NOTICE: When government or other drawings, speci-fications or other data are used for any purposeother than in connection with a definitely relatedgovernment procurement operation, the U. S.Government thereby incurs no responsibility, nor anyobligation whatsoever; and the fact that the Govern-ment may have formnlated, fTrnished, or in any waysupplied the said drawings, specifications, or otherdata is not to be regarded by implication or other-wise as in any manner licensing the holder or anyother person or corporation, or conveying any rigettsor permission to manufacture, use or sell anypatented invention that may in any way be relatedthereto.

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THE 1 4

15 JUNE 1963 REPORT PR 281-4Q-4

COPY NO. _ 9

(Title Unclassified)

TENSILE AND CREEP-RUPTURE PROPERTIES OF DISILICIDE-COATED UNALLOYED MOLYBDENUM SHEET

AT 2800°, 3000., AND 3200.'F

DDC

DATE 15 June 1963 REPORT PR 281-4Q-4

19

UNCLASS IFI ED

(Title - - Unclassified)

TENSILE AND CREEP-RUPTURE PROPERTIES OF DISILICIDE-COATED UNALLOYED MOLYBDENUM SHEET

AT 2800', 30000, AND 3200 F

Contract AF 33(657)-8706

Project 281

PREPARED BY APPR

'A. S. Rabenbteine M. J1 Albom, ManagerMaterials and Process Section

CHECKED BY

J. W. ChambersUNCLASSIFIED

THE *

VAN NUYS, CALIFORNIA

UNCLASS IFIED VAN NUYS, CALIFORNIA ,,o, PR 281-4L0-4

CONTENTS

Section Page

I SUMMARY ............................................... .

II INTRODUCTION ............ ........................... . i...1

III TEST PROCEDURES ............. ......................... . i...1

A. Preparation of Test Specimens ......... ................. 1B.'* Test Equipment .............. ..................... . i...1C., Temperature Measurement ............... .................. 2

IV TEST RESULTS .................... .......................... 2

V DISCUSSION ..................... ............................ 2

VI CONCLUSIONS ............. ............................... 3

DISTRIBUTION .................. .................... ... 12

UNCLASSIFIED

UNCLASSIFIED VAN NUYS,, AL,,ONIA REORT PR 28T.4Q-4

TABLES

Table Page

I Tensile Properties of Disilicide-Coated Unalloyed MolybdenumSheet ............ ........... ............................ 4

II Creep-Rupture Properties of Disilicide-Coated Unalloyed MolybdenumSheet ............. ..... ..................................

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UNCLASSIFI ED VAN NUYS. CALIFORNIA REPoRT PR 28T-)F-4

ILLUSTRATIONS

Figure Page

1. Marquardt Elevated T5mperature Test Machine TM-1A ..... ......... 6

2. Creep-Rupture Properties of Disilicide-Coated UnalloyedMolybdenum at 2800°F ...... ... .......................... 7

3. Creep-Rupture Properties of Disilicide-Coated UnalloyedMolybdenum at 3000°F .............. ... ....................... 8

4. Creep-Rupture Properties of Disilicide-Coated UnalloyedMolybdenum at 3200°F .............. ... ....................... 9

5. Creep-Rupture Properties of Disilicide-Coated UnalloyedMolybdenum ..... ....... ..... . . . ........ ........... 10

6. Two Percent Creep Properties of Disilicide-Coated UnalloyedMolybdentun . . . . . . .. ... .... . . .... ............. ......... 11

UNCLASSIFIED - -

I*fv PR 28l-4Q-4UCLAS S I F I ED PR"°-'"QlI

UNCLASSIFIED VAN NUYS, CALIFORNIAREOT

I. SUMMARY

Tensile and creep-rupture properties were obtained for disilicide-coated unalloyed molybdenum sheet (0.040 inch) at 28000, 30000, and 3200'F. Thebase metal substrate was disilicide coated approximately 0.0025-inch thick. Atwo-color Shawmeter (optical pyrometer) provided an accurate and convenient methodto determine and to control test temperatures on the coated specimens. The ulti-mate tensile strengths at 28000, 30000, and 3200'F were approximately 12, 11, and10 Ksi, respectively. The stress values to cause 2 percent creep in 2 hours at28000, 30000, and 3200*F were 4,3, 3.8, and 3.0 Ksi.

II. INTRODUCTION

In aerospace applications, almost all refractory metal'usage is in anoxidizing environment. One of the most widely used refractory metals is commer-cially pure molybdenum, and the coating system that has found the greatest favorfor protection against oxidationis the disilicide coating.

The mechanical properties of commercially pure molybdenum have beenwell documented. However, as the disilicide coating is a diffusion type, the ef-fect of such a protective system on the mechanical properties of the bare metal isof-great importance.

The program reported herein was conducted to determine the tensile andcreep-rupture properties of disilicide-coated unalloyed molybdenum sheet (0.040inch) at 2800°, 30000, and 3200°F.'

III. TEST PROCEDURES

A. Preparation of Test Specimens

Tensile and creep-rupture test specimens were prepared from 0.040-inch thick unalloyed molybdenum,(AMS 7800).. A finish of 32 rms or better was givento all surfaces. Special consideration was given to the edge radius in the reducedsection of the specimens. The specimens were lightly vapor-honed, degreased, andthen disilicide coated approximately'0.0025 inch thick. After coating, the speci-mens were oxidation tested in air at 2500'F for five minutes. None of the speci-mens failed in this test.

B. Test Equipment

Tests were conducted on the Marquardt Elevated Temperature TestMachine (Figure 1) in a still air atmosphere. Specimens were self-resistance-heated to test temperature and held at temperature for five minutes prior to load-ing. Strain rates were controlled using a calibrated load cell. A Marquardt-developed electromechanical extensometer was used for strain measurement. Deadweight loading was used during the creep tests.

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UNCLAS I FIAE PR 281-4Q-4LJNCLAS S IF I ED VAN NUYS, CALIFORNIA RPR R2l)~-

C. Temperature Measurement

A two-color Shawmeter (optical pyrometer) was used to measure testtemperatures. The Shawmeter was calibrated against a special battery-operatedcalibration unit using a standard tungsten filament calibration lamp (G.E.) beforeeach test, and at approximately one-hour intervals during the creep tests.

IV. TEST RESULTS

Tensile properties of disilicide-coated unalloyed molybdenum sheet ob-tained at test temperatures of 28000, 30000, and 3200'F are presented in Table I.Creep-rupture properties obtained at 28000, 30000, and 3200°F are presented inTable II. These data are shown graphically in Figures 2 through 6.

The ultimate tensile strengths at 28Q00 , 30000, and 3200°F were ap-proximately 12, 11, and 10 Ksi, respectively. Yield strengths were approximately8, 7, and 6 Ksi. The stress values to cause rupture in 2 hours at 28000, 30000,and 3200'F were 4.17, 3.7, and 3.15 Ksi, respectively. The stress values to cause2 percent creep in 2 hours were 4.3, 3.8, and 3.0 Ksi.

V. DISCUSSION

Tensile and creep-rupture testing of the disilicide-coated molybdenumpresented special problems in the area of high temperature measurement. With un-coated specimens, temperature can be measured up to 5000'F in an inert atmosphereby the use of thermocouples. However, thermocouples cannot be directly welded toa coated specimen (as is the procedure for testing specimens of bare metal.)

The Shawmeter was utilized in this program because it is not dependenton known emittance values of the disilicide coating as is required in the use ofthe Micro-Optical Pyrometer (one-color pyrometer). The exact emittance of thecoated molybdenum was unknown, and the emittance varied with time at the elevatedtest temperature investigated.

Prior to tensile and creep-rupture testing, the following steps weretaken to improve the Shawmeter technique:

1. The addition of a meter to allow incident energy input to be ad-justed to the same value for all test and calibration readings.

2. A table of tungsten calibration lamp and color temperatures wasprogrammed for IBM and run off to obtain a compilation of bright-ness, color, and contrast values at 10 intervals over the testtemperature range.

3. A special battery-operated calibration unit utilizing a standardtungsten filameht calibration lamp (G.E.) was used to calibratethe Shawmeter.

UNGLAS-2-ILD 2

UNCLASIFIDEoT PR 28l-4Q-4UNCLASSIFI EDVAN NUYS, CALFORNIA.

4. The Shawmeter was calibrated at one-hour intervals during thetest runs. The maximum drift in one hour was no more than +20 0 F.

5. During test runs, the Shawmeter was positioned far enough awayfrom the heated test specimen to insure that the viewing windowdid not become coated.

VI. CONCLUSIONS

The scatter of both the tensile and creep data was quite small, indi-cating that the raw material properties were uniform. In addition, the coatingprocess was reproducible, and temperature control was uniform.

The Shawmeter was capable of accurate temperature measurements on thedisilicide-coated molybdenum specimens within +50' at 3200'F.

The optical pyrometer cannot be used on coatings for long periods oftime unless. the effect of time on the coating's emissivity is known.

UNCL ASSIFIED - 3 -

UNCLASSIFIED VAN NUYS, C*AWLIPOEwNIA REPORT PR 281-4Q-4-i

TABLE I

TENSILE PROPERTIES OF DISILICIDE-COATEDUNALIDYED MOLYBDENUM SHEET

Test Conditions

Sheet thickness = 0.040 inchMachine Marquardt ETTMStraih rates = O.OOlin./in./sec to yield

0.01 in./in./sec to rupture.

Hold time = 5 minutesTemperature indicator = ShawmeterTest atmosphere Air'

Test 0.2% Yield Ultimate Tensile Elongation in Young'sSpecimen Temperature Strength Strength' 1 inch Mogulus

Number (OF) (Ksi) (Ksi) (1) (10 Psi)

831H 2800 7.5 12.3 4.0 --

832H 2800 8.2 11.8 4.2 .. 8.0

829H 3000 7.5 11.0 9.9 . 5.7826H 3000 6.8 10.7 9.6 5.1

, 824H 3000 7.4 12.3 4.0 5.0

858H 3200 6.2 10.0 9.6 --

859H 3200 6.1 10.0. 11.5 4.8860H. 3200 6.3 10.4 11.8 --

UNCLASSIFIED -4 -

UNCLAS SI FIED VAN NUYS, CALIFORNIA REPORT PR 281J4Q-4

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CREEP-RUPTURE PROPERTIES

OF DI SILICIDE-COATED UNALLOYED MOLYBDENUM

5.0

4.0

Ln 3.0Lu NOTES

ILl

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zlrquardll_ _ _

UNCLASS I F I ED VAN NUYS, CALIFORNIA REPORT R 2-4•-4

DISTRIBUTION

Copy No. Transmitted to

1. Syracuse University Research InstituteDepartment of Chemical Eng. & MetallurgySyracuse 10, N. Y.Attn.: Dr. Volker Weiss

2. Syracuse University Research InstituteBox 145, University StationSyracuse 10, N. Y.Attn.: Dr. C. S. Grove, Jr.

Defense Metals Information CenterBattelle Memorial Institute505 King AvenueColumbus 1, Ohio

4, 5. CommanderAeronautical Systems DivisionDirectorate of Materials & ProcessesWright-Patterson AFB, OhioAttn.: ASRCEM-l

6. Thermophysical Properties Research CenterSchool of Mechanical EngineeringLafayette, IndianaAttn.: Dr. Y. S. Touloukian

7. Plastec

Picatinny ArsenalDover, New Jersey

8. Belfour Engineering Co.Suttons Bay, MichiganAttn.: Albert J. Belfour

9. Hughes Aircraft CompanyFlorence and Teale StreetsCulver City, CaliforniaAttn.: E. M. Wallace, Library Services

10. CommanderAeronautical Systems DivisionDirectorate of Materials & ProcessesWright-Patterson AFB, OhioAttn.: ASRCEE

UNCLASSIFIED - 12 -

]NI A!; I FVI FD VAN NUYS, CALIFORNIA REPORT PR 281-4Q-4

DISTRIBUTION (Continued)

Copy No. Transmitted to

11 to 20. Armed Services Technical x f0rmation AgencyArlington Hall StationArlington 12, VirginiaAttn.: TIPA

21. Forest Products LaboratoryMadison 5, WisconsinAttn.: Mr. Fred Werren

22. CommanderAeronautical Systems Divisi 0n",_Directorate of Materials ad Processes

Wright-Patterson AFB, OhioAttn.: ASRCEM-I, Library

UNCLASSIFIED 13 -