NASA Contractor Report 189101

High Temperature Strain GageTechnology for Hypersonic AircraftDevelopment Applications

W. L. Anderson and H. P. Grant

United Technologies Corporation

Pratt & WhitneyCommercial Engine BusinessEast Hartford, Conn. 06108

February 1992

Prepared forLewis Research CenterUnder Contract NAS3-25410

National Aea'onauties andSpace Administration

(NASA-CR-189101)

GAGE TECHNOLOGY

DEVELOPMENT

HIGH TEMPERATURE STRAIN

FOR HYPERSONIC AIRCRAFT

APPLICATIONS (PWA) 56 pCSCL 16B

G3135

N92-22239 _;

Unclas

0083767

FOREWORD

This report presents the results of an experimental evaluation of two types of

wire strain gages each on two types of substrate materials applicable to

hypersonic aircraft development. The evaluation was conducted under the "High

Temperature Strain Gage for Hypersonic Aircraft Development Application"

program under Contract NAS3-25410.

The original Pratt & Whitney Program Manager was Howard P. Grant who retired

in September 1989. He was replaced by Mr. Wilbur L. Anderson who served as

Program Manager for the remainder of the program. Acknowledgements are given

to Mr. Richard G. Claing and Mr. Armand 3. Latraverse who were involved in the

test preparation and strain gage installation, respectively.

ii

PRECEDING PAGE BLANK NOT FILMED

TABLE OF CONTENTS

Section

i. 0 SUMMARY

2.0 INTRODUCTION

3.0 EXPERIMENTAL DESIGN AND TEST PLAN FORMULATION

Test Equipment

Test Specimen DesignInstrumentation of Test Bars

Test Procedure

Apparent Strain Testing

Drift Testing

Gage Factor Testing

Creep Testing

Test Circuitry

4.0 TEST PERFORMANCE AND ANALYSIS OF RESULTS

Palladium Chromium Gages

Apparent Strain Data (PdCr)

Drift Data (PdCr)

Gage Factor Data (PdCr)

Creep Data (PdCr)

BCL-3 Gages

Apparent Strain Data (BCL-3)

Drift Data (BCL-3)

Gage Factor Data (BCL-3)

Creep Data (BCL-3)

Comparison of Results

Comparison of PdCr to BCL-3 on IN100

Comparison of PdCr to BCL-3 on CuZr

Comparison of IN100 to CuZr for PdCr

Comparison of IN100 to CuZr for BCL-3Insulation Resistance Data

Thermo-electricity Data

Post-test Inspection

5.0 CONCLUSIONS

PdCr Gages

BCL-3 GagesGeneral

6.0 REFERENCES

APPENDIX

Report Documentation Page

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SECTION 1.0

SUMMARY

A program was conducted to evaluate two types of wire strain gages each on two

types of substrate materials applicable to hypersonic aircraft development.

The program was conducted under Contract NAS3-25410, "High Temperature Strain

Gage for Hypersonic Aircraft Development Applicatlons" with the objective of

establishing the extent to which the temperature llmltatlon of 700K (801°F)

can be overcome by employing two advanced gage alloys: a new palladlum-13_

chromium alloy and a basellne Iron-chromlum-alumlnum alloy. The specific

objective was to establish the durability and accuracy of wire strain gage

systems under simulated hypersonic aircraft operating conditions.

Two alloy wire strain gages, Pd 13_ Cr (by weight) and BCL-3, on IN100 and

Cu .15_ Zr alloy substrates were evaluated. The PdCr and BCL-3 strain gages

were designed by Pratt & Whitney and Battelle-Columbus Labs, respectively, and

installed on test bars. The gages were connected to Wheatstone bridge circuits

and the outputs were recorded on a microcomputer based acquisition system.

Four types of testing were conducted on the strain gages:

i. Apparent strain testing: zero shift with temperature.

2. Drift testing: zero shift with time, without strain.

3. Gage factor testing: strain sensitivity.

4. Creep testing: zero shift with time, with strain.

Results of the testing have shown the strain gages to have good resistance

stability as summarized below:

o PdCr gages have good resistance stability below 866K (1100"F), the Pt

temperature compensation element is effective and the drift rate is

reduced by a NiCrA1 coating.

o BCL-3 gages have good resistance stability above 800K (981"F) but the

drift is high at 700K (800°F).

Insulation resistance is less then one megohm above 900K (II61@F) and

the thermo-electrlc effects of both gage types are low with the lead

configurations tested.

SECTION2.0INTRODUCTION

The objective of this work is to establlsh a technology base for use of high-

temperature wire-form static strain gages on materials applicable to hypersonic

aircraft development at temperatures above 800K (981°F).

A goal in the field of aeronautical research is the development of hypersonic

aircraft capable of flying take-off to orbit or transporting people to the far

Pacific basin in a few hours. Because of the high speeds involved, such

aircraft will have structures that are subject to high temperatures (more than

800K) and very high heat fluxes. In the development of such aircraft, there

will be a need for hlgh-temperature static strain measurement which is beyond

the state-of-the-art strain gage technology. This work is intended to

contribute to the technology of hlgh-temperature static strain measurement on

materlals and under conditions that are pertinent to hypersonic aircraft

development needs.

The strain gage alloys which have the highest potential for static strain

measurements at temperatures above 800K are those of the FeCrA1 family and

those of newly developed PdCr. The FeCrAI alloys have a relatlvely low but

nonlinear electrlcal-reslstance-versus-temperature character and good

oxidation resistance. The FeCrA1 alloy selected for this work is BCL-3,

developed under NASA sponsorship at Battelle-Columbus Labs (Ref. i). The PdCr

alloy has a falrly llnear electrlcal-reslstance-versus-temperature character,

but a temperature-coefflcient-of-reslstance high enough that a thermal

compensation scheme is needed. It also has fair oxidation resistance. The PdCr

alloy selected for this work is 87_ Pd and 13_ Cr (by weight), developed under

NASA sponsorship by the United Technologles Research Center (Ref. 2).

Because of the high temperature and very high heat flux expected in the

hypersonic aircraft structure, the structure must be fabricated of an uncooled

hlgh-temperature material or a cooled low-temperature material. If a cooled

material is used, the thermal conductivity should be high. The high temperature

material selected for this work is IN100 ( 59_ Ni, 15_ Co, 9.5_ Cr, 5.5_ AI,

4.8 Ti, 3_ Mo, i_ Fe, I_ V and 1.2Z other) and the low temperature material

99.85_ Cu and .15_ Zr.

SECTION3.0EXPERIMENTAL DESIGN AND TEST PLAN FORMULATION

Test specimens were designed for use with existing test fixtures and for the

four types of tests listed below to be conducted on the strain gages:

i. Apparent strain testing: zero shift with temperature.

2. Drift testing: zero shift with time, without strain.

3. Gage factor testing: strain sensitivity.

4. Creep testing: zero shift with time, with strain.

TEST EQUIPMENT

Existing strain gage test equipment, shown in Figure I, was used for all four

types of tests. It includes the bar bending mechanism, a 25.4 cm (10") long

tube furnace, a temperature indicator, an oven temperature control, a bridge

connection box and a Hewlett-Packard data acquisition system. The test bar

bending mechanism, shown in Figure 2, consists of a vise to hold the clamping

fixture and a stepping motor driven deflection device. The clamping fixture,

with a test bar (old design) installed, is shown in Figure 3.

TEST SPECIMEN DESIGN

Test bars 20.3 cm (8") long, 3.5 cm (1-3/8") wide and .64 cm (1/4") thick were

fabricated as shown in Figure 4. Only bars intended for gage factor and creep

testing were fabricated with the tapered section, the others being rectangular.

The purpose of the taper is to provide constant strain over the active length.

The PdCr strain gages were designed by Pratt & Whitney as shown in Figure 5.

The large grid size, .76 cm (.3") square, is needed to obtain a high enough

gage resistance (about 58 Ohms) for good measurement with the large wire

diameter (and low resistance). Pt was selected for the thermal compensationelement because of the stable resistance characteristics and high temperature

coefficient of resistance. The 3.3 Ohm resistance is designed to provide the

right amount of compensation in a 1:1 bridge. The .16 mm (6.3 mil) diameter Ni20_ Cr leadwires are larger than desirable, but necessary to keep the

resistance low relative to that of the gage grid. Lead resistance is about 4.6

ohms.

The BCL-3 strain gages were designed by Battelle-Columbus Labs as shown in

Figure 6. The grid size is standard for this 120 Ohm gage. The FeCrAI ribbon

(Hoskins alloy 875) lead is a standard used by Battelle. Lead resistance is

about 2.9 ohms.

Installation of the gages and thermocouples on the test bars is shown in

Figure 7. The gage leads are about 6.35 cm (2.5") long, being spliced to Ni

Clad Cu wire about 2.54 cm (1.0") from the end of the bar. The splice is

brazed with Nicrobraz 150 (from Wall Colmonoy Corp.). The prep coat of NiCrA1

(Metco 443), precoat and overcoat cover the shaded areas. The thermocouples

are made of .2 mm (8 mil) diameter, type K wire, with the Junction welded

prior to installation on the precoat. A non-precoated area was left on side 1

for the installation of a reference strain gage (WK-06-062AP-350 from

Measurements Group) prior to the gage factor tests. The types of bars gages,

precoats and overcoats are as follows:

3

ORIGTNAL PAGE

BLACK AND WHITE PHOTOGRAPH

Figure i.- Strain Gage Test Equipment

O0

Figure 2.- Test Bar Bending Mechanism

4

ORYGINAL PA('_E

BLACK AND WHITE PHOTOGRAPH

Figure 3.- Test Bar Clamp Fixture

1.385"/-L1.365"

8.000"7.980" 3.010"

2.990"

2.510"- I- 2.490"

.257"!

-- I

/2'_ k-"152o"/ .500"

.375"

iT'

.258"

.254"

JI

I I

SURFACE FINISH 15 MICRO-INCH A-ABOTH SIDES IN TAPERED SECTION

ALL EDGES TO HAVE .030" RBREAK OVER CENTER 4" OR MORE

Figure 4.- Strain Gage Test Bar

!

0.30-_0"

±

0.300'L-.----_-

P

GRID: 0.00176 INCH DIA. WIRE

_: 58 OHMS

_J_E_=_: 0.001 INCH DIA.PLATINUM WIRE

_: 3.5 OHMS

_: 0.0063 INCH DIANi 20Cr WIRE

LEAD ATTACHMENT: PARALLELGAP WELD

FABRICATED AT PRATT & WHITNEY

LEAD A LEAD B LEAD C

Figure 5.- Palladium 13Z Chromium Dual Element Strain Gage

m

Figure 6.- FeCrAI (BCL'3)

! GRID: 0.00167 INCH DIA. WIRE

_: 122 OHMS

_: 0.032 INCH X 0.002 INCHHOSKINS ALLOY 875 RIBBON

LEAD ATI'ACHMENT: TACK WELD SANDWICH

FABRICATED AT BATTELLE

Strain Gage

6

REFERENCE GAGENICLAD C.,u, 15 MIL WK-06-062AD-350

GAGE #1 _ DIA. WIRE, RED VARGLASS WITH EPOXYrJ_ / SLEEVING FROM EDGE INSTALL AFTER

/ OF BAR (STRIP SGW-7) THERMAL TEST_AJ/ -- BRAZE SPLICE WITH

\\\ / / WITH ROKIDE /// _, #1

\\\ / A2s" / HTOVERCOAT i ///U_ /

\\t / 10 ="'- :o:o:o-o-_%°_-o-o-o...... °.... °_ .... oo ° o : oO;,o;,op:o:o:o .__.

o oZo_o-_o__ p_o_o;,o;.oz_o.©c _b°^------

I - - ITESTGA_,_s_J_ ,. [I "/ Iwn_COA,- -T-- ,.ERMOCO;_-LE=_PE=,--I

GROUND WIRE _m,; ,_ I '' _ IM/_BARE WIRE COVERED WITH RED V]RGLASS

RES. WELDED TO BA_I_ SIDE 2 '_"

W,=I ..........L-.-

_[ 2 4!5 L ROKIDE HT PRECOAT THERMOCOUPLE LEADS WITH ROKIDE HT OVERCOAT(_ GAGE # " " MErCO 443 PREP. COAT "

(SHADED AREAS)

Figure 7.- Test Bar With Strain Gage And Thermocouple Installation

Bar Gage Bar

Numbers Material Material Precoat Overcoat

01 02 03 04 PdCr IN100 Rokide Rokide

05 PdCr IN100 Roklde Roklde & NICrAI

06 26 PdCr IN100 AI2031Zr02 AI203/Zr02

18 PdCr IN100 Roklde AI203/Zr02

25 PdCr IN100 AI203/Zr02 AI203/Zr02 & NICrAI07 08 09 10 ii 12 PdCr CuZr Rokide Rokide

13 14 15 16 17 BCL-3 IN100 Rokide Rokide

19 20 21 22 23 24 BCL-3 CuZr Rokide Rokide

The AI203/ZrO 2 is a mixture of 96% alumina and 4% zirconla powder flamespray coating intended to provide improved oxidation protection to the PdCr

gages. The NiCrA1 (Metco 443) coating is the same as that of the prep coat and

is also intended to provide oxidation protection.

INSTRUMENTATION OF TEST BARS

The PdCr gages were fabricated by Pratt & Whitney using gage wire provided by

NASA. The BCL-3 gages, with the FeCrA1 ribbon leads attached, were purchasedfrom Batelle-Columbus Labs. All gages were Installed in the Pratt & Whitney

Strain Gage Lab, except for PdCr gages with alumlna/zlrconla overcoat which

were installed by HITEC Products, Inc. The two bars with NICrA1 oxidation-

resistant coating were overcoated at Pratt & Whitney.

TEST PROCEDURE

Apparent strain, drift, gage factor and creep testing were conducted as

described below. At every test point, the strain gage bridge output for eachgage (with both positive and negative excitation) was recorded along with the

two thermocouples, insulatlon resistance and time. Oven temperature, excitation(Sv dc) polarlty and precise bar deflectlon were controlled by the data

acquisition system. The excitation was applied to each gage circuit only when

a measurement was to be made (not continuously).

Avvarent Strain Tes_in_

Data were recorded during at least three heating and cooling cycles on all of

the gages. The first cycle was the heat-treatlng cycle and the heat-treatlng

temperature was higher than that of the other cycles by 22K (40°F) for PdCr

and 28K (50°F) for BCL-3 gages. The heat-treating period was 30 minutes. Data

were recorded at equal time intervals during the temperature cycles.

Drift Testing

Data were recorded during constant temperature periods of i0 hours. Testing at

three different temperatures (five for BCL-3 on IN100) was conducted. Each

drift test was preceded by a heating cycle to the maximum temperature (for

each gage/bar type) and a cooling cycle to the drift temperature. Data were

recorded at equal time intervals during the drift and temperature cycles.

Gage Factor Testing

Data were recorded at room temperature, four intermediate temperatures andmaximum temperature for each gage/bar type. Stabilization time was 30 minutes

at each temperature. The temperature sequence was room, first, second, third,fourth, maximum, fourth, third, second, first, room, maximum, fourth, third,

second, first and room. At each temperature, measurements were made in both

compression and tension using a 0, +, 0, -, 0, +, 0, -, 0 bar deflectlon

sequence (nine readings per sequence producing four compression and four

tension measurements. The deflection sequence was run at both approximately500 and 1000 mlcro-straln. The exact strain level for each deflection was

measured at room temperature using reference (commerclal) foll gages.

8

Creep Tes.tinR

Data were recorded during constant temperature periods of i0 hours, duringwhich a strain level of I000 micro-strain was applied (gage I in tension and

gage 2 in compression). Testing at three different temperatures was conducted.

Each creep test was preceded by a heating cycle to the maximum temperature

(for each gage/bar type) and a cooling cycle to the creep temperature. The

strain was applied at the beginning of the cooling cycle. Data were recorded

at equal time intervals during the creep and temperature cycles.

TEST CIRCUITRY

All gages were connected to a Wheatstone bridge circuit as shown in Figure 8.

The BCL-3 gages required setting R2 = RG for a i:i bridge (because they

have no RC). The temperature compensated PdCr gages required setting

R2+Rc= RG (R2 being approximately 55 Ohms) for a i:i bridge. Use ofother than a i:i bridge ratio results in a more complex bridge sensitivity

factor, as shown in Figure 9, and in lead-reslstance changes not canceling inthe two bridge arms.

- EI

IRt/_ R2

_,_. °Eo°

R3 "_*/

RL

tVt4_R G (Pt)RL (PdCr)

RL

GAGE DESIGNED FOR 1:1 BRIDGE (R 2+R L+R C=R L+R G)

Figure 8.- Bridge Circuit - Temperature Compensation

___, // R8 =R2* RC

FOR A 1:1BPJDGE: RB =I

%

AEo" EI _4_÷_.__

Figure 9.- Bridge Formula

Insulation resistance was measured using the Ohmmeter-type circuit shown in

Figure i0. The gage was switched out of the bridge circuit during this

measurement (switches are not shown in Figure 8). Measurements were made

between each of the two gage leads (in the case of PdCr, leads B and C inFigure 5), and the ground wire attached to the test bar. For each lead, two

measurements were made: one with plus and one with minus polarity (of the 1.5

volt dc supply) and the two averaged.

10 OHMS

RI = _--_ (10)-10 OHMS

Figure i0.- Insulation Resistance Measurement Circuit

l0

SECTION 4.0

TEST PERFORMANCE AND ANALYSIS OF RESULTS

Planned and revised maximum test temperatures are shown below. Maximum

temperature for the PdCr alloy was revised after excessive drift was measured

at II50K and above.

Bar Original Revised

PdCr IN100 1144K (1600°F)

PdCr CuZr 811K (1000°F)

BCL-3 IN100 1144K (1600"F)

BCL-3 CuZr 811K (1000°F)

866K (II00°F)

Apparent strain, drift, gage factor and creep testing were conducted and the

test data were recorded on a Hewlett-Packard microcomputer based data

acquisition system. Data files, containing voltmeter readings, were converted

to ASCII format and transferred to IBM MS-DOS files for import into Lotus 123

(worksheet software). Conversion to engineering units and plotting were done

using Lotus 123. In most cases, the thermal cycles were identified on the

plots by the cycle number and A for heating, B for cooling, HT for heat treat,

DR for drift and CR for creep.

PALLADIUM CHROMIUM GAGES

Maximum test temperatures for each test is shown in Table I.

Avvarent Strain D_a (PdCr)

Apparent strain data for PdCr gages on IN100 bars are shown in Figures Ii and

12. The first tests were conducted on bars 03, 01, 02 and 04 (Figure Ii) to

determine the time and temperature effect on apparent strain. From these

results, the maximum test temperature for PdCr gages was reduced to 866K

(II00"F) from the orlglnally planned I144K (1600"F). Bars 05, 06, 18 and 26

(Figure 12) were then tested within the revised maximum temperature.

Bar 03 (gage 03-1 only) was subjected to 14 temperature cycles to 894K

(1150°F) before and temperature cycles to 873K (III2°F) after a 50-hour soak

at 873K. Before the soak, there was a steady increase in the slope with each

cycle (2 of the 6 plotted). The 50-hour soak resulted in greater resistance

stability but with great loss of temperature compensation. Most data for bar

03 were acquired with a hand-balance strain indicator because the data system

was not ready for use when testing started. Gage 03-2 is not shown because the

analysis was not fully completed, but enough points were analyzed to show that

the trend was the same.

Bar 01 was subjected to one thermal cycle to i023K (1382°F), with a one hour

dwell at I023K and three cycles (only two shown) to 873K (1112°F). The initial

heating cycle is not shown because of a data system malfunction. The dwell at

1023K resulted in good resistance stability but with a large loss of

temperature compensation.

11

TABLE I.- PdCr STRAIN GAGES: TESTS CONDUCTED AND MAXIMUM TEMPERATURES (K)

Bar Bar Heat Apparent Drift Gage Creep

Number Material Treat Strain Factor

01 IN100 1022 853

02 IN100 1023 853 1023

03 IN100 894 894 894 866

04 IN100 894 866 866

05 N IN100 889 866 700

811

06 AZ IN100 889 866

18 R IN100 889 866 700

811

25 R,N IN100 Not Tested

26 AZ IN100 889 866 700811

07 CuZr 822 811

08 CuZr 822 811 700

755

811

09 CuZr 833 811

10 CuZr 833 811

11 CuZr 833 811

12 CuZr 833 811

866

866

811

811

811

297

700

755

866

700

755

811

AZ: Alumlna/Zirconla Precoat and OvercoatR: Roklde Precoat and Alumlna/Zirconla 0vercaot

N: NICrA1 Overcoat

12

70

50

\

!_ ,o--

cv

20

10

PdCr Gage 01-1 Cycles 1B,3A,3B,4A,4BAppowen_ gtmle Ju189 (01_ALL1)

/

/

/0.2 0.4 0.6 0.8 I

Te mpem_ee (K)

+ 1B O _A Z_ 3B X 4A _ 4B

PdCr Gage 01-2 Cycles 1B,3A,3B,4A,4BAppane_ S_m;n JuI89 (01 ALL2)

80

7O

6o

E so--O^

,°c v 30

20v

I0

//

/.:. _ r i

f0

o.2 0.4 o.6 0,8 1(_ousond_)

Temperature (1<)

"t 1B 0 5A Z_ 3B X 4A _ 4B

PdCr Gage 02-1 Cycles 1A,1B,2A,2B,3A,SBAppor_nt Stroin AugB9 (02_All 1}

100!

gO

BO

T70

E

_g___ soEo

_, 3o

2O

10

_P

0.2 0.4 0.6 0.8 1

(_ouso_d=)

Temperoture (K)

[] I A + 1B O 2A & 2B x _ V 3B

PdCr Gage 03-1 Effect of 50 Hrs at 873K

50

E" -50

_ -- 100

.-__ -15o

U_ -200=:

v

-300

-35O

J_

/

40O 600 800

Temperotu_ (K)

r_ Cy{ 1-14 (Before) -_ Cyc 19 & 20 (After)

PdCr Gage 02-2 Cycles 1A, IB,2A,2B,3A,3B_op¢,,-_ S_--;_ ,t, g89 (02_*U.2)

120

110

100

_ go

3O

10

-10=-- 1

0.2 0.4 0.6 0.8 1(T_ouso_ds)

Temperoture (K)

O 1A + I B 0 _J_ _. 2B X 3A _ _B

Figure Ii.- Apparent Strain of PdCr

Strain Gages on IN100 Bars

13

PdCr Gage 04-2 Cycles 1A,1B,2A,2B,3A,3B_por_nt Stm;n Jul 89 (04__L2)

30_

25

"E 2O

8

E lS

r= J

e___ _o!Eo

5E

o

-5

2O0

[] 1A

--10

J

400 600

Tempemtur© (K}

+ 1B O 2A _, 21B ;X 3A V 3B

J

_3 1A

40O 6OO 800

Tempem_re (K)

+ IB 0 2A & 2El X 3_ V 3El

Figure ii.- Continued

14

"E lO

5

un o

\ -5£.

-10£

-15

-20

9

8

7

5

?_ 5r

r 4I=

3

1

0

_ s

F o

I ,o

e_u M -5

_- -10

_ -15v

PdCr Gage 05-1 Cycles 1A/HT/B,2A/B,3A/B&Ol_r_t $tr_;n Jan 90 (05_ALL1)

2O

--2O

--25

j_a'e--_ s-ee-._ a...se_

200 400 E00 800

Tempem_.ure (K)

D IA & IHT + IB O 2A & 2B X 3A V 3B

PdCr Gage 05-2 Cycles IA/HT/B,2A,/B,3A/BAppamrrt Struin Jan gO (05_ALL2)

2O

15

10

5

-5

-10

-15

-20

Tempe mtur_ (K)

r'l 1A & 1t41" + 1B O 2A ,e, 28 x 3A 'e 3B

PdCr Gage 05-2 Cycles 2 & 3Aipparen_ Straln (05_ALT2)

PdCr Gage 06-2 Cycle 1A,1B,2A,2B,3A, SB_por_<t S_oT. _pr go (O6_ALI_)

20

15

10

5

i °-5

-10

-15

-20

PdCr Gage 18-1 Cycle 1A,1B,2A,2B,3A,3BA_or_nt 51tro;n Mar 90 (18_ALL1)

_ _._a.._ _

200 400 600 _00

Tem_ n:rt,ur= (K)

25

20

15

10

-- 0

-5

-10

-15

13 1A + IB 0 2A & 28 X 3A _' 3B

+

20o

t3 IA

40O 600 8OO

Temp=rotur_ (K)

4- 1B O 2A A 2IB X 3_k V 3B

PdCr Gage 18-2 Cycle 1A,1B,2A,2B,3A,3BA_amn_. Strain M=r 90 (18 AL_}

"= _s-..e__;_e...s-

200

Jr

400 600 800

Temperature (K)

O IA + 1_ O 2A & 2B X 3A V 38

Figure 12.- Apparent Strain of PdCr Strain GaEes on INI00 Bars with Oxldatlon

Preventive Overcoat

15

25

20

e_Eo

_ o

PdCr Gage 26-1 Cycle 1A,1B,2A,2B,SA,3BApporen'[ 5t.,"oln Apr 90 (26_ALL1)

--10

--15200

[] IA

8O0 8o0

"le mpe_,"e (K)

_- 1B 0 2A _ 28 X 3A V 38

Figure 12.- Continued

Bar 02 was subjected to one cycle to 1023K (1382°F), with a 16 hour dwell at

1023K, and three cycles to 873K (1112"F). The increased exposure time was

intended to further improve resistance stability, but resulted In a greater

loss of temperature compensation.

Bar 04 was subjected to one cycle to 893K (1148°F), with a one hour dwell and

two cycles to 866K (1100"F). The temperature compensation was much better, but

there was stlll a significant increase in slope on each cycle. The maximum

test temperatures of 886K (II40°F) for the heat treat cycle and 866K (II00"F)

for the apparent strain cycles were established for the other gages/bars of

this type. The heat treat duration was established at 30 minutes.

Bars 05, 06, 18 and 26 incorporated two oxidation resistant schemes as

described In the "Test Specimen Design" of Section 3.0. The apparent strain

results for these bars are shown In Figure 12. On bar 05, a coating of NiCrAl

flame spray was applled over the Rokide overcoat as an oxygen barrier. The

increase in slope on cycles 2 and 3 was slightly less than shown on bar 04

(standard overcoat and same temperature cycles). A typical time vs temperature

plot Is also shown for two cycles of bar 05. Bar 06 was instrumented wlth a

precoat and overcoat of aluminalzlrconia for oxidation resistance (same as bar

26). The increase In slope on cycles 2 and 3 was slightly less than shown on

bar 04 (standard overcoat and same temperature cycles). Because gage 06-1 had

an open circuit after Installation, no data were acquired. Bar 18 was instru-

mented wlth a standard Roklde precoat and an alumina/zirconla overcoat for

oxidation resistance. The Roklde precoat was used because of extreme difflculty

In installing the alumlna/zlrconla precoats on bars 06 and 26. Although the two

gages were identical, gage 18-1 experienced a much greater increase in slope,

on cycles 2 and 3, than gage 18-2. Thls difference has not been explalned. Bar

26 was instrumented wlth a precoat and overcoat of alumina/zirconla for oxida-

tion resistance (same as bar 06). The increase in slope on cycles 2 and 3 was

sllghtly less than shown on bar 04 (standard overcoat and same temperature

cycles).

16

Apparent strain data for PdCr gages on CuZr bars are shown in Figure 13. Bars

07, 08, 09, 10, ii and 12 were all instrumented with the standard Roklde

precoat and overcoat and were subjected to a heat treat cycle to approxlmately833K (1040°F) and two apparent strain cycles to approximately 811K (1000°F).

The heat-treat period was 30 minutes. The exact maximum test temperatures for

each bar are shown in Table I. For bar 07, data from all three cycles for both

gages were lost because of a data system malfunction. Three additional cycles

(4, 5 and 6) were run and data for gage 07-2 are shown. The change in slopewas small, but this stability may be due to the additional cycles run.

However, data from gage 07-i was not properly recorded. For bar 08, data for

cycles 2, 3 and 4 are shown. Data from cycle i were lost because of a recorder

malfunctlon. Cycles 3 and 4 were run after making a slight adjustment of the

temperature compensation circuit to increase the compensation (reduce R2).

On cycle 2, R2 was Inadvertantly set too high (70.1 and 65.8 ohms for gagesi and 2, respectively). Prior to cycles 3 and 4, R 2 was set to the proper

value such that R2+R C = RG (54.2 and 53.3 ohms, respectlvely). Theresults show that the 3.3 ohm compensator is about the correct value for the

58 ohm gage (RG/R C = 17.6). Bar 09 had the lowest (negative) slope of allthe PdCr gages. The increase in slope on cycles 2 and 3 was similar to the

other gages, however. The data from bar I0 shows a premature temperature drop

and recovery on cycle 3A. This additional time at temperature may account for

the slope on cycle 3B being greater than that of the other cycles. On bar ii,

the data of cycle IB were lost because of a data system malfunction. The heat

treat dwell (30 minutes) is plotted so that the end points of cycle IB may be

determined. Bar 12 had near optimum thermal compensation (nearly zero slope).

This happened by chance because the resistances of the gage and compensation

grids cannot be controlled any better than they were in this program.

17

PdCr Gage 08-1 Cycles 2A,2B,3A,3B,4A,4BApparent $'L'11ln 0d¢,_9 (08 ALL1)

16 =

_ ,o

;E

g .2

0

-2

2

o

E -2

E o -6

o:

_e -10

-12

-14

[] 2A

-16

6oo Boo

Tempemtur'= (K)

+ 2B O 3A _ 3E¢ X 4A V 4B

PdCr Gage 09-1 Cycles 1A,1B,2A,2B,3A,3B_ar=nt _-Q;n Dec 8g (09__.1)

6

_=[

20O

O 1A

PdCr Gage 07-2 Cycles 4A,4B,SA,5B,6A,6BAppe,-=_l Strein No_B9 (07J_.A)

ao!

i

!

is

_,oEo 8

;g

_ 4g

-2

r,

Tempenature (K)

[] 4_, + 4B O 5A & 58 X 6A V 68

PdCr Gage 08-2 Cycles 2A,2B,3A,3B,4A,4B• pl_r_t Sb'_in O¢t89 (08 AI-I_)

20

1B

16

14

12

i,o

4

2

0

-2

6

4

2

0

2

4

6

8

0

2

4

62O0

O 1A

w

Y

200 4_3 600 800

Tempem_ne (K)

0 2A + 2B O 3A z_ 3B X 4A V 48

PdCr Gage 09-2 Cycles 1A,1B,2A,2B,3A,3BApparent Stna;n Dec 89 (O9_ALL2)

\

4OO 500 8,OO 400 600 BOO

Tempena_re (K) Temperature (K)

•F" 1B 0 2A & 2B X 3A V 3El 'i" 1B 0 2A A 2B X 3A 1_ _'B

Figure 13.- Apparent Strain of PdCr Strain Gages on CuZr Bars

18

PdCr Gage 10-1 Cycles IA, IB,2A,2B,3A,3BAppore_. S'b'o;n Oc_ 89 (10. ALL1)

16

14

12

'%.

_ 8

I 'o2g s

\ 2

0

-2

-4

I

-6

40O 6O0 800

Temperature (K)

O tA + 1B O 2A & 2B × 3A V 3B

PdCr Gage 11-1 Cycle IA, 1HT,2A,2B,SA,3BAppor_nt Sb_;n May 90 (tl ALL1)

10

6

6 4

+i ou

$

-8

-lO

-122oo 400 600 8OO

Temperoture (K)

g 'IA + IHT O 2A 4 2B X ,SA V 3B

2

8 o

E -2

e _ -4ul, l

--10

-12

--14

-t6

PdCr Gage 12-1 Cycles 1A,1B,2A,2B,3A,3BAppor_"ff. S_;n Moy 90 (12 ALL1)

6

4

'\

D 1A

400 6OO 80O

+ IE O 2A & 2 ¢1 x 3A V

t0

8

6

4

2

-1

-E

£

PdCr Gage 10-2 Cycles 1A, IB,2A,2B,SA,SBApporent _ro;n Oct 89 (IO ALL_)

• 4 t

200

El 1A

4OO 500 8OO

Tempem_Jr_ (K)

+ 1B 0 2A 6 2B X 3A V 3B

PdCr Gage 11-2 Cycle 1A, 1HT,2A,2B,3A,3BApporent Stro;n M_y 90 (11__U-2)

I

200 4O0

1A "1" 1HT

6O0 BOO

T=mpemiure (K)

o 2A & 2B x 3A _ 3B

I

PdCr Gage 12-2 Cycles 1A,1B,2A,2B,SA,3BAppont_t Stlr_in May 90 (12 ALL2)

6

4

2

0

.2

.4

"6

IC --

1|

2OO 4OO 6OO BOO

Te rope mtur_ (K)

1A + 1B O 2A & 2B X _ _ 36

Figure 13.- Continued

19

Drift Data (PdCr)

Drift data for PdCr gages are shown in Figure 14. In each plot, data shown for

approximately the first hour represent the period of cooling from the maximum

temperature to the drift temperature, and the next 10 hours (I through ii) isthe drift test period. Bar 08 was instrumented with the standard Rokide

precoat and overcoat. Bar 05 was instrumented the same as Bar 08 but with the

addition of a coating of flame sprayed NiCrAI. No data were acquired from gage

05-2 at 700K because of a data system malfunction. Bar 18 was instrumented

with a Roklde precoat and alumina/zlrconia overcoat. Bar 26 was instrumented

with both precoat and overcoat of alumina/zlrconia.

The following is a summary of the drift rates (in micro-0hms/0hm per hour).

Bar-Gage Precoat Overcoat 700K 755K 811K

(800°F) (900°F) (1000°F)

08-1 CuZr Rokide Rokide +i00 +100 +600

08-2 CuZr Rokide Rokide +100 +100 +600

05-1 IN100 Rokide Rokide/NiCrA1 +50 - -100

05-2 IN100 Rokide Rokide/NiCrA1 - - -100

18-1 IN100 Roklde A1203/Zr02 +50 - -600

18-2 INIO0 Roklde A1203/Zr02 +50 - +400

26-1 IN100 AI203/Zr02 AI203/Zr02 +I00 - +550

Gage Factor D_ta (PdCr)

Gage factor data for PdCr gages on INI00 bars are shown in Figures 15 and 16

and on CuZr bars in Figure 17. For each gage, the gage factor and gage factor

variation are shown. Each point on the gage factor plot is the mean of the fourmeasurements described in the "Test Procedure" of Section 3.0. The variation

is defined as two times the standard deviation of those four measurements as a

percent of the mean.

Strain levels, measured at room temperature with reference gages, were

repeated at elevated temperature with precise control of bar deflection and

while maintaining uniform temperature over the active bar length of 7.62 cm

(3"). Bar deflection is 5.94 mm (.234 inches) for i000 micro-straln and is

repeatable within ± 13 _m (.5 mil). Bar temperature was held constant within a

17K (30°F) range as determined from a temperature test on a similar bar

several years ago and shown in Figure 18.

The measured gage factor of 1.4 for the Pt compensated PdCr gage was about as

expected from published gage factors of 1.8 for Pd Cr and 4.8 for Pt. A

compensation element with a lower (than Pt) gage factor would desensitize the

PdCr less, but the resistance stability of Pt was worth the sensitivityreduction.

20

+.

£

12

11

_0

9

B

7

6

5

4

3

2

I

0

PdCr Gage 05-1 Cycles 4DR & 5DRDr_t Jan 90 (05 DRT1)

¥

I0 2 4 6 8 10

"_ne (h_)

+. 4DR (700K) X SOR (810l<)

PdCr Gage 08-1 Cycles 5DR, 7DR, 8DROHR. Oct 89 (08_DR1T)

13

8

8_" loT "O

e_

//

3

0

--=-

PdCr Gage 05-2 Cycle 5DRD,"_t Jo_ 90 (05_Din'2)

I0 2 4 6 8

l_me (houm)

× 5OR (810K)

I0

/

I 'o

u

J

i

_ eeet ,_Be_ Hml_'a"

_ --+,-+-I "+-_P_'_! _-_'¢"_ _"

2 4 6

Time (h c,_)

D 50R 700 K + 7OR 755 K

i'

IB 10 12

O 8OR 811 K

PdCr Gage 18-t Cycles 4DR & 5DRDrlf_ A_r go {18 C)RT1)

4 i

0

--2

-3

-4

-5

-5

0 2

_x

4 6 8

T,me (ho_)

10

4

12

PdCr Gage 08-2 Cycles 5DR, 7DR, 8DRDH_ O_t 89 (08 DR2T)

I

I IO

Jj+

_. _,-_u=_ B"_ _'1_

J

._i_ _ _

2 4 6 8 10

"n,,_,+ (hou_)

D 5DR 700 K + 7D_ 755 K O 8DR 811 K

PdCr Gage 18-2 Cycles 4DR & 5DRo,4_ A_- 9o 08_1:_T2)

_;;lim_4 -- --

_2

22 1____

21

20

16

14

_3

,,o0 2 4 6 8 10 12

+ 4om (_o0_<) x 5DR (B_K)

Figure 14.- Drift of PdCr Strain Gages

21

?6xE

11e_Eo

PdCr Gage 26-1 Cycles 4DR & 5DRDr'Tf_ Apt gO (26 DRT1)

23

22 _-

21

20lg _ _r'_" "+'+'_ _-_-_ "k_-t-t _-

17

_60 2 4 6 8 10 12

+ 4DR (TO0_) x 50_' (811K}

Figure 14.- Continued

22

2

1.9 --

1.8

1.7

1.6

g 1.s!

_ 1.4

1.3

1,1

1

2

1.9

1.8

1.7

1.6

_" 1.5

_ 1.4

1.2

1.1

1

2

1.9

1,8

1.7

1.6

1.5

g

1,2

1.1

1

&

0

o C 50O

PdCr Gage 03-1Goge !roctor (03__1)

A"r

o

A0

40O 6OO

TempemLure (K>

+ T 500 0 C 1000 _ T 1000

800

E

&

PdCr Gage 03-1_g= F'acto_ Voriot;on (03_OlrVl)

170

160 -- --

o150 -- &

140

,0

:0 0

0

_0

iO

bO

_Q0

_C

IC

_C

¢200 400

Tempe_4ur= (K)

O C 500 • T 500 0 C 1000 & T 1000

80O

;o

0

PdCr Gage 0.5-2Ooge Foctcw (03_gf2)

0

? $ O T

o oA 0 ¢ +

+ I

2OO

Temperc_Jre (K)

0 C 50(} ÷ T 500 O C 1000 _ T 1000

PdCr Gage 04-1Gage Foct_" (04_OF1)

8O0

2OO

:t +

[3

400 60O

Tempe_,'e (K)

[] C 500 _- T 5OO O C 10OO _ T 1000

I'80O

150

140

130

120

_10

100 --

90

7O

g 4o

2O

10 _

0

&

oo

7O

PdCr Gage 03-2Ooge ro_m.-VoHo_;m'_ (03 Gt'V2)

o+o

0

¢

8,0&

+

= -I+

^ o o ono

t = _oe

I4O0 500

Temperance (K)

0 C 500 + T 500 O C 10OO _ T 1000

PdCr Gage 04-1Oage F'ocbw Vo_o_.;o_ (04 GFV1)

8O0

50 ,, ,

40

+

• o 6

+ O+

o_ 20 Y" _ O

0 o& u+ _ ++

10 rl

" ' !8 "0

200 400 600 800

Tempe_ture (K)

O C 500 + T 500 o C 1000 _ T 1000

+

+

O

Figure 15.- Gage Factor and Varlatlon of PdCr Straln Gages on INIO0 Bars

23

2

1.9

1.8

1+7

.,_ 1.6

_ 1.5

g_ 1,4

1.3

1.2

1,1

1

PdCr Gage 04-2Goge Foct_- (04.G¢2)

0

"t"

400 600

Tempemturl_ (K)

Q C 500 t" T 500 O C 1000 -_ T 1000

8CO

7O

60

5O

_, 20

10

PdCr Gage 04-2Goge rocto_ Valor;on (04_GF'V2)

D O+

D

_. n a÷+

D

+ A _ O&

I. + 8 $+9

200 400 600

Tl_mpem_JPe (K_'

0 C 500 + T 500 0 C 1000 _, T 10,00

6

8CO

Figure 15.- Continued

24

PdCr Gage 05-1Oe?e Factor (05_CIF1)

2

1.9

1.8

1.7

1.6

_ 1.5 --

200 400 _00

Temperature (r)

[3 C 500 + T 500 O C 1000 A T 1000

1.4

1.3

1.2

1.1

1

O

2O0

PdCr Gage 05-1Goge Iroctor Vor{ot;on (05_GF'V1)

0

÷9+

%v D

.... 43

4O0 6OO 80O

Temperature (;')

D C SO0 + T 500 ¢ C 1000 _, T 1000

0 --

u

+

2

1.9

1.8

1.7

._ 1.5

¢- +.5

1.3

1.2

1.1

1

PdCr Gage 05-2Oege rat's:*- (05._0r2)

i I

2,

2:

2q

1,

1

g,

g

PdCr Gage 05-2Gage roc_or Vor{otTon (0S (_¢V2)

4_

++ ÷

o 0

A

o

t o = °|

200 400 600 800 200

Te n'_pe roture (1_

D C500 + TSO0 O C 1000 Z_ TIO00 D C500

400 54)O

Tempen3_ure (F)

+ T 500 O C 10OO A T 1000

2

1.9

1.8

1.7

g_ 1.4

1.2,

1.2

1+1

1

PdCr Gage 18-1Gage F'octo_" (18.0F1)

/

3:

3(

21

2(

2,

2:

2(

H

} +,

2OO

PdCr Gage 18-1Oage /oct, or VoHo_.ion (15 C,F_I)

200 400 500

Ternpemtu_ (K)

C 500 + T 500 O C IG_O A T 1000 13 C 500

÷

O E)

D

O 13

e

,0[3

e

4

o!+

Tempera_ture (K)

+ T 500 O C 1000 A T 1000

I

--+4A

°o

<>

800

Figure 16.- Gage Factor and Variation of PdCr Strain Gages on IN100 Bars with

Oxidation Protective Overcoat

25

2

1.9

1.8

1.7

1.6

1.5

1.4

1.3

u 1.1

1

"_0.9_ 0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

02O0

PdCr Gage 18-2Gage roctc_ (18 Or2)

/

//

/ II

40O

i..

I1

Temperot_ (K)

[] C 500 + T 500 0 C IC00 _ T 1000

2OO

190

180

170

160

150

140 --

130

120

110 --

_ too

} 9o8O

_ 60g so_ 4o

3O

2O

10

0

PdCr Gage 18-2Ooge Foc_or Vor_oUc,_ (18_)

n

I

0 C500 + TSO0

400 600 800

Te,-_l_, mtu_ (K)

o C 1000 _ T 1000

Figure 16.- Continued

26

2

1.9

1,8

1.7

I_ 1.5

g_ 1.4

1.3

1,2

1.1

12oo

2

1.9

1.8

1.7

1.6v

I_ 1.4

1.3

1.2

1.1

1

2O0

1.9 1

1.8

1.7

1.(5u

g_ 1,4 --

1.3 l

1.2

1,1

1

o C 500

PdCr Gage 09-1Gage F'OC_ (O9_GF1)

4OO

A

O +

oo

o o

5O0 800

Tempe,'o_r'e (K)

+ T 500 O C 10OO _ T 1000

PdCr Gage 09-1Cage Factor VoHa_on (O9 GF'I)

4-

2O0

o

t-

o

o

,x

_ mpemtu_ (K)

O C 500 + T 500 O C 1000 zi T 1000

Oi

8OO

PdCr Gage 09-2Ooge factor (09_0r2)

PdCr Gage 09-2Gage Factor Vat;at;on (O9 GFV2)

5

o

5

0

5

o

5

0

o

o

u+ _0 0

400 600 800 200 400 600

Tempe_bJre (K) Temperoture (K)

0 C 500 4- T 500 o C 10OO A T 10OO [3 C 500 + T 500 O C 10OO _ T 1000

8O0

PdCr Bar 10-1Cage Factor (10 Olrl}

b

PdCr Bar 10-1

Gage Fac_.r Vor;oUon (tO_GF_}

0

!

o

4O0 600 800 400 60O

Temperature {K} Temperature {K)

O C 500 4- T 500 O C 1000 ._ T 1OOO O C 500 + • 500 O C 10OO Z_ • 1OOO

8O0

Figure 17.- Gage Factor and Variation of PdCr Strain Gages on CuZr Bars

27

2

1.9

1.8

1.7

1.6

g_ 1.4

1.3

1.2

1,1

1

2

1.g

1.8

1.7

1.5

I_ 1.4

1.2

1,1

1

2

1.9

1.8

1.7

1.6

g

1.2

t.1

1

20O

20O

PdCr Gage 10-2_9e factor (10,_0r2)

Tempero_ur_ (K}

O C 500 ";- T 500 e C 1000 Z_ T 1000

PdCr Gage 11-1Gage Factor (11_.GF1}

ol

4O0 6OO

Temper_ur_ (K)

[] C 500 + T 500 O C 1000 _ T 1000

PdCr Gage 11-2Ooge Iro(:to_ (11._OF'2)

400 600

Ternperoture (K)

[] C 500 + T 500 o C 1000 /1 T 1000

BOO

800

8O0

2,4

22

20

18

16

14

v

b

_ 6

4

B

?

6

5

v

h.

g 2

1

0

4

}

2

I

g

B

_ 613 5

&32

1

0

200

t

o c 5o0

PdCr Gage 10-2Gage Factor VoHo{Lion (10_(]:'V2)

.I

D4- ....

#=

.i-

o •

o=A

6oo

Tem_r=turl (K)

+

O

OO

(3

O

A &

ol800

t" T 500 0 C 1000 ._. T I0(_

PdCr Gage 11-1Oage rocl_r Va6_;e. (11_GP¢1)

2OO

3

+4-

A

D6o

"remi:_rotunB (K)

+

El

o

°!

0 C 500 + T 500 0 C 1000 & T 1000

80O

PdCr Gage 11-2Oage Facto*- VoHotlon (11 OF'V2)

4O0 6OO

"rempemtu_ (K}

8O0

[] C 500 + 1" 500 0 C 1000 A T 1000

Figure 17.- Continued

28

1o

Strain Gage Bar Temperature GradientMo;"_holl F'umace (4--841>

C

E

I-

0

_,o x&-20

/7

-,o / \-50

-60--2 -1 0 I

Locok;o_ From Center (inches>

D 6261:- _t 1038F Q 1324F 6 1516F X 1BOOF 9 181iSF

Figure 18.- Axial Temperature Distribution On A Test Bar

The gage factor results from bar 03 indicated a higher gage factor than from

other PdCr gages (about 1.9 compared to 1.4). This was possibly because of Cr

depletion due to oxidation from long exposure to elevated temperature during

previous apparent strain testing. Addltlonal evidence of this was a gageresistance that decreased from about 60 to 40 Ohms during the apparent strain

testing. Also, it is possible that the Pd diffused to the wire surface,resultlng in electrlcal shunting of the PdCr wire. The gage factor results

from gage 18-2 indicated a continuous reduction in gage factor with time, the

last measurement being near zero. This was due to delamlnatlon of the Roklde

overcoat and loss of the gage bond to the precoat. Results from gages 10-I and

11-2 indicate erratic readings above 533K (500°F). For gage 10-1, the reasonwas not found but could be a recording malfunction or a loose connection in

the circuitry. For gage 11-2, the reason is probably a loose connection in the

gage circuitry (the gage was found to have an open circuit during the post-

test inspection).

Creev Data (PdCr)

Creep data for PdCr gages are shown in Figure 19. In each plot, data shown for

approxlmately the first hour represent the period of coollng from the maximum

temperature to the creep temperature, and the next i0 hours (1 through 11) is

the creep test period. The creep strain of 1DO0 mlcro-strain resulted in about

1400 mlcro-Ohms/Ohm (gage factor is about 1.4) of delta-R/R. Because creep is

the relaxation of strain in the cement and gage, creep must be in the opposite

direction from and no greater than the applled strain. The creep direction

would be minus for gage i and plus for gage 2 because of the bending strain.

The data shows that the drift is too great to measure any creep if it exists.

Except for the 700 and 755K results from gage 12-2, the direction or magnitude

does not fit the creep character.

BCL-3 GAGES

Maximum test temperature for each test is shown in Table II.

29

36

34

32

30

26E

_ _0

g: 18

12

10

8

8

4

2

?

E

_ ..4

g -6

_" -12

_ -14

-16

-18

-20

-22

PdCr Gage 04-1 Cycles 4CR, 5CR, 6CRCreep (÷1000 ue) I_c 89 (04 c_'rl)

_ .,-.,.._..,..,__+v_lk

L

2 .4 6 8

T;me {houma)

4CR (TO0_) ÷ 5CR (755K) o sc_ (86SK)

t"-,."k

PdCr Gage 05-1 Cycle 6CRCreep (.,,.1000 ue) a_ go (06 era'l)

t%_

\

lO t2

0 2 4 6 8 10 12

lnr,_ (hour_)

+ 6CR (_.6K)

Figure 19.- Creep of PdCr Strain Gages

E

._-Eo

g

!

7

xE

£

9

40

38

3_

34

32

5O

28

26

24

22

20

18

'16

14

12 --+

lC

PdCr Gage 04-2 Cycles 4CR, 5CR, 6CRC,'_ep (-lOOe_e) De,: 89 (04 cm'2)

I

J

L

.Jri

2 4. 6 8

I"1 4_1_ (700_) "t- 5CR (755K) 0 eC_t (_66K)

8

_i-4

-6

-8

-10

-12

--14

-15

-18

-20

-22

2O

_8

16

14

12

10

8

6

4

2

0

-2

-4

--8

-10

PdCr Gage 05-2 Cycle 6CRCreep (-_000 _) a_ 90 (oS_Cm'2)

I\

\

0 2

\

\

%

4 6

"_._ (hou,_)

* SCR (essK)

\'-,..

8 10

PdCr Gage 12-2 Cycles 4CR, 5CR, 6C_Cntep (-+000 .e) May go (_2_cm'2)

- l0 2 4 6 B 10

"nine (hou,_)

D 4CR (7_) + 5_ (7554<) O 6_ (811K)

12

i

3O

TABLE II.- BCL-3 STRAIN GAGES:

TESTS CONDUCTED AND MAXIMUM TEMPERATURES (K)

Bar Bar Heat Apparent Drift

Number Material Treat Strain

13 IN100 1172 1144

14 IN100 1172 1144

15 IN100 1172 1144

16 IN100 1172 1144

17 IN100 1172 1144

19 CuZr 839 811

20 CuZr 839 811

616

7O0

755

811

1144

1144

700

755

811

Gage

1144

1144

21 CuZr 833 811 811

22 CuZr 839 811 811

23 CuZr 839 811 811

24 CuZr 839 811

Creep

700

866

1144

700

755

811

Apparent Strain (BCL-3)

Apparent strain data for BCL-3 gages on IN100 bars are shown in Figure 20 and

on CuZr bars In Figure 21. On the first cycle, the bars were subjected to a

heat treat of 50°F above the established maximum test temperature for 30

minutes. Thls is the heat treatment recommended by the gage producer, Batelle-

Columbus Labs.

The results from gages on IN100 bars indicate a large change in slope between

the heat treat and the other two cycles. The second and third cycles are about

the same when the heating and coollng time histories are similar (bar 15, for

example). Tlme vs temperature plots for bars 13 and 15 are shown. Differences

between the second and third cycles are due to longer than planned heating or

cooling times caused by improper oven control (bar 13, for example). Thesedifferences are due to the known tlme/temperature dependency of the resistance

of the FeCrAI famlly of gage alloys. Data from the third cycle of gage 16-1

and from all three cycles of gage 16-2 were lost due to a data system

malfunction. Data from the first cycle, below 900K, from bar 17 were lost

because of an electrical power failure (local circuit breaker).

The results from gages on CuZr bars indicate better uniformity of the three

cycles because of more uniform temperature histories and low drift in the

range of 811K (1000"F).

31

BCL-.3 (;age 1.3-1 Cycle 1A, 1B,2A,2B,3A,3BApporll_ S_u'oin Jon 90 (13 _LL1)

5

0 L

_" -25 _

-35

--400.2 0.4 0.6 0.8 1

(3_ousond_)

Tempemtur_ (K)

0 IA + 1B 0 2A _, 2B X 3A ¢' 38

I1.2

BCL-5 Gage 15-2 Cycle 1A, 1B,2A,2B,3A,3BAp_r_nt Sl_;n ,ion 90 ('t3 /¢1.2)

5

0

I0 -- \

,o15

_0 ......... i_J

55

400,2 0.4 0.6 0.8 1

Cmo,so.d,)

Temperature (K)

O 1A ÷ 1B O _ -'- 2B X 3A 9 3B

1.2

_'_ --10

E

I _ -15

e_Eo

_ -2s

-35

-4O

BCL-3 Gage 14-1 Cycle 1A, 1B,2A,2B,3A,3BAppoint S_ra;n F'llb 90 (14_ALL1)

5.

x

0.2

o 1A

0.4 0.6 0.8 1

_m_ _)

+ IB o _ • 2B x 3A V

1.2

BCL-5 Gage 14-2 Cycle 1A, 1B,2A,2B,3A,3B

O

-5

-10

-15

-20

-25

-30

-35

-40

-45

0.2

\\

%

0.4 0.6 0.8 1

(l'l-,ouson_)

Ternpero_Jn_ (K)

0 IA + 1_ O _A A 2B X _ 9

1.2

--5

-10

8-15

E

; _ -2oEo

Eo

_ -_

-'x 5

-40

-45

BCL-3 Gage 15-1 Cycle 1A, 1B,2A,2B,3A,3B

\

Appclremt Stra;n Jan gO (15 ALLI)

\

%

0.2

[] 1A

0.4 0.6 0.8 1

(Tha.._a.c_)

Tempemtun_ (K)

+ IB O 2A t, _J_ × _ _ 3_

1.2

BCL-3 Gage 15-2 Cycle 1A, 1B,2A,2B,SA,3B_4_poclnt Stro|n Jon 90 (15 NJ-2)

o.s i

oi \

15

_0 --

25 --

N

_5

_0

45

0.2

\

.....

0.4

0 1A + IB O _]k

0.6 0.8 I

(Thouaands)

T,.'._ ratun_ (K)

_. 2B x .3A V 313

1.2

Figure 20.- Apparent Strain of BCL-3 Strain Gages on IN100 Bars

3Z

o

-5

_' -10

-15

c -20

E_ -25

¢ -30

-35

-4O

-45

BCL-3 Gage 16-1Apporlmt. Stro;n rBb 90 (16_ALL1)

\\

X,

Cycles 1A, 1B,2A,2B

0.2 0.4

in 1A

,1

1.2

BCL-3 Gage 17-1 Cycle 1A, 1B,2A,2B,3A,3BApporen_. Strain May go (17_ALL1)

0

--5

"_ --15

_ -2ouo-i

E -25

I[ --30

0 -35v

-4O

\

--45

0.2 0.4 0.6 O.B 1

Te rope m_r_re (K}

[] IA + IB O 2A _, 2B X 3A V 3B

1.2

BCL-,3 Gage 1,3-1 Cycle 1A, 1B,2A,2B,3A,3BAp poPlm_. Stroin (13 ALT1)

t::!28 _26 - _ i_-IB-.6.

_--B,-,I_-- _ _,_e.. -24

22

20

18

16

14

12

10

8

$

4

2

0

0.2 0.4 0.6 0.8

Tempi m_Jnl (K)

O Cycle* I, 2 & 3

= : J

1 1.2

BCL-3 Gage 17-2 Cycle 1A, 1B,2A,2B,3A,SBAppare_L Stroi_ May 90 (17_ALL2)

0

5

0

lC

t_

H

¢(

4_0.2

\%

_, _.

[] IA + 1B

0.4 0.6 0,B I 1.2

T._p_tur_ (K)

o 2A A 2B x 3A v 3B

BCL-3 Gage 15-1 Cycle IA, 1B,2A,2B,3A,3BAppanmt Sb_in (15 ALT1)

=' ] I21 _ "

2(

_ '_.._ ,_ _

0.2 0.4 0.6 0.8 1C_,_,.,J o,_',,)

O Cycle_ 1. 2 & 3

1.2

Figure 20.- Continued

33

,57

,.,._Eo

o

v

57

£

T

g

0

-2

--4

--6

-8

--10

--12

--t4

--16

-18

--20

-22

--24

--26

BCL-3 Gage 19-1 Cycle IA, 1B,2A,2B,3A,3BAplaart._. Stre;n Feb 90 (19 ALL1)

2

%

[3 1A

400 6OO 8OO

T=mperoture (K)

÷ lIB O 2A & 2B X 3A V 38

BCL-5 Gage 19-2 Cycle 1A, IB,2A,2B,SA,SBAppar'e_ S_in Feb go (19 ALL2)

2OO

a_

O 1A + 1B 0 2A

4OO 643O 80O

Temp=mture (K)

z= 2B x 3A V 3B

BCL-3 Gage 20-1 Cycle 1A, 1B,2A,2B,3A,3BApponmt S_mTn Feb 90 (20 ALL1)

2

0

-2

-4

-6

-8

-10

-12

-14

-16

-18

-20

-22

-24

-262O0

rt 1A

BCL-3 Gage 20-2 Cycle 1A, tB,2A,2B,SA,3B_perent S_ol. r,=b 9O (2OJCL2)

2

\%

\

4OO 6O0 8OO 20O 40O 60O 800

TernF_em_r_ (K) Tmmperot_t1_ (K)

+ IB c. _ A 2B X _ V 3B _ D IA ÷ IB 0 _ A 2B X _ V

BCL-3 Gage 21-1 Cycle 1A, 1B,2A,2B,3A,3BAp_amn _. S_.roln Mar gO (21 ALL1)

2

o

-2 _-4

-6 ,%

-- 10 )1-12

,,%.-14 '_1_-

--16 -- --

-1B ' --" '_-_,

-_= _ _--24

--26

[] 1A

BCL-3 Gage 21-2 Cycle 1A, 1B,2A,2B,3A,3BApparent _tra;n Mot 90 (21 ALL2)

2

6

-%

400 1500 800 200 400 600 800

Temperature (K) Tempemtune (K)

+ IB O 2A & 2B X 3_ _' _B [] IA + IB O 2A & 2B X 3A _ 31B

Figure 21.- Apparent Strain Of BCL-3 Strain Gages On CuZr Bars

34

O

-2

6 -s

E -8

8"; -loe_o

_ -_2Ea

;'_ -_,--16

-20

--22

--24

--26

.-_ --4

_6 i

_'_ -_o1 Ioe_

= -12

_ -16

v --20

BCL-3 Gage 22-1 Cycle IA, 1B,2A,2B,3A,3BAp_t S_in Ap" 90 (22_ALL1)

2

%e-_1

?8

Tempem_ (K)

[3 1A + 1B O 2A A 2B X _ V 3B

BCL-3 Gage 23-1 Cycle 1A, 1B,2A,2B,3A,3B_opo_ S_,a;n &at SO (23__L1)

2

o J

--22

-24

-26

\lk

%

"-C _ _ __

0

-2

200 400 600 8OO

Tem pe,"uture (K)

O IA ÷ 1B O 2A & 2B X _ V _B

BCL-3 Gage 24-1 Cycle 1A,1B,2A,2B,3A,SBAppo_t Slro;n _ 90 (24__.L1)

2

--4

-6

_ -loeg_ _ -12

7_

_V

_ --18 --

v --20

--22

--24

--26

[] IA ,I- 1B O 2_ _ 2B X 3A V 36

BCL-3 Gage 22-2 Cycle 1A, 1B,2A,2B,3A,3BAppa,"_t Stro_ Apt 90 (_._. N.I.2)

2

° _.

%,,,,

"%%.

I200 400 600 800

Tempem_ (K)

O IA + 1B O 2A & 2B X 3A _ 3B

BCL-3 Gage 23-2 Cycle 1A, l_,2A,215,,3A,OUAp_t Sb_n AW 90 (23_/_Lt..2)

2

O

i-8

I0 --

12

14

16

18

ZO

Z2

Z4

26

%

g-

Tempem_,_ (K)

O 1A + 1B O _ t_ 2B X 3A _ 3B

BCL-3 Gage 24-2 Cycle IA, IB,2A,2B,$A,_B_opo_t¢_ SL,'ain Ap_ 90 (24_N.I-2)

I

.-._

Temperature (K)

0 1A + 1_ 0 2A t_ 2B X 3A _ .38

Figure 21.- Continued

35

Drift Data (BCL-3)

Data for BCL-3 gages are shown in Figure 22. In each plot, data shown for

approximately the first hour represents the period of cooling from the maximum

temperature to the drift temperature, and the next I0 hours (i through n) is

the drift test period.

The following is a summary of the drift rates (in micro-0hms/0hm per hour).

Bar-Gage Type 616K 700K 755K 811K I144K

(650°F) (80O°F)_ (900°F) (1000"F) (1600eF)

13-1 IN100 +100 -550 -260 -20 -230

13-2 IN100 +100 -550 -260 -20 -220

20-1 CuZr - -410 -5 +40

20-2 CuZr - -420 -5 +30

w

w

Gage Factor Data (_CL-3)

Gage factor data for BCL-3 gages on IN100 bars are shown in Figure 23 and on

CuZr bars in Figure 24. For each gage, the gage factor and gage factor

variation are shown. Each point on the gage factor plot is the mean of the

four measurements described in the "Test Procedure" of Section 3. The

variation is defined as two times the standard deviation of those four

measurements as a percent of the mean.

The results from INIO0 bar 15 indicate a lower than expected measurement and

from IN100 bar 16, a higher than expected measurement of gage factor, based on

the published value of about 2.4 (room temperature). On bar 16, the reference

strain measurement was repeated twice (with new reference gages), but the

excessive measured gage factor was not explained. Simple bend load testing was

conducted in an attempt to varify the results, but the results indicate that

the high measured values are invalid (see Appendix). The measurements could be

due to defects in the cast material. The gage factors of the gages on the CuZr

bars agreed more closely with each other.

Creep Data (BCL-3)

Creep data for BCL-3 gages are shown in Figure 25. In each plot, data shown

for approximately the first hour represents the period of cooling from the

maximum temperature to the creep temperature, and the next i0 hours (I through

ii) is the creep test period. The creep strain of I000 micro-strain resulted

in about 2400 micro-0hms/0hm (gage factor is about 2.4) of _R/R. Because

creep is the relaxation of strain in the cement and gage, creep must be in the

opposite direction from and no greater than the applied strain. The creep

direction would be minus for gage 1 and plus for gage 2 because of the bending

strain.

At all temperatures, the change in AR/R was in the same direction for both

gages i and 2. This indicated that the change was due to drift and not creep.

At 755, 811 and 866K (900, 1000 and II00°F), the change was very small,

indicating that any creep or drift that may be present was very small.

36

-28

"E -2g

-30

_'; -31I '0e=.

. -32

¢" -34

-35

BCL-3 Gage 15-1 Cycles 4, 5, 6, 7 & 80,-[_ Jan 90 (13_0RT_)

-26

-27

-36

-37

-38

-16

-17

-1B

_ -20

g'; -21I 10egv _ -22

¢ --24o

i\ _+"\

I2 4

•+ 7_

6 8 10

"rime (hour_)

O 755K /t 811K X 1144K

BCL-5 Gage 20-1 Cycles 4, 5 & 6_f_ Feb 90 (_ _rl)

12

-25

--26t

--27 _ ----

/--28

0 2 4 6

"nine (hour=)

a 4 (7co,:) + s (';'_K)

-28

-29

-30

-31

E -32

ii -34

-3s

i -36

-3E

-4(

8 10 12 0

BCL-3 Gage 13-2 Cycles 4, 5, 6, 7 & 8_ Jan 90 (13 OR_2)

_,_.

---o tJ_+ I 1_

O 618K

2 4 6 8 10

_m¢ (bout'l)

"1" 70OK O 75_K A 811K X 114.4K

12

BCL-3 Gage 20-2 Cycles 4, 5 & 6c_ r=b90 (2o om_)

-1+1 1--17 !

-,+ ........,....t.....1..l

-26 t-2"/

-282 4 6

"n_e (_,._)

o _ (7oo_) + s (Ts._)

Figure 22.- Drift of BCL-3 Strain Gages

37

3.2

3

2.8

2.6

2.4

_ 2,2

1.6

1.4

1.2

1

3.2

3

2.8

2.6

2.4

"_ 2.2

g 28

1,8

1.6

1,4

1.2

1

3.2

3

2.8

2.6

2.4

u 2.2

1.8

1.6

1.4

1.2

1

0.2

0,2

BCL-3 Gage 15-1Cage Fact,or (15,_Olrl)

BCL-3 Gage 15-1Oage roch3r Vor{oUo_ (15_OFV1)

!

Ib

0.4 0.6 0.8

[3 C500 + TS00 0 C 1000 6 T 1000

t

v

1.2 0.2

t"

O

&

v

8

o

m Ao

g

J3

0

4-

0

D

0

0.4 0.6 0.B 1

(_ouson_)Temperature (K)

O C 500 + T 500 O C 1000 A T 1000

0.2

BCL-,3 Gage 15-2Oage FQctor (15_or2)

.t-

0.4 0,6 O.B 1

Tempem_'l (K)

0 C 500 I" T 500 O C 1000 -_ T 1000

BCL-5 Gage 16-1Gnge Foctor (16 OF1)

L°°

• 1-

I0.4 0.6 O.B !

(_sands)Tem pe m_oJrl_ (K)

O C 500 + T 500 O C 1000 & T 1000

f,

5

2

1.2 0.2 0.4

BCL-3 Gage 15-2Gage Factor Vo_ot'c,n (15_GFV2)

D

%o

o

oA

o _' to

•I- A

[] •4-

÷4,

0.2 0.4 0.6 0.8

C500 + T _0 0 CI000 _ TIO00

BCL-5 Gage 16-1Ooge Foctor VaHatlo_ (16 OF'V1)

0

4,

+

0.6 O.B

(lV, c_.a_as)Tempe n_u_ (K)

O C50_ ÷ TS00

Ao{4-

O

0

A

Ao

o

0

¢ C 1000 & T 10oo

Figure 23.- Gage Factor and Variation of BCL-3 Strain Gages on INI00 Bars

o 5÷

+

1.2

÷

G

1.2

D

38

28

2.4

_. 2'2

1.e!

1.6

1.4

1.2

1

3.2

3

2.8

2+6

2.4

. 2.2

g 2

1.8

1.6

1.4

1.2

1

3.2

3

2.6

2.4

_ 2.2

g 2

1.8

1.6

1.4

1.2

1

0.2

0.2

0.2

BCL-3 Gage 16-2Go8e Irec_ (16,_0r2)

I,-i

%

I,

0.6 0.8 1

Temperature (K)

÷ T 500 O C 1000 6 T _000

BCL-3 Gage 17-1Gage F'octoe (17._GF'1)

t1.2

I

0.4 0.6 0.8 1

TempembJre {K)

D C 500 ÷ T 500 O C 1000 _, T 1000

BCL-5 Gage 17-2,"-,',ge roctor (17_0F2)

t

0,4 0.6 0.8 1

Tempera_uee (K)

D C 500 + T 500 0 C 1000 _ T 1000

1.2

10

9

8

7

6

_ 5

! +

1

O

0,2

0.2

BCL-5 Gage 16-2Gage factor VoHatio. (16_C_V2)

o

om _

o

.+.

+¢

c

+_

.k

0.4 0.6 O.B_n'_ot._ond s)

Tempe,'otu_ (K)

0 C 500 + T 500 0 C 1000 _ T 1000

BCL-3 Gage 17-1Ooge Facto+" VoHot;on (17_GFV1)

rl

, I

°° 11_--

1.2

0.2

9

4D ÷

#

¢

[]

13 el .I. +

_ o

o., o._ o._ _ _._('_.o,,a.)

D C 500 + T 500 0 C 1000 _ T 1000

BCL-3 Gage 17-2Oage Factor Varlet;on (17 GFV2)

O

,o

o

J_s +

+i +

,-t

0.4 0.6 0.8 1C'_oosa-_)

Te,",npe,'atu _ (K)

[3 C 500 + T 500 O C 1000 _, T tO00

[3

D

[]

++^

Figure 23.- Continued

39

BCL-3 Gage 21-I BCL-3 Gage 21-IOoge Factor (21._0_'I) Gage roc_r Valor;on (21 Of"V1)

3.2

3

2.B i

2+6

2.4

_ 2.2

_ 28

1.8

A

u m

1,4

÷ []

1.2 - t-

0+2 0.4 0.6 0.8 1

C_ou,,,d,)

Temperature (K)

[] C 500 + T 500 O C 1000 Z_ T 1000

1.2

50

35

3O

A

;_ 20

0.2

A +

o

0

o _

÷ &+

0.4 0.6 O.B

(l_o_ond=}

Te r_pem_wre (K)

[] CS(X) + TSOO O C1000 & T1000

1.2

3.2

3

2.8

2.6

2.4

2.2?.

g 2

1.8

1.6

t.4

1.0

1

3.2

3

2.8

2.6

2.4

u 2.2

g 2

1.8

!i

1.6+

1,4

1.2

1

BCL-3 Gage 21-2Goge F'octo_ (21_Gr2)

0.2

o j q

+

+

0.4 0.6 0.8 1

('mou=ond=)Temperature (K)

O C 500 + T 500 O C 1000 _, T 1000

BCL-3 Gage 22-IGag= Foct,_r (22.0F'I)

0.2

+

t.2

o

I-

o ; ""At

u

0.6 0.8(Thousand/)

"Tem_m_.ure (K)

÷ T500

z--

00.2

4(

3_

2_

g +

BCL-3 Gage 21-2Gage racer V=Hotio_ (21 OFV2)

_0

A

+O

! o@ @

0.4 0.6 0.8 1

Cn_ov=on_)Tempe_otur= (K)

(3 C5OO + TSOO O C1000 _ TIOOO

BCL-3 Gage 22-IGoge F'octor VoHot_ (22 C#'V1)

[

o

++

A

o

0.4

@

+ 6o

@

+1@

O+6

+

÷

O

I+* le

/,

0.8 10.4 I 1.2 0.2

13 C 500 O C 1000 & T 1000 n C 500 + T 5OO O C 10OO & T 1000

1.2

1.2

Figure 24.- Gage Factor and Variation of BCL-3 Strain Gages on CuZr Bars

40

,3.2

3

2.8

2.6

2.4

_ 2.2

g 2

1,8

1.6

1.4

L2

1

3.2

3

2.8

2.5

2.4

_u 2,2

_ 2

1.8

1.6

1.4

1.2

1

2.8

2.6

2.4

_ 2.2

g 2

1.8

1.6

1.4

1.2

1

0.2

0,2

0.2

1-

BCL-3 Gage 22-2age [ocl_* (22 at2)

i i

+> I iQ t.

I

ID

1

0,4 0.5 0.8

Ci>,ou.a,,.,d.)

Tempera'tyre (K)

[_ C 500 + T 500 o C 1000 A T 1000

BCL-3 Gage 23-1Goge F'octor (23._GF1)

; i I+,i

0.4 0.6 0.8

(Thougondl)

Te_peroture (_<)

q1

D C 500 + T 500 0 C 1000 /Z T 1000

BCL-3 Gage 25-2Gage Foct_" (23_0r2)

, i

0.4

I_0

D

|

+

+

0.6

i

+

o

Ka<>°1

0.8 1

Temperature (K)

a C 500 + T 500 o C tO00 .'- T tO00

1,2

1.2

1.2

40

35

30

25

!'+

5

0

0.2

5(

4(

3!

3<

g

40

35

30

25

_" 2o

5

i o

BCL-3 Gage 22-2Goge Fac_o_ Vor;a6on (22_GrV2)

÷Q

6 -t-

0.4

O C 5O0

0.6 O B 1

Tempe,_ (K)

+ T 500 0 C 1000 Z_ T 10C_

BCL-3 Gage 23-1Gage Foctor VaHat_n (23 GFV1)

r_ u

1.2

÷

0.2

io

o + " Im

I_ + + i

0.4 0.6 0.8

Temperclture (K)

[] C 500 t- T 500 0 C 1000 _ T 1000

BCL-5 Cage 2,5-2Gage Factor Vo_at_on (23_GF'V2)

1.2

g0,2 0.4

C 5O0

^ L_

J_

+

0.6

t

0.8

(l_oulond=l}

TernperO_re (K)

+ T 500 0 C 1000 _, T 1000

1.2

Figure 24.- Continued

41

-44

-46

--48

.; -soI I=E o= -s:

o_-6,;'_ -GG_" -.68

-80

0-.--62

BCL-3 Goge 16-1 Cycles 4CR, 5CR & 6CRCreep (+1000 ue) Mar 90 (1G CRT1)

-38 /

--42 ._

/

-64

-6G

-68

--4

-6

?8 -8_" --10

_._ -+2

E o -16

;_ -,6_" -=o

a -22

--24

-26

-28

0 2 4 6 8 10 12

"nine (ho_)

O 4CR {70OK) ÷ 5CR (866K) o 6CR (114-4K)

BCL-3 Guge 21-1 Cycles 4CR, 5CR & 6CRCreep (+1000 ue) Mot gO (21 CRTI)

I l

.... i .... • .....

2 4 6 8

"nine (h_nl)

o 4CR (70OK) , 5OR (76.SK) ¢ 6cm (81_K)

lO 12

BCL-3 Guge 16-2 Cycles 4CR, 5CR & 6CRCroup (-1000 ue) Mot 90 (16_CRT2)

/

]

Bs

_BB U

o 2 4 6 6 10 12

rl 4CR (70OK) + 8C_ (866K) O 6CR (1144K)

BCL-3 Goge 21-2 Cycles 4CR, 5CR & 6CRCreep (--1000 ue) Mot 90 (21_¢RT2)

0

-2

-4

-6

--8

-10

-12

i -14-16

--1a

-20

_ -,__ --24

-2g

-26

..... :::::::::::::::::::::::

0 2 4 8 8 10

n,,'ne (hour)

0 4C_ (70OK} + 8CR (758K) O 6CR (81 tK)

4

t

BCL-3 Bur 16 Creep Diff.1000 u--stroifl (Re_O--Re=l)/2 (16 CRO)

3.2

3.1

_ 2.9

f_1 2.8

_ _

'o-_ _.4

2+3 --

_ 2.2

2.1 @,_

20

o 4c:R (_'oo_)

ti+;_:

4 6 6 10 12

+ 5cR (866K) o 6C.S_(1144K)

BCL-5 Bor 21 Creep Diff._000 u-_rU'o;n (R,,_--R_)/2 (2LC_O)

-0.82 I I

-0.88 ....

-0.9

-0.96 _

-0.98 -- -- 'XBI _

-'-I.04 --'--

-_Jo6 -" -_P'_ _,-H_-- 1,08

--1.1 I

--1.12

--1.t4

-1.150 2 4 6 B 10

1;m_ (ho_)

[] 4CR (700K) "+ 5CR (756K) ,0 6C_ (811K)

Figure 25.- Creep of BCL-3 Strain Gages

42

Some additional analysis was performed on data from bars on which both gageswere functional. If the drift character was the same on both gages, the drift

and creep would be separable because the strains are equal and opposite.

Therefore, the creep would be found from half of the difference of the signals

(and the drift from half of the sum). This type of analysis was done for BCL-3bars 16 and 21. (The PdCr gages with high drift did not have good enough

uniformity to obtain meaningful results.) The BCL-3 gages did have good

uniformity and the results indicated very low (less than 5 micro-0hms/0hm per

hour) creep. The results of this differential analysis for bars 16 and 21 are

shown in Figure 25.

COMPARISON OF RESULTS

Comparison of PdCr to BCL-3 on IN100

Apparent strain of PdCr is less than that of BCL-3 up to the temperature limit

of PdCr, 866K (II00°F). Above that temperature, BCL-3 has better apparent

strain stability, probably due to better oxidation resistance. Drift of PdCr

is less than that of BCL-3, but they cannot be compared above SilK (1000°F),

the maximum drift-test temperature for PdCr. Gage factor of PdCr is less than

that of BCL-3 (1.4 vs 2.4), because of slightly lower strain sensitivity of

the PdCE wire and the desensitization caused by the platinum temperature

compensation element. Creep of the two gage types can not be compared because,

for the PdCr, drift hides any creep that may be present. Creep of BCL-3 is

very small.

Comparison of PdCr to BCL-3 on CuZr

Comparison may be made only up to the temperature limit of the CuZr substrate,

811K (1000°F). Apparent strain of PdCr is less than that of the BCL-3. Drift

of PdCr is less than that of BCL-3. Gage factor and creep comparisons are the

same as for IN100, above.

ComDarlson of INI00 to CuZr for PdCr

Apparent strain, drift and gage factor results for PdCr were similar for IN100

and CuZr. Creep results can not be compared because drift hides any creep that

may be present.

Comparison of IN100 to CuZr for BCL-3

Apparent strain and apparent strain stability were greater for INI00, due to

the higher maximum test temperature, I144K (1600"F) vs SilK (1000°F). Thermal

expansion accounts for only a small fraction of the apparent strain.

Differences due to the slightly higher temperature-coefflclent-of-expansion of

CuZr would not be noticeable. Drift results were similar for the two substrates

at the same temperatures. Gage factor consistency, gage to gage, was better

for CuZr. However, variation among the four readings for individual gages

(gage factor variation plots) was worse for CuZr. This was thought to possibly

be related to yield of the CuZr bar, but no evidence of yield was found.

Review of the material properties (from Nippert) indicates that the yield

strain is higher than I000 mlcro-straln, even at SilK (1000°F). Also, the

strain measurements, made during gage factor testing, were compared to

determine if the first deflection differed from subsequent deflections. No

differences were found. The large gage factor variation has not been explalned.

Creep was very low for both substrates.

43

INSULATION RESISTANCE DATA

During testing, insulation resistance was measured for each gage at each data

point. These data were plotted for selected apparent strain cycles of PdCr bar

06 and BCL-3 bars 15, 17 and 24. The results indicate that the insulation

resistance drops below i megohm at about 900K (II61°F). This is shown for bar

17 (BCL-3 on INI00) In Figure 26. The results for the alumlnalzlrconla powder

mix were similar to Rokide up to 866K (II00°F), the maximum temperature for

those bars. The measurement method inherently provided better accuracy at low

resistance levels than at high. This accounted for the scatter at low

temperature (and high resistance).

1000

BCL-3 Gages 17-1 & 2 Cycle 2A (Heating)

Insulation Resistance May 90 (17_2ARI)

insulation Resistance (kOhms)100000

1o0oo a I

L

100 _ -- .--___T

10300 400 500 e00 700 coo 900 1000 1100 1200.

Temperature (K)

Gage 1 _ Gage 2

BCL-3 Gages 17-1 & 2 Cycle 2B (Cooling)Insulation Resistance May 90 (17_2BRI)

insulation Realalanoe (kOhma)

k r--l

300 400 500 600 700 800

..-.

l900 1000 1100 1200

Temperature (K)

-- Gage 1 _ Gage 2

Figure 26.- Insulation Resistance

44

THERMO-ELECTRICITY DATA

Thermo-electricity was measured at each data point by measuring the bridge

signal with both positive and negative excitation. This was calculated in the

same way as the resistance change ( -R/R) except that the signal difference

(rather than the sum) was used. The units represent the equivalent -R/Rindicated by the bridge signal due to thermo-electricity. This parameter was

plotted for selected apparent strain cycles for PdCr bar 05 and BCL-3 bars 17and 24. The thermo-electricity range during heating and cooling cycles are asfollows:

T'yDe Cycle Range (mlcro-0hms/0hm)

PdCr Heating 30

PdCr Cooling 30

BCL-3 Heating 270

BCL-3 Cooling 120

The amount of thermo-electrlclty depend on the type of grid and lead wire and

on the temperature gradient along the path. It is generally less during

cooling cycles than heating cycles because cooling cycle are slower and the

gradients less. Results are shown in Figure 27.

POST-TEST INSPECTION

For each test bar, gage circuit and insulation resistance were measured and

the installation was visually examined for defects. Of the 26 tested PdCr

gages, five were found to have an open circuit. All open circuits were located

at the weld of the Pt grid to the noncommon lead wire. Of the 22 tested BCL-3

gages, one was found to have an open circuit. It was located near the center

of the grid. All gages were found to have insulation resistance greater than

20 megohms except for two gages with about one megohm. The general appearance

of the precoats and overcoats was excellent. Only one gage had evidence of

overcoat delamlnatlon.

Resistance measurements of all the gages and compensation elements were made

after testing and compared to those made prior to testing. The results are

shown in Figure 28.

Two additional tests were conducted to determine the thermal stability of the

gage connection box and the self-heatlng character of the gages. In the first

test, with gages connected to the system, the connection box was heated to

measure any output caused by temperature change of the bridge resistors. The

box was heated over a range of IIK (20"F) and the output was small (about 200

micro-0hms per Ohm) compared to the thermal performance of the gages, but

significant relative to strain measurement accuracy objectives. The results

are shown in Figure 29. In the second, with PdCr gages connected to the

system, output was recorded with several levels of excitation to determine the

shift due to gage heating. The results are shown in Figure 30. The two data

points at each excitation level were recorded about 80 seconds apart. At the

5-volt level used in this program, the self-heating effect was small (about 20

mlcro-0hms/Ohm). The power density of the gages as used in this program was

considered acceptable (about .76 watts per square inch for BCL-3 and 1.16

watts per square inch for PdCr).

45

tO

"E" -10

oC

_1 -20

oL.¥E

-30

-4O

PdCr Gages 05-1 & 2 Cycle 2A (Heating)

-5O

#

jv200 400 600 800

Temperature (K)

D Gage 1 + Gage 2

-5O

IN i00

PdCr Gages 05-1 & 2 Cycle 2B (Cooling)Tl_ermo--elec{r;ci{y Jan gO (05_2B't'E)

5OO 50O 7O0

Temperature (K)

Q Gage 1 + Gage 2

gag

BCL-5 Gages 17-1 & 2 Cycle 2A (Heating)_em'no--elec{r;c}{y May 90 (17_2ATD

f

_q

/

0.3 0.5 0.7 0.9 1.1

(_,o,d,_

Tempen_ure (K)

O Gage I + Gage 2

140

120

100

8O

60

"E 4o

{ 2oF o

_ -20

.V --40Ev

-so-80

--120

--140

--180

m

F

J

BCL-3 Gages 24-1 & 2 Cycle 2A (Heating)Thermo--elect_clty Apt 90 (24_2AT_

180

180

} ,°

20 _

_ -20

-40

--6O

-8O

-100

\\

500

TempembJR (K)

ID Ooge 1 + Ooge 2

7OO

BCL-5 Gages 17-1 & 2 Cycle 2B (Cooling)"rt_o--,.ech4c&y I_oy 90 (11 2B1"£)

I

k_, /P

-120

-140

-1600.3 0.5

140

120

100

80

-- 60

"_ 4o

_ ,o

_ °-- Io -20

._ -40

_ -60

-80

-$00

IN i00

{

Z

900

CuZr

%

0,7

C_o_,o.d,)TempemhJre (K)

O Ooge 1 + Gage 2

0.9 1.1

i

9OO

Figure 27.- Thermo-electricity

46

70

Resistance Change of PdCr GagesPdOr [$m-n eft|

uu

1+

60

5O

40

30

20

10

0

:[

-' "_L_L_L_' _ .... L '_ ....o,o_b_r_h_rg_r_;k,110,,_ 1_ ,t,o,t,,11,2',b. 1_,+1_+'11206-207-20e-20g-210-21 I-212-218-2_-226-2

Bor and Cage Humber

Resistance Change of PdCr GagesI_ Element

o1'--11o2'-110g-01-202-203-204-205-206-207-208-209-210-211-212-218-225-228--2

Bor oncl Gage Number

I_ Pr_-_,t _ Po,_--_s*

130

120

110 !

I00

90

80

70

SO

50

40

30

20

10

0

Resistance Change of BCL-5 GagesBy Bor--l_gm

" " L ' _ L " " ' _ --1_111+ ills 111_-11_ 1119 1t_o-11_1 1122 112s-112, ,I,_-2 1,-2 1.s-2 is-2 1+'-_ 1+-2 _-2 21-2 ,,-2 m._-_2,-2

_Ot omd Goge N,Mn_N_P

Figure 28.- Strain Gage Resistance Before and After Testing

47

Connection Box StabilityEqui_nl_nt Apporw_t St,,l_;n (THERMC)

--100

-15o _-\

7 -2ce __...

"_ -250 _,

._ -20 "-. --__..._.___ _ _v

Do -400 _ _ "-,-

--4,.5O ,- _

--500

298 300 302 _1 306 308

Tem_t_ mt_r_ (k)

0 Gage t + Gage 2

310

Figure 29.- Strain Gage Zero Shift from Heating due to Excitation

?

E

E

&

s

-120

- 130

-140

-150

-160

-170

-180

-t90

-200

-210

-220

-230

-240

-250

-260

-270

-280

-290

-300

-310

-320

i _ ¢

Self Heating from ExcitationIEqu_atent Apl_t Sb'oin 014ERMO)

la3

B

B

¢

3 5

E_cR_.;o_ (v de)

Gage I + Gage 2

7 9

Figure 30.- Bridge Completion Network Thermal Stability

48

SECTION 5.0

CONCLUSIONS

PdCr GAGES

O Exposure to temperatures above 866K (II00°F) resulted in an increase in

the temperature-coefflclent-of-reslstance (TCR), probably due to

selective oxidation of the Cr.

Pt is an effective thermal compensation material. The resistance ratio

of PdCr to Pt should be about 18:1. This will allow a bridge ratio of

i:i and provide compensation for thermal resistance change in the leads.

o The drift rate was reduced by adding a NiCrAI coating to the Rokide

overcoat. Use of flame spray AI203/ZrO 2 overcoat did not reduce

drift rate significantly within the limits of this program.

BCL-3 GAGES

o Resistance stability is good above 800K (981°F). For measurement between

800 and I144K (981 and 1600"F), BCL-3 can be a useful gage wire.

Drift is high in the temperature range of 700 to 755K (800 to 900°F).

This results in tlme-dependent apparent-strain character, similar to

other FeCrAI strain gage alloys.

GENERAL

o Insulation resistance is less than one megohm above 900K (II61°F). This

agrees with other experience with Rokide.

o Thermo-electric effect for both gage/lead combinations is low, but that

of PdCr is less than BCL-3.

6.0 REFERENCES

i. Hulse, C. 0., Bailey, R. S. and Lemkey, F. D., "High Temperature Static

Strain Gage Development Program", R85-915952-13, United Technologies

Research Center, NASA Contract NAS3-23169, March, 1985.

2. Lemcoe, M. M., "Development of Electrical Resistance Strain Gage System

for Use to 2000°F '', Paper 75-572 Instrument Society of America, 1975.

49

APPENDIX

ATTEMPTED GAGE FACTOR VERIFICATION OF BAR 16 (BCL-3 ON IN100)

Because the gage factor measurements are higher than expected (approximately

3.0 rather than the publlshed 2.4), slmple room temperature bend load tests

were conducted on bars 15, 16 and 17 in an attempt to verify the measurements.However, the high measurements were not substantiated by these tests and are

probably invalid (although not explained).

The bars were clamped in a fixture and vise and a 27 pound weight was hung on

the other end while measurements were made with a portable strain indicator.

Reference gages were not used because in this loading mode, strain is not

constant along the length (and would be lower at the reference gage location).

Therefore, the exact strain of the bar was not measured, but the relativesensitivity of the five gages was determined. These measurements were made for

gages 15-1, 16-1, 16-2_ 17-i and 17-2 (gage 15-2 was found to have on opencircuit at the end of the scheduled test program). All the measurements were

referenced to gage 15-1 (ratios of sensitivities of the other gage to that of

gaze 15-1 were calculated). Similar ratios were calculated for the origlnalgage factor data for these gages.

The results, shown in Figure A-I, indicate that the sensitivities of all of

these gages are within about 20% of that of gage 15-1. The original gagefactor data indicates that gages 16-I and 16-2 have sensitivities about 60%higher than gage 15-1.

1.7

Bors 15. 16 & 17

O

D-p

+

0

o

r_

b-

I;oio

O

1.6

1.5

1.4

1.3

1.2

1.1

1 "=

0.9

<>

A

A

+

m

<)

o

0.8 I I I I I

15-1 16-1 16-2 17-1 17-2

Bor-Goge

O 0Hg_nol Comp. + 0Hg_nol Ten. o Vorlflcot;on Comp. d Vor_cation Ten.

Figure AI.- Gage Factor Verification Test Data for BCL-3 Gages on IN100 Bars

at Room Temperature. Ratio of Sensitivities of Gages are Relativeto that of Gage 15-i

50

1.REPORT NO. 2. GOVERNMENT ACCESSION NO. 3.RECIPIENT'S CATALOG NO.

NASA CR -189101

4.TITLE AND SUBTITLE

High Temperature Strain Gage for Hypersonic AircraftDevelopment Applications

7.AUTHOR(S)

W. L. Anderson and H. P. Grant

9.PERFORMING ORGANIZATION NAME AND ADDRESS

IUNITED TECHNOLOGIES CORPORATION

iPratt & Whitney

Commercial Engine Business

12. SPONSORING AGENCY NAME AND ADDRESS

Natlonal Aeronautics and Space Administration

Lewis Research Center

21000 Brookpark Road, Cleveland, Ohio 44135

5. REPORT DATE

February 1992

6. PERFORMING ORG. CODE

8. PERFORMING ORG. REPT. NO.

PWA 6141

i0. WORK UNIT NO.

Ii. CONTRACT OR GRANT NO.

NAS3-25410

13.TYPE REPT / PERIOD COVERED

Contractor Report

14. SPONSORING AGENCY CODE

15. SUPPLEMENTARY NOTES

Dr. Mary Zeller, Project Manager, NASA Lewis Research Center, Cleveland, Ohio

44135

16. ABSTRACT

An experimental evaluation of Pd13% Cr and of BCL-3 alloy wire strain gages wasconducted on IN100 and Cu .15% Zr alloy substrates. Testing included apparent strain,

drift, gage factor and creep. Maximum test temperature was I144K (1600"F). The PdCr

gages incorporated Pt temperature-compensatlon elements. The PdCr gages were found to

have good resistance stablllty below 866K (II00°F). The BCL-3 gages were found to havegood resistance stabillty above 800K (981"F), but high drift around 700K (800"F).

17. KEY WORDS (SUGGESTED BY AUTHOR(S)

Strain Gages, PdCr Gages, BCL-3 Gages,

Apparent Strain, Drift, Gage Factor,

Creep

18. DISTRIBUTION STATEMENT

19. SECURITY CLASS THIS (REPT) 20. SECURITY CLASS THIS (PAGE)

Unclassified22. PRICE *Unclassified 21. NO. PGS

51