TECHNOLOGY,

years at temperatures encountered in Class H installations.

Adhesives. New high temperature structural adhesives designed especially for use in metal-to-metal bonds were described by S. E. Susman of Narmco, Inc. Of particular importance to the aircraft industry, the principal adhe­sive evolved is based on a combination of acid catalyzed phenolic resin iri combination with butadiene-acryloni-trile rubber. The adhesive is available either as a tape or as a solution, either of which has a storage life of at least three months.

S tandards and Specifications. Ma­terial progress toward establishment of standards for reinforced plastics in vari­ous applications was reported by SPI's standards subcommittees dealing with electrical flat sheet, corrugated sheeting, and piping. The electrical flat sheet subcommittee has been working with a similar group from the National Elec­trical Manufacturers' Association, to­ward development of a standard for an electrical grade, general-purpose glass mat polyester resin laminate, for use in both mechanical and electrical applica­tions. The proposed standard is to be circulated to members of both SPI and NEMA for approval. After approval, it will proceed through conventional NEMA channels to become a NEMA standard and will be published by them.

The subcommittee on corrugated sheeting has concentrated on establish­ment of standards for strength, light transmission, and color stability. Stand­ard test methods are being evolved, in order that all manufacturers may apply uniform tests, enable them to guarantee physical strength in a given application, percentage of light transmission for a given color or weight of a given prod­uct, and in a less definitive degree, re­sistance to degradation of exposure to light over a given period of time. A preliminary polling of manufacturers, users, and others interested in rein­forced plastics pipe showed that some 8 1 % of those replying favored the es­tablishment of standards. Mentioned most often among physical properties for which the establishment of specifi­cations seems desirable were fatigue pressure limit, safe working pressure, burst pressure, axial tensile strength, impact strength, useful temperature range, flexural strength and modulus, water resistance, and heat transfer prop­erties.

Exhibits. Display of reinforced plas­tics items staged in conjunction with the conference reflected almost limitless potential for these materials. Two plas­tic-bodied sports cars now in commer­cial production, the Chevrolet Corvette and the Kaiser-Willys Darrin, were shown along with samples of compo­

nent parts. Also on display was a cus­tom test car, the Alembic II, as well as a 4000-gallon milk tank truck. Boats of several types and a 17.5-foot tail as­sembly for a Navy bomber were among some of the other large items in the ex­

hibit. Smaller items included structural panels, boxes, trays, and other con­tainers, luggage, furniture, shock hel­mets, electrical parts, highway signs, lampshades, and components for air­craft, trucks, boats, and appliances.

Nuclear Energy Direct to Electric "Atomic Battery" holds promise for utilization of

reactor wastes —experimental model uses strontium-90

TT^IRECT conversion of atomic energy •*^to electrical gnergy is the accom­plishment of a new "atomic battery" developed by Radio Corp. of America. The unit has been used to run a tran­sistor audio oscillator circuit and pro­duce a tone audible 20 feet away. Cur-

Model of two basic elements of experi­mental RCA atomic battery shows cylinder with thin coating of radioactive material on its face being placed next to transistor­like wafer

rent experimental model provides a millionth of a watt, although a number of the cells could be stacked in a single case to produce a larger output.

Battery consists of a radioactive source coupled to a wafer of semicon­ducting crystal. An impurity is alloyed into the crystal to form a junction simi­lar electrically to those used in a junc­tion transistor, but considerably larger.

In the experimental model the radio­active source is strontium-90, one of the most abundant waste materials from the fission of uranium in a reactor. Stron­tium-90, a highly active source of beta particles, has a half-life of roughly 20 years. Both germanium and silicon have been used as the semiconductor, and antimony is the impurity material.

In the battery, 0.003 cc. of radioac­tive strontium is spread in a thin layer against the junction wafer. The layer of strontium bombards the semicon­ducting crystal with several billion elec­trons per second. As the electrons pene­trate the wafer they release an average of 200,000 slower electrons each.

When connected to the transistor oscillator circuit, the battery's 0.2 v.

potential provides a current of 5 ma. Best efficiency of energy conversion so far obtained exceeds 1%. A large part of the original energy is lost as heat in the crystal wafer. With the refinement of present techniques, an efficiency of 10% appears to be a reasonable goal.

Radlooctive Source Silicon

Antimony

TypicaJ Generator Unit

Radiated electrons bombard wafer and re­lease many more electrons which provide battery's current and voltage. Drawing shows a typical arrangement for such a battery

Greater power can be obtained by in­creasing the present 50 millicuries.

Pure strontium-90 emits only beta rays, with no harmful gamma radiation. Crystal structure of many substances is gradually damaged by electron bom­bardment, a factor that has yet to be accurately determined in this case.

Prospects for providing considerable quantities of electrical power from large accumulations of otherwise wasted radioactive material are claimed to be excellent. Such atomic batteries will b e highly compatible with future equip­ment using transistors, since both have the advantages of compactness, rugged-ness, and long life.

Somewhat less enthusiasm has been shown in some other quarters. An esti­mate that it would cost $20 million to operate a refrigerator with atomic bat­teries was made by Fischer Black, edi­tor of Electrical World, in a talk before the New York Society of Security An­alysts. H e also stated that a quantity of such batteries sufficient to operate an automobile might be in the neighbor­hood of 200,000 pounds in weight.

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