? Pt,Bi,) formed by a peritectic reaction exists between PtBi and PtBiz and undergoes eutectoid decomposition into PtBi and PtBi,. Superconductivity of the alloys was studied.

The Constitution Diagram of the Palladium- Iridium System

Zhur. Neorg. Khim., 1962, 7 , (6), 1471-1473 The system was investigated by thermal analysis, microstructural and X-ray phase analysis, and by hardness measurements. A peritectic-type diagram with two limited solid solutions (a-solid solution of Ir in Pd and P-solid solution of Pd in Ir) was constructed. A two-phase (ci + (3) region exists between the a- and P-solid solutions. No chemical compounds were detected in the system. Hard- ness measurements confirmed the microstructural and thermal analysis of the system.

Borides of Ruthenium, Osmium and Iridium B. ARONSSON, E. STENBERG and J. ASELIUS, Nature, 1962, 195, (Jul. 281,378-379 Crystallographic constants are given for the phases

O S B ~ . ~ , OSB-~.~, O S B - ~ . ~ , 1rBmlal, and IrB-l.I.

Conductivity and Hall Constant. XXIII. The Temperature Dependence of Resistance and Hall Constant of Palladium Alloys w. GMOHLING and D. HAGILIA", Z. Metallkunde, 1962, 53, (71,459-465 Measurements of the temperature coefficient of resistivity and Hall coefficient at room temperature were made on alloys of Pd with up to 4 at.% Ag, Cd, In, Rh, Ru, Mo, Nb, Zr, or V. It was found that the absolute temperature coefficient of resistivity is decreased by all alloying additions. An even more marked decrease in the absolute temperature coefficient of the Hall constant occurs on addition of the alloying metals. These changes are related to changes in the electronic structure of the Pd.

Thermodynamics of Ordering Alloys. IV. Heats of Formation of Some Alloys of Transition Metals R. ORIANI and w. K. MURPHY, Acta Met., 1 9 6 2 , 10,

(91,879-885 The heats of formation of Ag-Pd, Cu-Pd, Cu-Pt and Co-Pt alloys were measured at 642" , 6 4 2 " ,

M. A. TYLKINA, V. P. POLYAKOVA and E. M. SAVITSKII,

RuTB, RuiIB,, R~Bwi.1, RUBw1.6, RuB~2.1 ,


640"~ and 641'C, respectively, and at temperatures in the range 50O0-74Ooc for the alloy Cu,.,Pd,. 4. Large negative enthalpies of formation were found for these alloys and large negative excess entropies of formation were calculated.

Electrical Resistivity Recovery in Cold- worked 60% Silver-400/, Palladium Alloy K. K. RAO, Acta Met., 1962, 10, (9), 900 Decreases in resistivity of the plastically deformed alloy were observed between So-120°C and between z40-300°C. The specimen was held at various temperatures in these ranges for 30 min. periods.

A Contribution on the Structure of the Palladium-Ruthenium System and on the Properties of Palladium-Rich Alloys w. OBROWSKI and G. ZWINGMANN, Z. Metallkunde,

The structure of alloys containing up to 40 at.?; Ru was investigated by thermal, X-ray and microscopic methods. Measurements of hardness, specific electrical resistance and its temperature coefficient, thermoelectric properties and lattice constants were made and corrosion properties were observed. No evidence of a stable inter- metallic phase was found. The possibility of age- hardening alloys with 6 to 10 at.% Ru was shown. Corrosion properties were found to be similar to those of pure Pd. Internal oxidation occurs on heating the alloys in an oxygen-containing atmosphere.

Stability of Solid Phases in the Ternary Systems of Silicon and Carbon with Rhenium and the Six Platinum Metals A. W. SEARCY and L. N. FINNIE, J. Amer. Ceram. Soc., 1962~45, (6), 268-273 Phase studies were carried out at 1600°C for Re-Si-C, 1340°C for Ru-Si-C and Ir-Si-C, 1350°C for 0s-Si-C, and 1170°C for Rh-Si-C. The only stable phases at these temperatures are solid metal silicides and Sic. The Pt-Si-C and Pd-Si-C systems were examined during cooling from above the liquidus temperatures. The thermodynamic stabilities of the metal silicides was studied, and heats of formation for the Pt metal silicides were estimated.

An Anomaly in the Electrical Resistance and Formation of the K-State in the Palladium- Tungsten and Palladium-Molybdenum Systems v. s. MES'KIN, R. I. SERGIENKO and L. A. POPOVA, Fiz. Metallov i Metalloved., 1962,13, (I), 126-131 Pd alloys containing 13-20 wt.0,; W and 5.5-100,; Mo show anomalous electrical resistance on annealing. The production of the K-state in these alloys is indicated. Variations in the electrical properties of these alloys on the formation of the K-state were investigated.

1962J 53, (7)J 543-455

Activities of Iron in Iron-Platinum Alloys at 1300°C R. w. TAYLOR and A. MUAN, Trans. Met. soc.

Mixtures of Pt metal and Fe,O, were equilibrated at 13ooOC and at known oxygen pressures. Com- positions of Fe-Pt alloy phases at equilibrium were determined by measurement of weight changes of the mixtures and are shown graphically with those of the Fe oxide phase. A negative deviation from Raoult's law is shown by the activity of Fe in Fe-Pt alloys.

The Electrical Resistivities of the Palladium- Silver Alloys B. R. COLES and J. c. TAYLOR, Proc. Roy. SOC., Series A, 1962, 267, (1328), 139-145 Resistance measurements were made on wire specimens of alloys of the system and resistivities were calculated as a function of temperature and composition. Residual resistivity and temperature-dependent resistivity were calculated using the theoretical model of Mott and the observed values for the density of electron states at the Fermi surface. With the exception of the temperature-dependent resistivity near pure Pd, good agreement was obtained between experimental and theoretical results.

Alloys of the First Transition Series with Palladium and Platinum S. J. PICKART and R. NATHANS, J . Appl. Phys.,

Neutron diffraction measurements were used to determine the magnetic moments on the constituent atoms of the ordered alloys FePd,, MnPtB, and Cr,.,Pt,.,. The results for FePd, are consistent with those obtained by other workers from magnetisation measurements. At room temperature the magnetic ordering in Cr,.,Pt,., is ferrimagnetic.

Neutron Diffraction Investigations of Ferro- magnetic Palladium and Iron Group Alloys

M. K. WILKINSON,J. Appl. Phys., suppl. to 1962,

The individual magnetic moments of the constituent atoms of the ferromagnetic alloys Pd,Fe, PdFe, Pd,Co, PdCo, Ni,Co, and NiCo were determined by the combination of neutron diffraction and magnetic induction measurements. Results are given in a table.

Anomalous Magnetic Moments and Trans- formations in the Ordered Alloy FeRh J. S. KOUVEL and C. C. HARTELIUS, J. Appl. Phys.,

Magnetisation and electrical resistivity measurements were made on an Fe-Rh alloy containing 52 at.% Rh. A first-order antiferromagnetic- ferromagnetic transition at about 350°K indicated

A.Z.M.E., 1962, 224, (3), 500-502

S ~ P P ~ . to 1962,331 (31, 1336-1338

J. W. CABLE, E. 0. WOLLAN, W. C. KOEHLER and

33, (3)J I34O

SUPPI. to 1962, 33, (31, 1343-1344


by earlier X-ray and neutron diffraction investigations was confirmed. The alloy has a ferromagnetic Curie temperature of 675°K.

Platinum Group Metals and Rhenium A. V. FRANCIS, Me'tallurgie, 1962, 94, (3), 233-245 The chemical, physical, and mechanical properties of the Pt metals and their alloys are described. Industrial applications of the Pt metals are discussed. The production of Re and its applications, together with those of its alloys with Mo and Ir, are outlined.

Contact Potential in Thin MetaI Films S. M. BRYLA and C. FELDMAN,J. A@. Phys., 1962, 33, (31, 774-776 Contact potential difference between a Pt reference surface and films of Au, Pt, and Ag was measured in an attempt to find a work function variation with film thickness. The films were vacuum deposited on to fused SiO, sub- strates. In the range of 5 ohms,kq. to IO* ohms/ sq. the contact potential was found to be independent of film resistance or thickness.

Temperature Coefficient of Electrical Resis- tance of High-Purity Rhodium E. G. PRICE and B. TAYLOR, Nature, 1962, 195,

Resistivity measurements were made on commercial grade and specially purified Rh wire. The temperature coefficient of electrical resistance beteen oc and 100°C for the commercial grade Rh was found to be 0.00461 and that for purified Rh was 0.00463. Mass-spectrographic analyses of both samples are given.

J . c. CHASTON, Nature, 1962, 195, (Aug. zS), 793 Measurements made in 1936 on specially purified Rh gave a value of 0.00463 for the temperature coefficient of electrical resistance.

(Jul. zI), 272-273

Structure of Hydrides of Palladium J. G. ASTON and P. MITACEK, Nature, 1962, 195,

Heat capacities of PdH, for x = 0.5 and x = 0.75 were determined, and it is shown that between 35°K and 85°K the heat capacity is independent of hydrogen concentration up to 0.75 HlPd ratio. Structures are proposed for the (3-phase and @-phase hydrides. Ring diffusion and long- range diffusion processes cause the warm drifts observed between 150°K and zooOK and between ZOO'K and 250CK, respectively.

The Vapour Pressure of Palladium R. P. HAhWSON and R. F . WALKER,.y. Res. Nut. Bur. Stds., Sectioiz A, 1962, 66A, ( z ) , 177-178 A vacuum microbalance technique was used in the measurement of vapour pressure and heat of sublimation. Over the temperature range 1294' to 1488°K the measured vapour pressures may be

(Jul. 71, 70-71

represented by log Pmm = 8.749 - 186551T. The mean heat of sublimation obtained was 89.2+0.2 kcal/mole. The normal boiling point is estimated to he 3200-K.

Electrochemical Determination of the Heat of Adsorption of Hydrogen on Finely Divided Palladium ZH. L. VERT, I. A. MOSEVICH and I. R. TVERDOVSKII, Proc. Acad. Sci. U.S.S.R., Phys. Chem. Section, 1961, 140, (I+ 662-664 (Transl. of DokZady Akad. Nauk S.S.S.R., 1961, 140, (I), 149-152) I t was shown by the study of charge curves that in the presence of SO4*- ions the heats of adsorption, Q, remain constant at 27.5 kcal/mole in the range o<O<0.5 (0 = fraction of surface covered by hydrogen). As 0 increases above 0.5, Q decreases. The heat of adsorption of hydrogen found in HCl solutions is lower than the value found in H,S04 solutions. The heats of adsorption on several Pd-Ag alloys were determined in IN H,SO,.

Electrical Resistance of Alpha Hydrogen- Palladium w. T. LINDSAY and F. w. PEMENT, J. Chem. Phys.,

Resistance measurements were made on gas- charged ctH-Pd wires, 0.1 mm in diameter, in the temperature range 100-400°C. It was found that the small increase of Pd resistance on adding hydrogen is proportional to hydrogen concentration and that the constant of proportionality is independent of temperature. In the range 75-400°C and for a-phase compositions up to 0.1 m, the observed data may be expressed by the equation: (Rpd/Rpd')-I =(2.41 k0.04) m, where R =resistance of aH-Pd, R" =resistance of hydrogen-free Pd, and m=H:Pd atom ratio.

Interaction of Helium, Neon, Argon, and Krypton with a Clean Platinum Surface H. CHON, R. A. FISHER, R. D. MCCAMMON and J. G . AS TON,^. Chem. Phys., 1962, 36, (5), 1378-1382 Heats of adsorption of He, Ne, Ar, and Kr on Pt were measured and the values obtained were compared with those calculated theoretically for the attractive part of interaction energy between a nonpolar gas and a metal surface.

Study of the Adsorption of Hydrogen, Ethane, Ethylene, and Acetylene on Iridium by Field Emission Microscopy 1. R. ARTHUR and R. S. HANSENS J . Chem. Phys., 1962,36, (S), 2062-2071 Changes in emission patterns and work functions resulting from time- and temperature-dependent surface reactions were studied. In the temperature range 7O0-30O0K a rather uniform covering of the high index faces of I r was indicated. Surfaces containing adsorbed species were flashed to various temperatures for various periods of time.

1962,36, (519 1229-1234


Results showed that hydrogen, C,H,, and C,H, are chemisorbed by Ir below 77"K, and C,H, is largely physically adsorbed. Hydrogen is desorbed over the temperature range 200~-400~K, adsorbed C,H4 decomposes at about 200°K to CzHs and hydrogen (both of which are then adsorbed), and adsorbed C,H, dehydrogenates over the temperature range 400°-6000K.

Palladium and Palladium Alloys for the Preparation of High-purity Hydrogen G. F. P. M ~ ~ L L E R , Z. Metallkunde, 1962, 53, (7), 449-453 Hydrogen diffusion and solubility in Pd, 207, Au-Pd and 30:; Au-Pd were measured. The dependence on temperature of the hydrogen diffusion and the electrical resistance of Pd was investigated during thermal cycling. Changes in the mechanical properties of Pd and Ag-Pd on heating in hydrogen were also studied and correlated with the structure of the PdH formed. The construction of diffusion cells for the purification of hydrogen and for its separation from other gases is discussed.

ELECTROCHEMISTRY Anodic Oxidation of Methanol on Platinum. I. Adsorption of Methanol, Oxygen, and Hydrogen on Platinum in Acidic Solution M. w. BREITER and s. GILMAN,~. Electrochem. SOC.,

Potentiostatic and galvanostatic techniques were used to determine the coverage of bright Pt electrodes with CH,OH, hydrogen, and oxygen in IN HClO, containing different amounts of CH,OH. CHsOH coverage is independent of potential between $0.1 and $0.6 V and decreases rapidly with potential above +0.6 V during the anodic sweep of the current-potential curve. Saturation coverage of CH,OH present on the surface decreases hydrogen adsorption by 75%. Oxygen coverage in IN HC10, and I N HClO,+rM CH,OH is nearly the same.

The Utilisation of the Palladium-Hydrogen Electrode H. SHIRATORI, J. Electrochem. soc. Japan, 1961, 29, (31, E-161 A Pd-H alloy in which cc- and @-phases coexist may be used in the measurement of the pH of a solution and as a reference electrode in potential measurement.

1962, 109, (71,622427

ELECTRODEPOSITION Industrial Applications of Noble Metal Plating G. BACQUIAS, Mkallurgie, 1962, 94, (6), 623-626 The properties of electrodeposited Ag, Au, Rh, Pd, and Pt are compared and criteria by which

suitable coatings may be selected are given. Modern methods for obtaining homogeneous deposits are discussed. Applications in the electrical and electronic industries are mentioned.

METAL WORKING Brazing for Elevated Temperature Service D. w. RHYS and w. BETTEFUDGE, Metal Industry,

Various brazing methods and the design of joints are described. Brazing conditions and require- ments for many individual basis materials and the suitability of particular brazing alloys are discussed. The properties of the most common brazing alloys are described and the applications of brazed joints using these materials are considered. Pd-containing brazing alloys are recommended for many high-temperature applications.

1962, 101, (I), 2-4; (21, 27-30; (3)145-46

CATALYSIS Competitive Catalytic Hydrogenation of Benzene, Toluene and the Polymethyl- benzenes on Platinum c. P. RADER and H. A. SMITH,^. Amer. Chem. soc.,

Adams' (PtO,) catalyst was used in the hydrogenation reactions which were carried out at 30°C in the hydrogen pressure range 35-60 p.s.i. The relative ease of adsorption of the hydrocarbons on the active catalyst surface does not necessarily correspond to the relative reduction rates of the individual hydrocarbons. With the exception of C,(CH,),, ease of adsorption decreases with increasing nuclear substitution and for a given set of polymethylbenzene isomers, decreases with increasing symmetry of substitution. The mechanism of the reduction process is discussed.

New, Highly Active Metal Catalysts for the Hydrolysis of Borohydride H. c. BROWN and c. A. BROWN,?. Anzer. Chem. soc.,

The catalytic effect of Ru, Rh, Pd, Os, Ir, and Pt on the hydrolysis of a solution of NaBH, was investigated. 5 ml of a 0.100 M solution of the Pt metal salt was injected into a stirred solution of 1 g NaBH, in 45 ml H,O at 25'C. The Pt metal salts were reduced to the corresponding pure metal powder and hydrogen was evolved. Catalytic activity observed was in the order: Ru, Rh>Pt > 0 s > Ir > Pd.

A Simple Preparation of Highly Active Platinum Metal Catalysts for Catalytic Hydrogenation Ibid., 1494-1495 Finely-divided Pt metal catalysts produced in situ by NaBH, reduction were used in the hydrogenation of I-octene. With Pt as catalyst,

1962, 84, (81, 1443-1449

1962,84, (8), 1493-1494


absorption of hydrogen was complete in 16 to 18 min. On a weight basis, Rh is approximately twice as effective as the Pt catalyst and almost four times as effective as commercial PtO, catalyst in this hydrogenation reaction. Ru, Pd, Os, and Ir are less effective than commercial PtO,.

A New Convenient Technique for the Hydrogenation of Unsaturated Compounds Ibid., 1495 A Pt catalyst formed in situ by NaBH, reduction of H,PtCI, and hydrogen generated in situ by the hydrolysis of NaBH4 were used in the laboratory- scale hydrogenation of unsaturated compounds. I-Octene, 2-octene, 2, 4, 4-trimethyl-1-pentene, cyclohexene, cyclooctene, norbornene, +vinyl- cyclohexene and 3-hexyne underwent quite rapid hydrogenation. The reaction time for I-octene is 9-10 min.

Stereochemistry and Mechanism of Silane Additions to Olefins. 11. Chloroplatinic Acid-Catalysed Addition of Trichlorosilane to Alkylcyclohexenes T. G. SELIN and R. WEST, J. Amer. Chem. SOL., 1962, 84, (IO), 1863-1868 Addition of HSiCI, to 4-methylcyclohexene, I-methylcyclohexene and I-ethylcyclohexene in the presence of H,PtCl, resulted in terminal adducts. With 4,4-dimethylcyclohexene, addition to the ring was observed. Addition to +methylcyclohexene is preceded by isomerisation to I-methylcyclohexene. HSiCI, does not add to I-n-propylcyclohexene and I-n-octylcyclohexene. Mechanisms for the addition reactions are discussed and it is suggested that the addition occurs through a specific olefin-catalyst or olefin- catalyst-silane intermediate.

Differences in the Catalytic Activity of Nickel, Platinum and Palladium as Observed in the Isotopic Exchange Reaction of Paraxylene with Deuterium Oxide K. HIROTA and T. UEDA, Bull. Chem. soc. Japan, 1962, 35, (2), 228-232 This investigation confirmed that with a Ni catalyst only hydrogen atoms of methyl groups of paraxylene exchange with D,O. With Pt black and Pd black catalysts and under similar experimental conditions, hydrogen atoms of both methyl groups and the benzene ring exchange with D,O. Ni/A1,0, has a similar catalytic activity to Pt black and Pd black in this exchange reaction, but with Ni lSi0 and Nilkieselguhr there is no exchange of hydrogen in the benzene ring.

Cold Hydrogenation of C,-Fractions in the Liquid Phase w. ~ G N I G , Erdol u.Kohle, 1962, 15, (3)J 176-179 The liquid phase selective hydrogenation of the

C,-fraction in order to remove contaminants from CsHo may be carried out in the temperature range 10' to 20°C with the use of a Pd/A1,0, catalyst. The successful operation of this process in the trickle phase on a commercial scale is described. Other applications of cold hydrogenation in refining processes not restricted to C,-fractions are described.

A New Branch of Petrochemistry - The Technique of Producing Aromatics from Petroleum G. VOSS, Erdol u.Kohle, 1962, 15, (9, 387-391 The development is described of the petro- chemical industry of West Germany and the U.S.A., with particular reference to the production of aromatic hydrocarbons. Modern methods of producing aromatics from petroleum are described and illustrated by flow diagrams. The use of Pt/AI,O, catalysts in the Platforming and Octafining processes is mentioned.

Catalysts and Chemicals in Refining Opera- tions J. A. E. MOY, Petroleum, 1962, 25, (5), 150-155 The use of Pt and base metal catalysts in many processes currently employed in petroleum refining is described. Types of operation discussed include reforming, isomerisation, cracking, hydrocracking, hydrotreating, and treatment by chemicals. (60 references)

Paraffin Isomerisation with Hydrogen Chloride-Promoted Dual Function Catalysts 0. H. THOMAS, J. MOOI, R. s. BARTLETT and R. A. SANFORD, Ind. Eng. Chem, (Process Design & Development), 1962, I, (z), 116-120 The hydro-isomerisation of n-C,H,,, n-C,H12, and n-C,H14 was investigated in the temperature range 550"-75o"F using Pt/Al,O,, Pt/B,O,/ A1,0,, Pd/Al,O,, Pd/Bz03/A1,03, Pt/SiO,, and Pt /C catalysts with HC1 as a promoter. In contrast to the Al,O,-supported catalysts, Pt / S O , and Pt/C are not activated by HCI. Decom- position of the Al,O, support by HC1 attack is prevented by the incorporation of B,O,, and catalyst activity and selectivity is maintained. Aromatic and naphthenic components present in the feed do not alter catalyst performance. The performance of a 0.67& Pt/Io% B,O,/Al,O, catalyst is reported in detail.

Hydrogenation of Linolenate. VI. Survey of Commercial Catalysts A. E. JOHNSTON, D. MACMILLAN, H. J. DUTTON and J. c. COWAN, J. Amer. Oil Chem. Soc., 1962, 39, (619 273-276 PtO,, 5:4, Pt/C, 574, Pt/Al,O,, 5% Pd/CJ 5% Pd/AlzOs, and various supported Ni catalysts were used in this search for catalysts with high seleaivity and low isomerising properties. The ratio of hydrogenation rates for lindenate to


linoleate was determined on an equal mixture of methyl linolenate and linoleate and the percentage of trans esters formed was determined. Hydrogenation was carried out at room temperature with Pt and Pd catalysts and at 140°C with Ni catalysts. Pt catalysts produced lowest isomerisation, but their selectivities were lower than those of the Ni and Pd catalysts.

Catalysis in a Modern Petroleum Refinery c. L. THOMAS, Chim. t3 Ind., 1962, 87, (4,496-506 The processes of catalytic reforming, catalytic cracking, propylene polymerisation, alkylation, and desulphurisation are outlined and the functions of the catalysts used in them are discussed.

The Hydrogenation of Fatty Oils with Palladium Catalysts. VI. Hydrogenation for Margarine M. ZAJCEW, J . Amer. Oil Chem. Soc., 1962, 39, (6), 301-304 Margarine stocks were produced by the hydrogenation of various oils in the presence of I”< PdjC or 5% Pd/C catalysts. Processing was carried out on laboratory, pilot plant, and plant scales. It is possible to produce margarines of difFerent compositions and trans isomer content by varying the catalyst and the processing conditions. Tables give details of these conditions and analyses of the products.

Flow Adsorption Method for Catalyst Metal Surface Measurements T. R. HUGHES, R. J. HOUSTON and R. P. SIEG, Id. Eng. Ckem. (Process Design and Development), 1962, I, (2), 96-102 In this method, which involves the measurement of chemisorption of CO, CO mixed with un- adsorbed helium as a carrier is passed over the prereduced catalyst. The concentration of CO in the effluent gas is measured by a radioactive tracer method. Applications in the study of Pt reforming catalysts and of RhiAl,O,, Ni/Al,O,, Cr,O,/Al,O, are described. The method was used to study the effect of Pt content and support surface on CO chemisorption and Pt particle size, the relationship between metal surface and catalytic activity, and sintering effects.

Development of a Catalyst for the E h i n a - tion of Acetylene from an Ethane-Ethylene Fraction by Means of Selective Hydrogen- ation H. BLUIME, J. M m Z I N G and H. STURTZ, chem. Techn., 1962, 14, (4), 214-221

Experimental work leading to the production of a Pd/Al,O, catalyst suitable for the gas-phase hydrogenation of the C,-fraction is described. Properties of the catalyst (VEB Leuna-Werke “Walter Ulhricht” 7746) are given in detail and its performance is compared with that of similar catalysts developed in the U.S.A. (26 references)

Reaction of Ethane with a Clean Rhodium Film R. w. ROBERTS, Trans. Fai-aday SOC., 1962,58, (6),

Rh films of thickness 10 to 18oA were prepared by evaporating a small coil of 0.005 in. diam. pure Rh wire in the centre of a Pyrex reaction vessel under high vacuum conditions. Experiments showed that C,H, decomposes on such films at temperatures as low as 0°C to give CR, and a hydrocarbon residue adsorbed on the film. The activation energy for the disappearance of C,H, is 15 5 I kcal/mole. Oxygen adsorbed on a clean Rh film inhibits the cracking of CzH,. The mechanism of the cracking reaction is discussed.

Variation of Catalytic Properties in the De- composition of Formic Acid on Platinum and the Effect of Adsorbed Gases

1159-1169

L. RIEKERT, z. E1ektrochem., 1962,66, (3)~ 207-222 Experiments with electrically-heated Pt wires showed that if the contact temperature is kept below 600‘C, the catalytic activity of the Pt decreases during the reaction. The initial activity and its rate of decrease depend on the previous history of the catalyst. Kinetic results obtained are explained by the assumption that the irreversible adsorption of oxygen or hydrogen affects the rates of the various transformations of the substrate occurring simultaneously on the Pt surface.

Pyrimidines VI. Reduction of Certain Pyrimidines

A Study of the Nuclear

H. AFT and B. E. CHRISTEN SEN,.^. &g. Chem., 1962, 27, (61, 2170-2173 Adams’ (PtO,), PdlBaSO,, and roo,’, Pd/C catalysts were used in the nuclear reduction of chloro-, amino-, and methylpyrimidines and their chloro derivatives in acid media. It was found that hydrogenation ceases after consumption of sufficient hydrogen for the conversion to the corresponding 3, 4, 5, 6-tetrahydro-pyrimidine. The tetrahydropyrimidines may be isolated as the picrate derivatives in low yields. The nuclear reduction products are unstable in aqueous media.

The Activation of Platinum Catalysts by Rare Earth and Other Oxides in the De- composition of Hydrogen Peroxide E. B. MAXTED and S. M. ISMAIL,y. Chem. soc., 1962, (Jun.), 2330-2333 The activity in the decomposition of aqueous H,O, of a constant amount of Pt supported on various metallic oxides was measured at 20°C and I atm. With each support, the activity of the catalyst reached a maximum and then decreased on increasing the amount of oxide. The activities of the oxide promoters investigated was in the order: ThOz>ZrO, > Cr,O,>CeO,>MgO> Ti0,>V,0,>La,03>Pr,0,,>T1,0,> Sm,O,. In many cases the activity of the supported Pt


was considerably greater than that of unsup- ported Pt. Activation by two-component and three-component oxide support systems was also studied.

Rhodium Catalysed Nuclear Hydrogenation of cc-Substituted Benzyl Alcohols and Ethers. A Useful Procedure for Establishing Configurations J. H. STOCKER, J . Org. Chem., 1962, 27, (6), 2288-2289 Hydrogenation of several or-substituted benzyl alcohols and ethers was achieved at room temperature and a hydrogen pressure of 3-4 atm with the use of a 5:; Rh/AIz0, catalyst.

The Detoxication of Palladium Catalysts Poisoned hy Various Metallic Ions E. R. MAXTED and s. I. A L I , ~ . Chem. soc., 1962,

The reactivation of Pd and Pd/ThO, catalysts poisoned by Zn-, Cd-, Pb-, Hg-, and As-containing ions adsorbed on their surface was studied. The activity of treated catalysts was compared with that of unpoisoned catalysts for the hydrogenation of cyclohexene in C,H,OH at 20°C. Methods of treatment included (i) washing with H,O, CH,CO,C,H,, dilute CH,COOH, and C,H,OH, (ii) treatment with cyclohexene, and (iii) treatment with diethyl sulphide.

Selective Poisoning of the Catalyst in the Rosenmiind Reaction S . AFFROSSMAN and S. J. THOMSON,J. Chem. soc., 1962, (May), 2024-zo29 The effect of sulphur-containing poisons on yields of C6H6CH0 produced by the hydrogenation in C,H,CH, of C,H5COCl over a Pd/BaSO, catalyst was studied at 110°C and I atm. There is no apparent correlation between the size of a poison molecule and its effectiveness in preventing hydrogenation beyond the aldehyde stage. Of the poisons studied, tetramethylthiourea was the most effective. I t is concluded that the Rosenmund reaction is a consecutive hydrogenation, and a selective-poisoning mechanism is proposed.

The Catalytic Isomerisation of Alkanes

Tech. , 1962, 14, (5/6), 375 (Abstract of paper presented at the Petroleum Conference, Budapest, April 1962) The properties of six Pd/Re/Al,O, catalysts were investigated. In the isomerisation of C,H,, under optimum conditions the catalyst performance varied according to the method of preparation. Up to 5zyu iso-C6H14 was produced in the presence of 1% Pd/Al20, or I ~ L Pd/zO,, Re/ A1,0, catalysts treated with H,S. The addition of 106 Re to PdiAl,O, treated with H,S increases its stability. 48;; isomerisation of C5HI2 was achieved with the Pd/Re;Al,O, catalyst.

(Jul.), 2796-2801

M. A. RASCHENZEWA and H. M. MINATSCHEW, Chem.

Cyclohexane H. W. HAINES, Ind. Erig. Cham., 1962,54, (7), 23-30 The production and industrial uses of cyclohexane are discussed. Commercial processes for the hydrogenation of C,H, to cyclohexane which are described include the U.O.P. process in which a Pt catalyst is employed.

Catalytic Hydrogenation of Nitrosamines to Unsymmetrical Hydra~ines G. w. SMITH and D. N. THATCHER, Ind. Eng. Chem. (Product Res. & Dev.), 1962, I, (2), 117-120 An inorganic or organic salt was added to the reaction mixture in the hydrogenation of various nitrosamines in the presence of 107; Pd/C, 10% PtK, and 5% RhiC. In all cases, salt addition suppressed conversion to the corresponding amine, but the effect was less marked with RhjC catalysts. The salts used included LiCl, CaCl,, LaCl,. 7H@, (CH,),NBr and MgSO,, and the solvents were H,O or H,O/alcohol. The effects of temperature and pressure on the course of the reaction were studied. The hydrogenation mechanism is discussed.

Spectrophotometry and Light Scattering on Supported Platinum P. DEBYE and B. CHU, J . phys. Chem., 1962, 66, (6), 1021-1027

An immersion technique was used to measure transmission and scattering for visible light of dispersed Pt on an A1,0, support. The nature of the dispersed Pt was deduced from the extinction coefficient and the increase in the refractive index of the Alz03 due to dispersion of Pt at its surface. I t was assumed that part of the Pt was in an “atomic” state.

Interaction of Hydrocarbons with Platinum/ Alumina in the Presence of Hydrogen and Helium J. C. ROHRER and J. H. SIN FELT,^. Phys. Chem.,

The activity of 0.394 Pt/Al,O, catalyst for the dehydrogenation of methylcyclohexane to C,H,CH, and the dehydrocyclisation of n-C,H,, to C,H,CH, was determined in the presence of hydrogen and helium carrier gases. In both cases, the initial catalytic activity was lower in the presence of helium than in hydrogen. Cata- lytic activity was largely regained on changing the carrier gas from helium to hydrogen. The role of hydrogen in maintaining the activity of the catalyst surface is discussed.

The Catalytic Exchange with Deutcriuni of Polymethylcyclopcntanes on Metal Films. Evidence for a-Bonded Intermediates

Catalysis, 1962, I, (31, 255-274 The catalytic exchange reaction on films of Rh, pd, pt, and Ni was studied by a mass-spectro-

1962,662 (6), 1193-1194

F. G. GAULT, J. J. ROONEY and C. KEMBALL, J .


metric technique, and cis-trans isomerisation was investigated by gas-liquid chromatographic analysis of the reaction products. A new mechanistic theory involving the formation of x-bonded as well as a-bonded intermediates is supported by experimental results. n-bonding is most evident with Pd films. Although Rh is the most active of the metals for the exchange reactions, 0-

bonded intermediates predominate at lower temperatures. As with both Pt and Ni films, x-bonding increases with rise of temperature. (27 references)

ELECTRICAL ENGINEERING The Conductivity of Oxide Cathodes Part 12. Influence of Strontium Ion Migra- tion on Matrix Conductivity G. n. METSON, R o c . Instn. Elect. Engrs., Part C,

The migration of Sr was studied in an S-type assembly having pure Pt cores and a Ba-Sr oxide matrix. It was shown that positive Sr ions migrate in an electric field to the Pt cathode core, forming a Sr-Pt alloy. The positive ions are mobile in a low electric field at 550°K and are unable to diffuse in a concentration gradient below 800°K. Excessive concentration of Sr ions results in an increase in matrix resistivity.

1962, 109, (IS), 138-145

TEMPERATURE MEASUREMENT Reference Tables for 40 Per Cent Iridium- 60 Per Cent Rhodium Versus Iridium Thermocouples

Bur. Stds., Purr C, 1962, 66C, (I), 1-12

The method of calibrating Ir : 40% Ir-Rh thermocouples is described in detail. Temperatures up to 2500°F were measured in a Pt-wound furnace by a Pt : lo:,:, Rh-Pt thermocouple. In the temperature range 1950°-3800"F, calibration was carried out in an induction furnace which contained an I r cylinder blackbody, and an

G . F. BLACKBURN and F. R. CALDWELL,J. Res. Nut.

NEW PATENTS Platinum-alumina Catalyst AMERICAN CYANAMID co. British Patent 894,412

A platinum-alumina reforming catalyst having improved crush strength retentive properties is made by commingling dried ageing alumina, capable of conversion to eta alumina on calcina- tion, with a platinum compound and aluminium chloride, drying the mixture, forming it into pellets and calcining the pellets. The platinum compound is present in proportion of 0.05-10/0 of

optical pyrometer was used for temperature measurement. Tables are given which relate e.m.f.s in mV with temperatures in degrees F from 32' to 3800°F and with temperatures in degrees C from oo to 2100°C.

A New Method for the Determination of Temperature from the Resistance of a Standard Platinum Resistance Thermometer S. ALTENBURGER, Feingerate Techn., 1962, 11, (3), 116-117

The method described for the determination of temperatures in the range on to 630.5"C requires the knowledge of resistance values of the Pt resistance thermometer at only three fixed points. The calculation of thermometer constants and the measurement of resistance at the ice-point are unnecessary.

A Note on Platinum: Platinum-Rhodium Thermocouple Uncertainty w. E. BOSTWICK, I.R.E. Trans. Nucl. Sci., 1962,

Results are given of tests carried out to determine the effect different types of junction have on the "uncertainty" of temperature measurement of Pt : 10% Rh-Pt thermocouples in the range r p o " to 28oo"F. Crimped, twisted, hydrogen arc-welded and resistance welded junctions were investigated. Hydrogen-arc welding was found to be unsatisfactory.

Thermocouple Materials F. R. CALDWELL, Nat. Bur. Stds. Monograph 40, Mar. I, 1962, 43 pp. LVaterials considered for thermocouple wires include noble metals and their alloys, base metals and their alloys, refractory metals, carbon and carbides. Among the noble metal combinations described are Pt : Rh-Pt, Rh-Pt : Rh-Pt, Ir : Ir- Rh, Pd : Ir-Pt, and Au-Pd : Au-Pt-Pd. Pertinent chemical, physical and mechanical properties of the separate elements are given and limitations of the thermocouple wires as to range, stability and accuracy are discussed. (128 references)

NS-9, (I), 253-259

platinum based on dry wt. of catalyst and the aluminium chloride in proportion of 0.25-2.576.

Fuel Cell GENERAL ELECTRIC co. British Patent 894,530

A combination electrode structure and electrolyte for a fuel cell is formed of a hydrated ion exchange resin membrane having a gas adsorbing metal electrode embedded in each of the two major surface layers of the membrane. The electrode


consists of platinum or palladium adsorbed on activated electrically conductive carbon.

Catalyst ENGELHARD INDUSTRIES INC. British Patent 894,612 A catalyst is made of platinum, palladium or rhodium supported on an asbestos cloth carrier. Suitable for use in catalytic heaters and purifiers.

Manufacture of Carbonyl Compounds CONSORTIUM FUR ELEKTROCHEMISCHE INDUSTRIE G.m.b.H. British Patent 895,843 Carbonyl compounds are made by treating an organic compound containing one or more carbon-to-carbon double bonds and one or more hetero atoms with an aqueous solution of a platinum group metal compound at oo-z50cC.

Zirconium Alloy METALLGESELLSCHAPT A.G. British Patent 896,569 An alloy which is highly resistant to corrosion by water and steam at high temperatures and has a low neutron absorption cross-section consists of 0.05-1.5 ?L palladium and remainder zirconium. Minor additions of niobium, iron, chromium, nickel and/or beryllium may be included.

Electrode Structures IMPERIAL CHEMICAL INDUSTRIES LTD. British Patent 896,912 An electrode structure is formed of a sheet of anodically polarisable metal, e.g. titanium, tantalum or niobium or their alloys in the form of expanded mesh, to the surface of which is secured a platinum group metal (platinum, rhodium or a Pt-Rh alloy). A busbar is secured along one edge of the sheet.

Electrodeposition of Platinum and Palladium JOHNSON, MATTHEY & CO. Lm. British Patent 897,690 A platinum or palladium plating bath consists of an aqueous solution of a complex nitrito-platinite or nitrito-palladite compound of given general formula. Numerous examples are given, the preferred bath comprising dinitritosulphato platinous (or palladous) add H,Pt (or Pd) (NO,),. SO,. Methods of preparation disclosed.

Catalyst for Hydrogen and Oxygen Com- bination U.S. ATOMIC ENERGY COMMISSION British Patent 897,808 A catalyst for combining hydrogen and oxygen in a thorium oxide slurry is made by forming a thorium oxide sol in an aqueous medium containing 0.05 g (or more) of palladium nitrate per g of thorium oxide and then contacting the sol with gaseous hydrogen until the sol is converted to a flocculated suspension, the resulting suspended solids being recovered.

Platinum Catalysts AMERICAN CYANAMID co. British Patent 898,395 Platinum-alumina reforming catalysts are made by impregnating aged alumina (constituting 20-80'j/~ of the h a 1 alumina content of the catalyst) with a halogen-containing compound to add 0.1-0.50/; of the compound, mixing this alumina with dry aged and unimpregnated alumina (constituting 80-20°,; of the final alumina content of the catalyst), commingling this mixture with a solution of a platinum compound sufficient to give o.05-1~; of platinum in the final catalyst, drying, pelleting and calcining the pellets.

Oxidation of Olefines to Aldehydes, Ketones and Acids FARBWERKE HOECHST A.G. British Patent 898,790 In the production of aldehydes, ketones and/or acids corresponding to the aldehydes, a hydrocarbon containing an olefinic double bond is contacted in a neutral to acid medium with molecular oxygen andlor an oxidising agent, water and a salt of palladium, iridium, ruthenium, rhodium or platinum in the presence of a redox system.

Catalysts THE BRITISH PETROLEUM CO. LTD. British Patent 898,972 A catalyst is made by impregnating a refractory oxide containing a platinum group metal with a solution of aluminium halide in an organic water-free solvent, which is subsequently removed. Alumina, aluminium chloride and 0.01-s% by wt. of platinum group metal are used.

Preparation of Cyclo-hexylsulphamic Acid ABBOTT LABORATORIES British Parent 898,988 Cyclohexylsulphamic acid and salts thereof are prepared by hydrogenating phenylsulphamic acid and its salts in the presence of ruthenium as a catalyst.

Catalyst ENGELHARD INDUSTRIES INC. British Patent 899,OO9 A supported ruthenium catalyst is promoted with another platinum group metal, e.g. platinum, rhodium or palladium, the ruthenium content being at least 20 wt.% and up to 95 wt.% of the catalytically active metal. Stated to be advantageous in the hydrogenation of ketones and aldehydes.

Isomerisation of Paraffin Hydrocarbons THE BRITISH PETROLEUM co. LTD. British Patent 899,378 A fraction boiling in the range C4-400"F and containing both aromatic and paraffin hydrocarbons is treated to remove most of the aromatics and the aromatic-free fraction is then contacted


in the presence of hydrogen with a catalyst comprising an aluminium halide and platinum or palladium on a refractory oxide support to cause the paraffins in the fraction to be converted into paraffins having a higher degree of branching by isomerisation.

Hydrogenation of Acetylenes IMPERIAL CHEMICAL INDUSTRIES LTD. British Patent 899,949 Acetylenes are selectively hydrogenated in the presence of olefins by contacting a mixture of at least one acetylene, at least one olefin and hydrogen, sufficient to hydrogenate the acetylenes to olefins, with a catalyst composed of palladium (more than O . I O / ~ but not more than 176) supported on sctivated alumina.

Oxidation of Organic Compounds ENGELHARD INDUSTRIES INC. British Patent

An olefin, N-alkyl substituted aliphatic amide or cyclic ether is oxidised to, respectively, an aldehyde, ionide or lactone by reacting it with ruthenium tetroxide at a temperature at most not much greater than ambient temperature, e.g. o-2o0C, and in a solvent inert to the action of the tetroxide. The solvent may be water, carbon tetrachloride, chloroform or acetone.

Decomposition of 1,l-Dimetliylhydrazine ENGELHARD INDUSTRIES INC. British Patent 900,453 Unsymmetrical dimethylhydrazine is decomposed by contacting it with a platinum group metal catalyst, supported on a carrier, such as asbestos.

Combustion Equipment ROLLS-ROYCE LTD. British Patent 900,765 A combustion stabilising device for use with combustion equipment for gas turbines is formed of a V-section member disposed in the combustion space, the sides diverging in the direction of gas flow forming a channel open in the down- stream direction and a foraminate platinum or platinum alloy catalyst element extending across the channel.

Coating for Metals COMPAGNIE FRANCAISE THOMSON-HOUSTON British Patent 901,292 A protective coating is formed on oxidisable metals by first electrodepositing a layer of rhodium and then a layer of silver. The thickness of the rhodium layer is such that the diffusion of the silver and the base metal through this layer is negligible even during heating.

Removal of Acetylene from Gases

G.m.b.H. British Patent 902,136 Acetylene and/or other compounds containing at

900,107

CONSORTIUM F'& ELEKTROCHEMISCHE INDUSTRIE

least one carbon-to-carbon triple bond is/are removed from a gas by catalytically contacting the gas with an oxidising agent, e.g. oxygen, in the presence of a platinum group metal compound, preferably a palladium compound, at 5O"-I7Ooc.

Brazing Alloy GENERAL ELECTRIC co. British Patent 902,521 A high temperature brazing alloy contains 15-40 wt.4, chromium, 5-35 wt.:; palladium and balance nickel.

Silver Alloy U.S. ATOMIC ENERGY COMMISSION German Patent

A silver alloy having high neutron-absorption and strength properties contains 0.5-I.5°/0 platinum, ruthenium, rhodium, osmium or palladium] z-zoo/, indium, with, if desired, up to 10% cadmium and balance of not over 8596 silver.

Thermoelement Alloy

German Patent 1,119,933 A gold-palladium-vanadium alloy containing 59-68 wt.9/, gold, 30-39 wt.7; palladium and 0.7-2.5 wt.:h vanadium is used as the positive limb of a thermoelement.

Gold Alloys

German Patent 1,121,339 Workable gold alloys for electric conductors with high specific resistance, such as potentiometer wires, arc made of 1-5~6 titanium 3 - 8 O ; iron and remainder gold and palladium.

Method of Making Cyanogen ROHM & HAAS G.m.b.H. U.S. Patent 3,031,265 Cyanogen is made by contacting hydrogen cyanide at a t least 300°C with a platinum group metal catalyst.

Catalyst Manufacture UNIVERSAL OIL PRODUCTS co. U.S. Patent

A catalyst is made by treating a refractory oxide- platinum group metal (in a reduced valence state) composite with a hydrohalide at 5o0-65o0C, then vaporising a Friedel-Crafts metal halide into the composite and heating the latter at above 400°C to remove any unreacted metal halide.

Catalysts AMERICAN CYANAMID CO. U S . Patent 3,032,512 A platinised alumina catalyst is made by leaching pieces of active alumina by contact with a mixture of nitric acid and hydrochloric acid of sufficient strength to react with alumina until 2-15% thereof is solubilised, washing the pieces with water and then impregnating them with an aqueous solution of chloroplatinic acid.

I,I 19,522

DEUTSCHE GOLD-UND SILBER-SCHEIDEANSTALT

DEUTSCHE GOLD-UND SILBER-SCHEIDEANSTALT

3,031,419

Platinum Metals Rev., 1962, 6 (41, 162

AUTHOR INDEX TO VOLUME 6

Page

Adams, R. B. 38

Mrossman, S. 159 Aft, H. 158 Akamatsu, A. 78

Alexander, B. T. 34 Ali, S. I. 79, 159 Altenburger, S. 160 Andersen, H. C. 33 Anderson, R. B. 34 Andreeva, V. V. 76 Andrussow, L. 35 Angus, H. C. 122, 123 Aronsson, B. 76, 153 Arthur, J. R. 155 Asanov, U. A. 31 Aselius, J. 76 Aston, J. G. 116, 155 Ankrust, E. 117

Adamec, J. B. 33

Adler, S. F. 80

Alekseev, G. N. 37

Bacquias, G. 156 Baker, R. H. 34 Barber, C. R. 123 Baron, V. V. 75 Barton, J. C. 77, 116 Batey, H. 32, 37 Batliner, D. J. 34 Baun, W. L. 75 Beattie, R. W. 52 Beck, F. 33 Becker, E. W. 121 Bell, W. E. 32, 116 Bel’skii, I. F. 122 Benkeser, R. A. 80 Benson, R. E. 36

Bertolacini, R. J. 79 Betteridge, W. 156 Bewig, K. W. 117 Bhattacharyya, K. K. 94

Berger, C. V. 34

Bianchi, G. 34 Birthler, R. 35 Bishop, C. R. 32, 11 7 Blackburn, G. F. 160 Blakely, J. M. 117 Blennemann, D. 79 Blume, H. 158 Bond, G. C. 12, 122 Boreskov, G. K. 121 Boreskova, E. G. 32 Bostwick, W. E. 160 Bradley, D. 77 Brandon, D. G. 95 Breiter, M. W.

77, 118, 156 Brock, T. W. 78 Brown, C. A. 156, 157

Page Brown, H . C. 156, I57 Bryant, R. T. 116 Bryla, S. M. 155 Burrous, M. L. 80 Bursian, N. R. 81

Cable, J. W. Cahen, R. Cairns, E. J. Caldwell, F. R. Canale, A. J. Caprioglio, G. Casanova, J. Caswell, L. R. Chalk, A. J. Chaston, J. C. Chon, H. Christensen, B. E. Chu, B. Ciapetta, F. G. Claassen, H. H. Clemens, K. H. Coles, B. R. Connor, H. Coonradt, H. L. Craik, D. J. Crouzy, F.

154 121 77

160 135 34 28

120 119 I55 155 158 159 33 32 81

154 130

33, 36 31 35

Darling, A. S. Davtyan, 0. K. Dehye, P. De Rosset, A. J. Dettner, H. W. Dobson, N. A. Douglas, D. L. Douglas, R. W. Dreger, L. H.

60, 106 36, 120

159 34

119 120 77 58 77

Eglinton, G. 120 Elkins, J. S. 79 Endter, F. 9 Entwistlc, A. G. 77

Feldman, C. 155 Ferro, R. 115 Finnie, L. N. 11 5, 154

Fisher, R. A. 76, 155 Francis, A. V. 155 Francis, D. 91

Freifelder, M. 35, 36, 81

Frumkin, A. N. 48

Fischer, W. R. 33

Fraser, D. S. 34

Friedrich, J. P. 34

Garwood, W. E. 36, 119 Cault, F. G. 79, 159

Page Geballe. T. H. 116

Gilman, S. 156 Glover, B. M. 86 Gmohling, W. 153

Gerischer, H. 33

Graham, D. 36, 120 Green, B. 122 Green, W. J. 33 Grigor’ev, A. T. 75, 153 Gruber, H. L. 119 Gryaznov, V. M. 37, 121

Hadfield, D. 2

Hafner, W. 120 Haensel, V. 31

Hagmann, D. 76, 153 Hahn, P. M. 149 Haines, H. W. 159 Hall, J. A. 123 Halpern, J. 78. 120 Halpern, T. 77 Hampson, R. F. 32, 155 Hansen, R. S. 155 Harrod, J. F. 119 Hartelins, C. C. 154 Hartley, C. S. 75 Haul, R. 79 Herrmann, R. A. 80 Herrschaft, D. C. 33 Hewett, W. A. 135 Heyns, K. 37 Hirota, K. 157 Hiskey, R. G. 79 Hopkins, M. R. 37 Houston, R. J. 35, 158 Hughes, T. R. 158 Humphreys, J. G. 20 Hurwitz, A. 35

Ilschner-Gensch, C. 33 Ioffe, I. I. 121 Ismail, S. M. 159 Izumi, Y. 78

Jackson, J. James, B. R. Jankowska, H. Jelley, R. Joachim, K. Johnston, A. E. Johnston, C. Jones, F. Llewellyn Juchniewicz, R.

31 78

118 20

123 157 68 37

100

Kagle, B. J. 31 Kammer, E. W. 116 Kavtaradze, N. N. 32 Kealy, T. J. 36

Page Kemhall, C, 79 Kessler, R. W. 121 Khodakov, Yu. S. 81 Khotinskaya, A. N. 31 Kieffer, B. 115 Kirchner, S. 91 Kirner, I<. 147 Kleinle, A. 119 Klemens, P. G. 77 Klemm, W. 31 Klimova, N. V. 121 Klochko, M. A. 15 Kluksdahl, H. E. 35 Kobozev, N. I. 35 Kokotailo, G. T. 36 Kolbel, H. 94 Kondrat’ev, D. A. 121 Koster, W. 76, 17 Kouvel, J. S. 154 Kozakevitch, P. 76 Krier, C. A. 58 Kronig, W. 157 Krupp, H. 136

Kuz’min, R. N. 115 Kuprina, V. V. 75

Larson, 0. A. 36 Lefrancois, P. A. 80 Lewis, F. A. 22, 71, 116 Liberman, A. L. 81 Lindsay, W. T. 155 Loebich, 0. 119 Logie, H. J. 31 Lowenthal, G. C. 77 Lncas, L.-D. 76 Lux, H. 31

McDonald, D. 112 MacDonald, D. K. C.

116 MacIver, D. S. 36 MacMillan, D. 157 MacNamara, E. L. 78 Maisel, L. 78 Mahn, J. G. 76 Manakin, B. A. 36

Margrave, J. L. 77

Maslyanskii, G. N. 81 Matthias, B. T. 11 6 Maxted, E. B. 79, 159 Medvedeva, Z. S. 75

Markhal, J. 121

Mars, P. 34

Menzel, D. 75 Merl, W. 37

Mes’kin, V. s. I54 Merten, U. 32

Metson, G. H. 37, 160


Page Miles, J. J. 119 Minachev, Kh. M.

81,121 Minatschew, H. M. 159 Minenko, V. 1. 33 Misyuk, E. G. 120 Mitacek, P. 116, 155 Mooi, J. 157 Mosevich, I. A. 155 Moy, J, A. E. 157 Muan, A. 117, 154 Miiller, G. F. P. 156 Miinzing, J. 158 Murphy, W. K. 153 Murthy, M. K. 38 Myers, C. G. 119 Mykura, H. I I7

Narath, A. Nathans, R. Neilson, T. Nethercot, W. Nevitt, M. V. Nicholson, M. E. Nicolau, C. Nishimura, S. Nitschke, E. Northrop, R. C. Nuirez, F.

27 154 121 10

115 116

34,119 79

121 79 31

Page Plank, C, J. 36 Polyakova, V. P. 75, 153 Pospelova, T. A. 35 Powell, R. W. 138 Pravoverov, N. L. 76 Preiser, H. S. 57 Price, E. G. 155 Prinz, W. 96

Quiney, E. D. 80

Rabenhorst, H. 136

Rader, C. P. 156 Rambaldi, G. 115 Rao, K. K. 116, 154 Raschcnzewa, M. A. 159 Raub, E. 75 Rausch, M. D. 117 Reinacher, G. 148 Renauer, E. 31 Rhoda, R. N. 33, 118 Rhys, D. W. 156 Richardson, D. A. 49 Riekert, L. 158

Rinehart, R. E. 46 Rinker, R. G. 80 Roberts. R. W. I58

Rabo, J, A. 33

Rindone, G. E. 81

Robinson, R. M. 36, 81 Obrowski, w- 969 154 Rohrer, J. C. 35, 159

153 Rooney, J. J. 159 Oriani, R. Ovchinnikova, E. N. 36 Rosenstock. p. D. 35

Page, G. C. Pantani, F. Panteleimonov, L Pask, J. A. Pearson, W. B. Pement, F. W. Petrov, S. M. Pettit, G. R. Philpott, J. E.

Pickart, S. J. Pickert, P. E.

42,

122 I17

r . A. 153 38

116 155 33

122

78, 144 I54 33

Rowbottom, S. 80 Rozelle, R. B. 119 Rudnitskii, A. A. 31, 75 Rudy, E. 115

Sakaida, R. R. 80

Savitskii, E. M. Sauvage, J.-F. 34

75, 76, 115 Schewe, J. H. 120 Schindler, A. I. 116 Schnabel, K.-H. 80, 119 Schneidereith, G. 137

Page Scholten, J. J. F. 122 Schuetz, R. D. 120 Schwabe, K. 118 Searcy, A. W. 154 Selig, H. 32 Selin, T. G. 157

Shafrin, E. G. 117

Sherwood, P. W. 80 Shiratori, H. 156 Shishakov, N. A. 31, 76 Shnabel’, K.-Kh. 81 Shoobert, G. W. 92 Shuikin, N. I. 78, 122 Sinfelt, J. H. 159

Smith, G. W. 159 Smith, H. A. 156 Smith, H. P. 46

Solomon, E. 80

Sergienko, R. I. 154

Shamma, M. 35

Smidt, J. 79, 120

Smith, W. M. 120

Spector, M. L. 37 Stein, K. C. 34 Steingaszner, P. 35 Stenberg, E. 153 Stem, E. W. 37 Stern, M. 32, 117 Stewart, P. J. 126 Stocker, J. H. 159 Stone, G. R. 81 Strel’nikova, Zh. V. 36

Tagami, M. Taylor, A. Taylor, B. Taylor, J. C. Taylor, R. W. Teeter, H. M. Terada, K. Terekhova, V. F. Thatcher, D. N. Thomas, C. L. Thomas, 0. H. Thomson, J. R. Thomson, S. J. Tiilikka, A.

116 31

155 154 154 34

115 75

159 158 157 115 159 27

Page

Trosman, E. A. 36 Tye, R. P. I38 Tylkina, M. A. 115, 153

Tomassi, W. 118

Tytell, B. H. 57

Ueda, T. 157 Urbain, G. 76

Van de Mond, Th. Van Montfoort, A. Vasilevich, A. A. Venker, P. Vert, Zh. L. Vincent, G. L. Voitovich, R. F. Voorhies, A. Voss, G.

34 122 121 34

155 81

115 120 157

Wadsworth, M. E. 80 Walker, R. F. 32, 155 Walkiden, G. W. 122 Walter, S. 121 Webb, G. 12, 122 Weinstock, B. 76 Weller, H. 80 West, R. 157 Wicke, E. 32 Wimber, R. T. 80 Wid, T. M. 77 Wojcicki, A. 117 Wollan, E. 0. 154 Wood, H. C. S. 121

Yagodovskii, V. D. 37, 121

Zajcew, M. 158 Zegler, S. T. 115 Zhdanov, G . S. 153 Zhuravlev, N. N.

115, 153 Zingery, W. L. 77 Zisman, W. A. 117 Zuehlke, R. W. 116 Zwingmann, G. 154


SUBJECT INDEX TO VOLUME 6 a=abstract Page Aromatic Hydrocarbons, production from

petroleum 86. 157

Bursting Discs, Pt, protection of chemical plant 42

Catalysis,

Catalysts,

behaviour of Pt mctals, a 122 in petroleum refining, a 158

Adams’, history of 150 H,PtCls, additon of HSiCI2 to olefins, a 157 In petroleum industry, recent U.S.A. patents

U 80 Ir/C, dehydrogenation of dihydrofurans, a 122 Noble Metal, hydrocracking, a 120 Os/Al,O,, hydrogenation of unsaturated

hydrocarbons 12 Os/C, dehydrogenation of dihydrofurans, a 122 OsO,, oxidation of olefins, a 122 Palladium, black, isotopic exchange of

g-xylene with D,O, a 157 detoxication of, a 159 film, conversion of cyclohexene and

cyclohexadiene, a 121 exchange of n-hexane and deuterium, a 79 exchange of polymethylcyclopentanes

with deuterium, a 159 136 36

activity in hydrogenation, a 19 surface area of, a 122

158 hydrogcnation of Cs-fractions, a 157 hydrogenation of linolenate, a 157 isomerisation of naraffins. a 157

Raney-type, for fuel cell electrodes supported, activation by irradiation, a

Pd/AlsOa, hydrogenation of CI-fraction, a

oxidation of CO:a 34.37 oxidation of CH,, a 34

Pd/BaSO hydrogenation of acetylenes, a 120 hydrogenation of C,H,COCI. a 159 h$drogenation of cycloalkanes, a 34 nuclear reduction of pyrimidines, a 158

Pd/BIOI/AlaOh isomerisation of paraffins, a 157 Pd/CaCO,, hydrogenation of acetylenes, a 120

120 Pd/C, activation by irradiation, a dehvdrownation of a. R-unsaturated . .

lictanis, a hydrogenation of acetylenes, a hydrogenation of cycloalkanes, a hydrogenation of fatty acids, a hydrogenation of a-keto acids, a hydrogenation of linolenate, a hydrogenation of nitrosamines, a nuclear reduction of pyrimidines, a production of margarine, a reduction of aromatic nitro-

compounds, a Pd/SiOz gel, synthesis of H,Op, a PdjThO,, detoxication of, a Pdlzeolite. isomerisation of C , and C,

35 120 34 34 79

157 159 158 IS8

121 35 159

paraffins, a 33 Pd/Re/Al,.Oa, isomcrisation of alkanes, a PdCI.. oxidation of olefins. a

159 79, 120 - _ _

&idation of propylene, a 80 PdCln-olefin complexes, vinylation, a 37 Pd(OH),/C, hydrogenation of a-keto acids, a 79 Platinum, black, isotoplc exchange of

p-xylene with D20. a 157 oxidation of SO,, a 36

34 decomposition of acid HeOz solutions, a

film, conversion of cyclohexene and evaporatlon rate, a 35

cyclohexadiene, a 121

hydrogen isotope exchange, a 121 exchange of polymethylcyclopentanes

with deuterium, a 159

thermal pretreatment of, a 31


Catalysts ( c o d . ) Page gauze electrode, a 33 hydrocracking, a 119 hydrogenation of CeH,, a 159 hydrogenation of unsaturated com-

pounds, a 157 oxidation of SO,, a 36 petroleum refining, a 157 platinised, electrochemical oxidation

and hydrogenation of, a 120 Raney-type, for fuel cell electrodes reduction of aqueous CoS0,-NH.

136 . .

(C,HJO,) solufions, a 80 reforming, a 35

effect of S on activity and selectivity, a 81 reforming and hydroisomerisation, a 37 supported, activation by irradiation, a 36

oxidation of CO, a 33 oxidation of ethylene glycol, a 121 reforming, a 35

synthesis of HCN 9 synthesis of polysaccharides, a 37 wire, decomposition of HCOOH, a 158

and CO by, a 119 Cs-dehydrocyclisation of iso-C sH, a 119 crystallite size, a 36 dehydrocyclisation of a-heptane, a 35 dehydrogenation and dehydrocyclisa-

tion of hydrocarbons, a 159 effect of y-irradiation on activity, a 81 hydrogenation of linolenate, a 157 isomerisation of paraffins, a 157 isomerisation of n-CsHlz, a 121 light transmission and scattering of, a 159 oxidation of enamelling fumes, a 34 oxidation of CHI, a 34 poisoning by S, a 121 reforming, a 157

in W. Europe 86 valence state of Pt, a 79

Pt/AlaOa/Ba08, isomerisation of paraffins, a 157 Pt/Al,Os/C1, sintering of, a 80 Pt/A1,Oa/SiO, hydrocracking, a 33,36 PtCdO, decomposition of H,02, a 36 Pt/C, activation by irradiation, a 120

80 dehydrocyclisation of iso-C,H!,, a 80

activity, a 81 heavy water production, a 121

change, a 79

Pt/Alz03, adsorption of hydrogen, oxygen

addition of SiHCI, to acetylenes, a

effect of method of preparation on

hydrogen-liquid NHa isotope ex-

hydrogenation of linolenate, a 157 hydrogenation of nitrosamines, a 159 isomerisation of paraffins, a 157 temperature dependence of activity, a 34

Pt/C/Al,Oa, Cs-dehydrocyclisation of iso- C,H,,, a 119

Pt/C/SiO,, Cs-dehydrocyclisation of iso- C ~ H I ~ , a 119

Ptloxide supports, activity in hydrogenation. a 79

Ptlrare earth oxides, decomposition of men.. 159 --‘- <, -

Pt/SiO,, Ca-dehydrocyclisation of iso- CsHis, a 119

hydrogen-liquid NH isotope exchange, a 79

78 isomerisation of paraffins, a IS7

Ptlsilk. oreoaration and activity, a ’ proberiies, a 78

80 Pt/Ni/AI,O, decomposition of NO, a Pt-Pd, supported, oxidation of ethylene

Pt(I1)-Olefin Complexes, addition of Si-H, a I19

PtOl, Adams’ 150 hydrogenation of aromatic hydro-

carbons, a 156

glycol, a 121

165

Catalysts (contd.) Page hydrogenation of disubstituted

benzenes, a 1 20 hydrogenation of linolenate, a 157 nuclear reduction of piperidines, a 158

8, 1 19 hydrogenation and dehydrogenation, a 34 hydrolysis,of NaBHI,, a. 156 polybutadienc prcparation 135 preparation by NaBH, reduction, a 156

on A1,O3, conversion of cyclanes and

Platinum Metals, in fuel cell electrodes,

synthesis of HCN,. a 35

hydrocarbons, a 122

alkanes, a 78 hydrogenation of unsaturatcd

alkanes, a 78 158

exchange of n-CsHlr and deuterium, a 79 exchange of polymethylcyclopentanes

with deuterium, a 159 Raney-type, for fuel cell electrodes 136

Rh/Al,Oy, hydrogenation of N-benzylidine-

hydrogenation of or-substituted benzyl alcohols, a 159

Rh/C, dehydrogenation of dihydrofurans, a 122 hydrogenation of N-benzylidinebutyl-

amine, a 35 hydrogenation of nitrosamines, a 159 hydrogenation of substituted pyridines, a

36, 81 RhCIJ, polymerisation of 1,4-butadiene 46 Rh(NOs)3, polymerisation of 1,4-butadiene 46 Rh-Pt Oxide, preparation, activity and

selectivity, a 79 Ruthenium, hydrogenation of pyridines, a 81

synthesis of paraffin waxes 94 RulA1.0,. hvdrogenation of unsaturated

on SiOa gel, conversion of cyclanes and

Rhodium, film, cracking of C,H,

butylamine, a 35

hydiocarbbns - 12 Ru/C, dehydrogenation of dihydrofurans, a RudCO).. carbonvlation of allene. a

122 36 , -.

RuC12, homogen&us hydrogenation of

RuCI,, carbonylation of allene, a 36 hydration of acetylenic compounds, a 78 polymerisation of butadiene 135

surface measurements of, a 158 57

olefinic compounds, a 120

Cathodic Protection, effect on cavitation damage methods and applications, a 122 Pt anodes for, a 122

Deuterium, exchange with polymethylcyclo-

Diffusion Cells, for hydrogen purification, a pentanes, a 159

156 47, 130 Ag-Pd, for hydrogen purification

Electrical Contacts, Cu-Pd, material transfer properties, a 37 Pt and Pd. metal transfer, a 37

123 Pt Metals, surface films on, a 122 transfer-inductance characteristics of 10

Iridium, from aqueous solution, a 78 from molten cyanide electrolytes, a 118

Palladium, a 78, 119 for electrical engineering, a 119 on telephone plugs and sockets 52

Platinum, for electrical engineering, a 1 I9 from molten cyanide electrolytes, a 118 on thermionic grid material 147

Noble Metals, properties and applications, a 156 Rhodium, for electrical engineering, a 119

Ruthenium, from molten cyanide electrolytes, a 118

118 in spark plugs 92

Rh and Pd, electrodeposited, a

Electrodeposition of

thickness measurements, a 78

Electrodes, Iridium, hydrogen adsorption by, a

Electrodes (contd.) Page Palladium, in fuel cells 136 PI-H, coexisting a- and 8-phases, a 156 Pd-H-H,, hydrogen overvoltage and hydro-

Platinum, adsorption of anions on, a 118 anodes, for cathodic protection, a 122

effect of a x . on corrosion of 100 oxidation of CHIOH, a 156 surface phenomena at 48

black, a 118 in Cll-Cl-H,O system, a 118

effect of organic molecules on adsorp-

in fuel cells 136 hydrogen adsorption by, a 118 reduction of chemisorbed oxygen on, a 118 in silicate melts. a

gen diffusion, review 22

tive properties, a 77

in the solion, a

in solutions containing C1, a Pt/C, powder, a

Pt-clad Ta. anodes. for cathodic urotec- tion studies

Pt/Ti, anodes, for cathodic protection, a effect of a.c. on corrosion of

Pt-Pd, anodes, for cathodic protection. a Platinum Metals, in hydrogen-oxygen fuel

Rhodium, in fuel cells hydrogen adsorption by, a

Rh-Pd, hydrogen overvoltage at, a Electroless Plating of

Palladium, a Platinum Metals, a

cells, a

Fuel Cells, low temperature Furnace, for HCN synthesis

Pt-wound, for glass devitrificatiou studies

Glass, effect of Pt nucleation. a fibre manufacture, a '

Li20.4SiO, effect of Pt as a nucleating agent, a

tubing, manufacture of wetting of Pt, a

33 123 118 118

57 122 100 122

77 136 118 77

119 119

8 9

49

38 81

81 59 38

Heavy Water, pilot-plant production of, a 121 47, 130

CeHot a 156, 159 CbHbCOCI, poisoning, a 159

Hydrogen Purification, diffusion ccll for Hydrogenation of . acetylenes, a 120

C=N linkage 35 disubstituted benzenes, a 120 fatty acids, a 34 fatty oils, a 158 methyl linolenate, a 157 nitrosamines, a 159 olefinic compounds, a 120 polymethylbenzenes, a 156 substituted pyridines, a 36 CeHbCHs, u 156 unsaturated compounds, u I57 unsaturated hydrocarbons 12,122

Hydrogen Cyanide, synthesis 9 Hydrogen Peroxide, synthesis, a 35

Immersion Plating, of Pd Iridium, adsorption of hydrogen, C2Hs, C r H ,

sources for y-radiography spark plug electrodes for aero engines thermal conductivity and electrical resistivity vapour pressure, a

Iridium-Boron, crystal structure, a Iridium-Chromium, superconductivity, a Iridium-Magnesium, constitution, a Iridium-Palladium, constitution, a

and C I H z on, a

Iridium Alloys,

144

155 1 1 92

138 32

153 116 115 153

Platirzum Metals Reu., 1962, 6 9 (41, 166

Iridium Alloys (contd.) Page Iridium-Palladium-Silver, constitution and

propcrties, a 75 Iridium-Silicon, structure and composition, a 11 5 Iridium-Thorium, crystal structure of ThIr, a 1 15

Iridium Carhonyl Complexes, substitution and exchange reactions in, a 117

Iridium Dioxide, oxygen pressures of formation 137

Magnets, permanent Co-Pt in flow meter

56 98

Osmium, thermal conductivity and electrical

Osmium Alloys. resistivity 138

Osmium-Boron, crystal structure, a 153 Osmium-Rhenium, constitution, a 153 Osmium-Ruthenium, constitution, a 153 Osmium-Silicon, structure and composition, ( I 11 5 Osmium-Tungsten, constitution, a 31

1 17

c o , a 33, 34, 37 enamelline fumcs. a 34

Osmoceue, ring substitution reactions of, a Oxidation of

ethylene dycol, a CHI, a

121 34

122 80 36

Palladium, adsorption of CO, a 32 coatings, properties, a 119 electrical properties, a 76 heat of adsorption of hydrogen on, a 155 hydrogen diffusion and solubility in, a 156 immersion plating of I44 molten, density, a 76 sorption of NO, a 116 surface oxidation, a 76 thermal conductivity and electrical resistivity 138 vapour pressure, a 32, 155

156 Palladium-Cadmium, electrical and magnetic

Palladium Alloys, for brazing, a

properties, a 76 Palladium-Cobalt, magnetic properties of

PdrCo and PdCo, a 154 Palladium-Copper, contact properties, a 37 Hall effect, a 116 heat of formation, a 153

thermoelectric properties, low temperature, a 116 Palladium-Deuterium, phase diagram, a 32 Palladium-Gold, effect of plastic deformation

on resistivity, a 31 electrical and magnetic properties, a 76 electrical resistance and Hall constant, a 77

high-temperature brazing, a 33

high-temperature brazing, a 33 Palladium-Gold-Nickel, constitution and

properties, a 153

resistance of. a 155 Palladium-Hydrogen, a-Pd-H, electrical

electrical resistance in aqueous solutions, a 116

phase diagram, a 32 physical properties, a 116 structure of a- and B-phase hydrides, a 155

Palladium-Indium, electrical and magnetic properties, a 76

Palladium-Iridium, constitution, a 153 Palladium-Iridium-Silver, constitution and

Palladium-Iron, magnetic properties of PdaFe and PdFe, a 154

oxidation of, a 117 thermoelectric urooerties. low tem-

properties, a 75

~- perature, a 116

75 Palladium-Iron-Cobalt, phase changes in, a Palladium-Manganese, thermoelectric

~- perature, a 116

75 Palladium-Iron-Cobalt, phase changes in, a Palladium-Manganese, thermoelectric

properties,-low temperature, a 116 Palladium-Mercury, crystal structure, a 115

Palladium Alloys (confd.) Page Palladium-Molybdenum, electrical and

magnetic properties, a 76, 154 Palladium-Molybdenum-Titanium, corrosion

resistance and mechanical properties, a 117 Palladium-Nickel, high-temperature brazing, a 33

thermoelectric properties, a I16 Palladium-Niobium, constitution and prop-

erties, a 75 electrical and magnetic properties, a 76

Palladium-Rhodium, electrical and magnetic properties, a 76

Palladium-Rhodium-Platinum. tensile and creep properties 148

and properties, a 31 Palladium-Rhodium-Silver, constitution

Palladium-Ruthenium, electrical and map- netic properties, a 76

structure and properties, a 154 Palladium-Silver, constitution and uroucr-

~~

ties, a 76 electrical and magnetic properties, a 76 electrical resistivity. a 154 Hall effect, a 116 heat of adsorption of hydrogen on, a 155 heat of formation, a 153

hydrogen diffusion and solubility in, a 156 in hydrogen diffusion cells 41, 130 for hydrogen purification 47, 130 wetting properties, a 33

perties, a 75

high-temperature brazing, (1 33

Palladium-Tellurium, constitituon and pro-

Palladium-Tin, thermoelectric propcrties, low temperature, a 116

Palladium-Titanium, corrosion resistance, a 33 Palladium-Tungsten, electrical properties, a 154 Palladium-Zirconium. electrical and mae-

netic properties, a - 76 with Ag, Cd, In, Rh, Ru, Mo, Nb, Zr, or V,

electrical resistance and Hall constant. a 143 Palladium Chlorides, high temperature prop-


. . erties, a 32

Palladium Comolexes. with 6-mercaotonurine. in cancer research ’ 91

metal catalyst, a 120 isomerisation of C s and Cg paraffins, a 33 at Kalundborg, Denmark, a 80 at Misburg, W. Germany, a 80 reforming, a 35

at Erdolwerke Frisia refinery, Emden, a 120

review, a 34 in W. Europe 86

reforming and hydroisomerisation, a 37 117

adsorption of hydrogen, a 32 black, hydrogen and oxygen adsorption by, a 76 bursting discs 42 coating of Mo, diffusion studies 147 coatings, properties, a 119 cores for oxide cathodes, a 37, 160 effect on crystallisation of glass, a 38, 81 films, contact potential in, a 155 gauze, platinised, catalytic hydrogenation

contact, a 33 heats of adsorption of He, Nc, Ar, and Kr

on, a 155 junctions in thermoelectric generator 99 metallurgy of, early experiments recorded

by Casanova 28 mining in Alaska 68 molten, density, a 16

surface tension, a 76 oxidation of, a 31

112 resistivity 77, 138 surface oxidation, a 76 surface properties, a 117 surface structure, study by field ion micro-

Petroleum Refining, hydrocracking, new noble

Platinum, adsorption of fatty amines, a

Percival Johnson’s first paper, 18 12

SCOPY 95

Platinum (conrd.) Page in Telstar satellite 143 thermal conductivity and electrical rcsis-

tivity 138 vapour pressure, a 32 wetting, by fluorinated heptadecanoic

acids, a 117 by glasses, a 38

Platinum/Carbon, hydrogen and oxygen adsorption by, a 76

Platinum Alloys, Platinum-Barium. thermionic work func-

tion, a 32 Platinum-Bismuth, constitution, a 153 Platinum-Calcium. thermionic work func-

tion, a 32

of Crp.JPtn.ir a 154

manent magnets 56, 98 heat of formation, a 153

structure, a 31 Platinum-Copper. heat of formation, a 153

thermoelectric properties, low temperature, a 116

Platinum-Gold, constitution and properties 60, 106

Platinum-Iron, activities of Fe in, a 154 thermoelectric properties, low tcm-

perature, a 116 Platinum-Manganese, magnetic properties

of MnPts, a 154 thermoelectric properties, low tem-

perature, a 116 Platinum-P~lladium-Silver, wetting proper-

heating element for microscope, a

Platinum-Rhodium-Palladium, tensile and

Platinum-Strontium, thermionic work func-

Platinum-Tin, thermoelectric properties,

with Al, Se, Mg, Ca, Sr and Li, prepara-

Platinum Complexes, with 6-mercaptopurinc, in

Platinum Hexafluoride, preparation and pro-

Platinum-Chromium, magnetic properties

Platinum-Cobalt, corrosion resistant per-

permanent magnet, remanence, a 77

ties, a 33 Platinum-Rhodium, emissivity, a 77

78 59

creep properties 148

tion, a 32

low temperature, a 116

tion, a 31

cancer research 91

in manufacture of glass tubing

Platinum-Silver, wetting properties, a 33

Platinum-Tungsten, oxidation of, a 115

perties, a 76 Platinum Metals, effect of molten NaOH and

KOH on, a high-temperature properties prevention of hydrogen embrittlement of

properties and applications, a sensitisers in photographic emulsions

Platinum Metal Alloys, with Si and C, a

Ta, a

31 58

32 '!I A / 154

Polybutadiene, preparation 46 Pyrometers, immersion, in steel temperature

measurement 2

Radiography, WBB as source 11 Resistance Thermometers, platinum, a 8 1

platinum, calibration, a 160 development of, a 123 modified Mueller bridge for, a 123

Rhodium, coatings, properties, a 119 electrodeposited, thickness measurements, a 78 high-purity, temperature coefficient of

electrical resistance, n 155 thermal conductivity and electrical resis-

tivity 138 vapour pressure, a 32, 77

Rhodium-Bismuth, constitution, a 115 Rhodium Alloys,


Rhodium Alloys ( c o d . ) Page Rhodium-Chromium, superconductivity, a 116 Rhodium-Iron, electrical and magnetic

properties of FeRh, a 154 Rhodium-Palladium, electrical and mag-

netic properties, a 76 Rhodium-Palladium-Silver, constitution

and properties, a 31 Rhodium-Platinum, emissivity, a 77

heating element for microscope, a 78 59

sheaths for thermocouples 126 Rhodium-Silicon, structure and composition, a1 IS Rhodium-Thorium, crystal structure of

ThRh,. a 115 Rhodium Carbonyl Complexes, substitution and

exchange reactions in, a 117 Rhodium Chlorides, high temperature proper-

tie$, a 32, 116 Rhodium Hexafluoride, physical and chemical

properties, a 32 Ruthenium, thermal conductivity and electrical

resistivity 138 Ruthenium Alloys,

Ruthenium-Boron, crystal structure, a I53 Ruthenium-Chromium, constitution, a I5

superconductivity, a 116

in manufacture of glass tubing

Ruthenium-Nickel, constitution and properties, a

Ruthenium-Niobium, oxygen solubility in, a Ruthenium-Osmium, constitution, a Ruthenium-Palladium, electrical and mag-

structure and properties, a Ruthenium-Rhenium, constitution and

Ruthenium-Silicon, structure and composit-

Ruthenium-Silver, wetting properties, a Ruthenium-Tantalum, constitution, a Ruthenium-Thorium, crystal structure of

Ruthenium Chlorides, high temperature proper-

RuCl a, complcx formation in aqueous

Ruthenium Dioxide, oxygen pressures of forma-

Ruthenium Hexafluoride. Dhvsical and chemical

netic properties, a

properties, a

ion, a 76,

ThRu, a

ties, a

solutions, a

tion

75 116 153

76 154

115

115 33 75

115

32

117

137 I . -

properties, a 32 1 I7 Ruthenocene, ring substitution reactions of, a

Solion, operating principles and applications, a 124

Tantalum, prevention of hydrogen embrittle-

Temperature Measurement, of gas turbine

of high transient surface ternpcratures in open-hearth steelmaking

Iridium :Iridium-Rhodium, reference tables,

Platinum :Rhodium-Platinum, effect ofjunc-

ment of, by Pt Metals, a

engine exhaust

Thermal Analysis, of grey iron Thermocouples,

a

tion of uncertainty, a gas turbine engine combustion tests in immersion pyrometers in iron foundry open-contact, spring-loaded Pt-clad, for glass studies

properties and limitations, review, a Platinum Metals, a

Rhodium-Platinum :Rhodium-Platinum, calibration

Thermoelectric Generator

32

I26 149

2 20

160

160 126

2 20

149 49 81

160

96 99

Uranium-Fissium Alloys, structure and properties, a 115

168

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