DISTRIBUTED BY: National Technical Information Service U. S. … · General Motors Corporation Prepared for: Air Force Aero Propulsion Laboratory December 1972 DISTRIBUTED BY: National

AD-753 417

L.IGHTWEIGHT GEARBOX DEVELOPMENT FORPROPELLER GEARBOX SYSTEMS APPLICATIONSPOTENTIAL COATINGOS FOR TITANIUM ALLOYGEARS

Richard A. Hirsch

General Motors Corporation

Prepared for:

Air Force Aero Propulsion Laboratory

December 1972

DISTRIBUTED BY:

National Technical Information ServiceU. S. DEPARTMENT OF COMMERCE5285 Port Royal Road, Springfield Va. 22151

AFAPL-TR-72-90

LIGHTWEIGHT GEARBOX DEVELOPMENT

FOR PROPELLER GEAUbOX SYSTEM APPLICATIONS

POTENTIAL COATINGS FOR

TITANIUM ALLOY GEARS

R. A. Hirsch

Detroit Diesel Allison Division

LO• General Motors Corporation

Indianapolis Operations

TECHNICAL REPORT AFAPL-TR-72-90

December 1972

Approved for public release; -r '-)distribution unlimited -

Re0r•cc d by

NATIONAL TECHNICALINFORMATION SERVICE -....

U S Dopato~t c'•n C _,,mn-,.* A 22151

Air Force Aero Propulsion LaboratoryAir Force Systems Command

Wright-Patterson Air Force Base, Ohio

NOTICE

When Government drawings, specifications, or other data are used

for any purpose other than in connection with a definitely related Govern-

ment procurement operation, the United States Government thereby incurs

no responsibility nor any obligation whatsoever; and the fact that the

government may have formulated, furnished, or in any way supplied the

said drawings, specifications, or other data, is not to be regarded by

implication or otherwise as in any manner licensing the holder or any

other person or corporation, or conveying any rights or permission to

manufacture, use, or sell any patented invention that may in any way berelated thereto.

Copies of this report should not be returned unless return is required

by security considerations, contractual obligations, or notice on a specific

document.

UNCLASSIFIED-ISpcuuit Classification

DOCUMENT CONTROL DATA - R & DISecurity classification of title, body of abstract and indexing annotetior" must be entered when the overall report is clarsllled)

SORIGINATING ACTIVITY (Corporate afuthor) 20. REPORT SECUR'TY CLASSIFICATION

DETROIT DIESEL ALLISON DIVISION OF UNCLASSIFIEDGENERAL MOTORS CORPORATION 2b. GRoup

INDIANAPOLIS, INDIANA 462063 REPORT TITLE

LIGHTWEIGHT GEARBOX DEVELOPMENT FOR PROPELLER GEARBOXAPPLICATIONS POTENTIAL COATINGS FOR TITANIUM ALLOY GEARS

4 OESCRIPTIVE NO rES (T7v e- of report and inclusive dates)

Final ReportS AU THORtSI (FIset neme. middle Initial, last name)

Richard A. Hirsch

6 REPORT DATE 78. TOTAL NO OF P AJES 7b. NO. or REFS

December 1972 . Oy 17 None. CONTRACT OR GRANT NO 90- ORIG!9*ATORQS REPORT NUIABERIS1

F33615-70-C- 1383b. PROJECT NO DDA EDR 7326

306636 9b. OTHER REPORT NOISI (Any other numbers Mlat may be asslined

this erport)

d.

Itn O'STRIOUTION STATEMAENT

11 SU*PLEMENTARY NOTFS 112 SPONSORING UIL! TA"Y ACT!VITY

D034086 _ *,$' 0it-,I.s•4..;. lAir Force Aero Propulsion LaboratoryJ Air Force Systems Command

13 ABSTRACT • Wright-Patterson Air Force Base, Ohio131 AA•ST•AC T

The objective of this program is to develop the capability of titanium gears to sustain 126 millionrepetitive stress cycles at a surface contact stress of 132, 000 psi (based on steel modulus of elas-ticity. The achievement of this goal will make titanium gears significantly attractive for the 1975time period.Optimum titanium material composition was selected to provide desirable strength properties undcompatibility to the selected surface coating !system. Plated surface coatings, bonding techniques,heat treat processes, and surface lubrication coatings were investigated to provide an optimum sys-tem which would withstand the scheduled test requirements. Iron-plated coatings which were diffu-sion bondect to the titanium core and then cartonitrided to provide surface hardness were selected asthe most promising system.Test specimens were fabricated and tested or, the Tribometer to evaluate the surface durability andresistance to scoring. Additional specimens were tested on :he threo-ball-and-cone rigs to evaluatepitting fatigue life under high Hertzian rolling contact loads.Three s(-ts of test gears were designed and manufactured utilizing the dev2loped system. Experi-mental evaluation of the test gears estanlished their 107 cycle surface contact fatigue strength(baIsed on steel modulus of elasticity) at: Phase 1 96.000 psi Phase II 120, 000 psi Phase III152, 000 pbi.Secondary goals of oil starvation, oil contamination, and full-scale endurance tests were not accom-plished in order that process development could be continued to improve the small scale gear strength.

DD , O 1473 ]T 6c, VNCLASSLFLLI)

UNCLASSIFIEDSecurity Classification

24 LINK A -INK S LIIC CKEY WODOs I - i

ROLE WT ROLE WT ROLE WT

Titanium gears

Coated titanium gears

Aircraft gearing

Iron-plated titanium gears

Lightweight gearing applications

Diffusion bonding

UNC LASSIFIEDSe'urIt' CIa-irgcalon

AFAPL-TR-72-90

LIGHTWEIGHT GEARBOX DEVELOPMENT

FOR PROPELLER GEARBOX SYSTEM APPLICATIONS

POTENTIAL COATINGS FOR

TITANIUM ALLOY GEARS

R. A. Hirsch

Detroit Diesel Allison Division

General Motor! Corporation

Indianapolis Operations

TECHNICAL REPORT AFAPL-TR-72-90

IDecember 1972

Approved for public release;distribution unlimited


Air Force Systems CommandWright-Patterson Air Force Base, Ohio

_z-

FOREWORD

This final technical report was prepared by Detroit Diesel Allison Division, (DDA), of General

Motors Corporation, Indianapolis. Indiana, under USAF Contract F33615-?G-C-1383. The

contract was initiated under Project No. 3066, Task No. 306612. The contract was adm..•r'i-

stered by the Air Force Aero Propulsion Laboratory, Air Force Systems Command, Wright-

Patterson Air Force Base, Ohio. Mr. M. P. Wannemacher, (AFAPL/TBP) was Project

Engineer for the Air Force.

Mr. R. A. Hirsch, Section Chief, Mechanical Technologies, was Program Manager at DDA

for the project. Acknowledgment is made to the many contributors within DDA, especially

J. A. Burger, J. F. Kildsig, L. W. McBride, Q. 0. Shockley, P. L. Colcord, F. K. Lea,

and M. R. Chaplin.

This report covers the development of coated titanium gears from February 2, 1970 to

September 1, 1972, and is assigned DDA supplementary report number EDR 7326.

This report was submitted by the author December 1972. Publicition of this report do not

constitute Air Force approval oi the reports findings or conclusions. It is publishd crnly for

the exchange and stimulation of ideas.

Ernest C. Simp/nDirector

Turbine Engine Divi.ion


II

ABSTRACT

The objective of this program was to develop the capability of titanium geax. to sustain 126

million repetitive stress cycles at a surface contact stress of 132, 000 psi (based on steel

modulus of elasticity). The achievement of this goal will make titanium gears significantly

atu'z!cive for the 1H75 time period.

Optimum t.tanium material composition was selected to provide dcsirable strength properdies

an() compatibility to the selected surface coating system. Plated surface coatings, bonding

techniques, heat treat processes, and surface lubrication coatings were investigated to pro-

vide an optimum system which wc•-d withstand the scheduled test requirements. Iron-plated

coatings which were diffusion bonded to the titanium core and then carl~onitrided to provide

surface hardness were selected as the most promising :'ystem.

Test specimens were fabricated and tested on the Tribometer to evaluate the surface durab'.lity

and resistance to -coring. Additional specimens were tested on the thrce-ball-ano-cone rigs

to evaluate pitting fatigue life under high Ilertzian rolling contact loads.

Three sets of test gears were designed and manufactured utilizing the developed system. Ex-

periment,-d evaluation of the test gears established their 107 cycle surface contact fatigue

strength (based on ,:teel modulus of elasticity) at:

* 0 Phase I 96, 000 psi

0 Phase H 120, 000 psi

0 Phase 111 152, 000 psi

Secondary goals of oil starvition, oil contamination, and full-scale endurance tests were not

accomplished in order th-.t process development could be continued to improve tYhe small-scale

gear strength.r

!

II

TABLE OF CONTENTS

Section Title Page

Introduction ................... ................................. 1

1 Technical Discussion ................ ............................ 3

Titanium Alloy Selection .............. ........................ 3

Hard Surface Coating ............ .......................... 7

Electroless Nick.A (GI Nichen,) C0mating ..... .............

Electrodeposited Iron-Nickel Coating ....... ............... 9

Electrodepositad Iron Coatings ........... .................. 9

Hard Surface Coat Bonding ............ ....................... 18

Heat Treatment .......... ............................. .... 23

Nitride Process ................ .......................... 23

Carburizing Process ............. ........................ 24

Carbonitriding Process ............................. .... 24

Treatment Process ....... ......................... .... 26

Surface Lubricant Coatings ............ ....................... 31

Dow-Cornir- !-3M43 (AFMiL-41) ........ .................. 33

Silver + Telluride Ag-N-bTe2. ......... .................... 34

Teflon + Molybdenum Disulfide (Teflon- loS2 ) ............... 34

III Gear Design ................ .................................. 35

Phase I Gear Design ........ ........................... ... 35

Phase 1I and Il Gear Design ............ ...................... 36

IV Gear 'Manufac!ure ...... .............................. 43

V Testirng!Analysis .......... ............................... .... 49

Triborneter Tests ............. ............................. 49

Electroless Nickel (Nichem) Ward Coating ................... 51

Carbonitrided Iron and Iron Nickel Hard Coating ............ .1

STriborneter Test Conclusions ........... ................... 52

Three- Ball- ,.nd-Cone Tests ............. ...................... 56

Test Pa-ameters ......... .......................... ... 56

Oil Starvation Testing ............ ....................... 60

Three-Ball-And-Cone Test Conclusions ....... .............. 60

R. R. ".Wore Test'.. ................................... i. 2

R. R. Moor'e Test Conclusions ........... .................. 65

Crushing Tests .............. ............................. 65

('ru.l!ing 7Tst :coýclusions ........ .................... 65

V , Preceding gage blank

w

Section Title-_ _. Page_ _

Ryder Gear ............................ 66

Test Parameters................................... 68rtst Gear Load Schedules ........ ..................... 68Test Gear Inspection ............. . . . . ... ........

Ryder Gear Test Data.................................. 69MlAllugIy Analysis ....... ........................ .... 69

Gear Test Su- ...mary ..................................... 79

VI Conclusions and Reczrmu:endations :33...................................................... 3

Appendix 1. Comp.ter Output of the TIDA Gear Design Program ...... .... 85Appendix Hi. Ryder Gear Test Inspection Data Sheets For i.Hrd Coated,

Small-Scaf.• Titanium Gears..........................

Appendix ILL Gear Manuiacture Process Routing .................. 105

|vi

LIST OF ILLUSTRATIONS

Figure Title Page

1 Comparison of minimum tensile ultimate strengths at various

temperatures .................................. 5

2 Comparison -.f rm'inimum 0. 2% yield strengths at various temperatures . 5

3 Comparison of 107 fatigue strength ............ ..................... 6

4 Fatigue -4 rength vs section thickness and hardenability . .......... 6

5 Iron-nickel alloy segregation in tooth flank ........ ................. 9

6 Small volume plating rank ............ ........................... 10

7 Large volume plating tat;k ............. ......................... 11

8 •ijxi.U-ry anode plating fixtur..: .............................. ... 12

9 Silicone '-ubucr plating mask ........ ......................... .... 13

10 Micarta mask with gear tooth form spaces ............................ 14

11 Mask with z 1justable slot sizes ............ ....................... 15

12 Gear plated in adjustable slo'ted mask (0. 01-in. plate thickness) ..... 15

13 Fifth plate mask ...... ....... .............................. ... 16

14 Gear plated in fifth mask (0. 015-in, plate thickness) ...... ............ 16

15 Optimum plating mask .......... ........................... .... 17

16 Final optimum plated gear (0. 018-in. min plate thickness) .............. 17

17 Shielded plating anode .............. ............................. 18

16 Plated titanium diffusion test specimens ....................... . . 19

19 Vacuum diffusion zone ....... .............................. .... 21

20 Electroi, -nicroprobe study of iron coating and titanium . ......... 22

21 Electron micruy-obe study of iron-nickel coat;Ing and titanium ....... ..... 22

22 Iron coating structurt. with Tufftride heat treatment ...... ............ 24

23 Typical carbonitride of iron ,.,• titanium ...... .................. .... 26

24 Heat treatment hardness gradient ............ ...................... 27

25 Bending stress geometry ............. ........................... 36

26 Phase I wide gear design ............. ........................... 36

27 Phase I narrow gear design ....... ......................... .... 37

28 Subsurface stress distribution . . ...................... 38

29 Phast, 11 narrow gear design ....... .................... ...... ... 39

30 Phase II wide gear design .............. .......................... .39

31 A;arvufacture of gear tooth profile ............ ...................... 43

32 'ypical gear inspection charts ............. ........................ 46

33 Phase I finished gear set ........ ........................... ... 47

34 Phase III finished gear set ....... .......................... .... 47

35 Tribometer test rig and test parameters ......... .................. 49

36 Tribometer rotating specimen ............. ........................ 50

vii

Figure Title Page

37 Tribometer stationary platen specimen ........ ................... 50

38 Typical Tribometer test cylinder and platen ......... ................ 51

39 Typical failure Fe and Fe-Ni coating with electroless Ni bond medium . 52

40 Results of Tribometer testing of bare finish ground electroless Ni . . .. 53

41 Results of Tribometer testing of carbonitrided Fe + AFML (DC1-3943) . 5442 Summary of Tribometer friction testing ........ .................... 55

43 Three-ball-and-cone test rigs ...... ......................... .... 56

44 Three-ball-and-cone fatigue tester schematic ...... ................. 56

45 Three-ball-and-cone rig test specimens .. .... ................ .... 57

46 Three-ball-and-cone teat specimens ......... ...................... 58

47 Three-ball-and-cone test summary ...... ..................... .... 58

48 Typical cone specimen failure ...... ......................... .... 58

49 Typical microsection of pitting fatigue failure .................. .... 62

50 R. R. Moore test specimen ............ ......................... 63

51 R. R. Moore fatigue test summary ...... ..................... .... 63

62 R. R. Moore test specimens ............ ........................ 64

53 Phi,, :e I type gear: 36 teeth, hard coated with Fe-Ni alloy .............. 66

54 Phase 1i.11 typc gear: 21 teeth, hard coated with Fe ...... .......... 67

55 Ryder-ERDCO gea.' testei -.-:th antifriction gear head and CRC oil cart 68

56 Wide gear tooth fracture ........... ........................... 71

57 Fractured gear teeth induced by fatigue failh,re ............... 71

58 Phase II. 1 contact pattern of mislocated geac... ................. ... 72

59 Phase I. 2 gear tooth damage ................................... .. 73

60 Tooth plate thickness macro section..., . ..................... ..... 73

61 Photomicrograph of diffusion zone cracking. ,................. 74

62 Phase II. 3 gear teeth damage ....... ........................ .... 75

63 View of gear tab lock failure ......... ............................ 75

64 Phase III. 1 and . 2 gear damage by loose retaining nut ............. .... 76

65 Phase III. 3 test gear damage . ................... ........ .. 76

66 Phase III plating line defect ..................................... 77

67 Gear web failure .... .. ....................... 77

68 Case condition adjacent +o failure ........................... 78

69 Phase III. 5 test gear failure .................................... 78

70 Photomicrugraphs typical of the case strLuture. ...... ............... 79

71 S/N test schedule. ............. .. ............................. 80

viii

LIST OF TABLES

Table Title Page

I Composition of titanium alloys .............. ........................ 4

H Diffusion depth, inches, of iron and iron-nickel in Ti 6AI-2Sn-4Zr-6Mo . . 20

IL! Tensile properties after vacuum diffusion ......... .................. 21

!V Carbonitride surface hardness-depth ........... .................... 25

or Effects of low temperature treatment on surface hardness 15N- ...... 27

VI i•15N hardness values of specimens given final high-temperature temper

treatment of 450.F ............. ............................ .... 28

V_!! R 15- hardness values o~f specimens given final high-temperature temper

treatment of 550*F ............... ............................ 29

VIII R 15 , hardness values of specimens given final high-temperature temper

treatment of 650, 750, ant: 500*F.. ............................. 30

DX R 15N hardness values of specimens given final high-tomperature temper

treatment of 500°F ............... ........................... 31

X Tensile properties after simulated 600OF carbonitride and 350 to 950 0 F

temper ................. ................................... 32

Xi Tenitile properties after simulated 1550°F carbonitride and 350 to 950*F

temper ................ .................................... 33

XII Titanium material properties with 2. 0-2. 25 hr carbonitride cycle ..... 34SXIII Phase I test scheduik -surface stress ........... .................... 37

XIV Phase I test schedule--bending stress ..... ...................... .... 38

XV Phase II and III test schedule--surface stress ..... ............... .... 40

XVI Phase II and Ill test schedule--bending stress ..... ................ .... 41

XVII Phase I, II, and JI- narrow gear process dimensions (in.) ...... .......... 44

XVIII Phase I, II, and III wide gear process dimensions (in.) ..... ............. 45

XLX Summary of Tribometer wear scars ......... ........................ 55

XX Three-ball-and-cone test results iron-nickel alloy .................. ... 59

XXI Three-ball-and-cone test results iron-nickel alloy and iron ..... ......... 60

XXII Three-ball-and-cone test results--electroless nickel ...... ............ 61

XXIII Thermal prcecssing of R. R. Moore plated fatj test specimens ....... 63

XXIV R. R. Moore fatigue test results ......... ... ...... ................. 64

XXV Load schedules for small-scale titanium gears tested in Phase I, I1, and

XXVI Summary of Ryder gear tests conducted on -mnll-scale gears during

Phase I, II, and IIJ .............. ............................. 70

ix (Page x blank)

SYMBOLS

Sc - Calculated hertzian stress, psi

i , p - Poisson's ratio

E - Young's modulus of elasticity, psi

Wt - Tangential load, lb

#t - ?. essure angle at the operating pitch diar'e-ter

Fe - Effective face width, in.

R - Gear pitch radius, in.

R p - Pinion pitch radius, in.

TQ - Torque, lb in.

Sb - Calculated bending stress, psi

Dv - Stress parabola vertex

Fmin - Minimum face width

XHPSTC - X factor calculated from high point of single tooth contact

xi

SECIMON

Future technolocj" has establizher the need to consider the weight savings tha could be achieved

if high strength-to-weigh ra!'i materials could be used in aircraft gear applicatious.. The

a eight advantage and versatility of titanium eStablishes ift as a desirable gear malterial if its

contact su-faces could be conditianed tL withstand the high aint loadmg required for gear teeth.

Prior Military funded projects since 1954 have advanced the potetial of satisfactory opertitOn

of titanium gears up to the operating level of approxfiately 112. 000-psi hertzian contact stress.

Present. hardened steel gears have z comparable stress capability between 180,000 to 242,000

psi at 107 cycles.

Detroit Diesel Allison (DD.A) has completed a 30-month developmerit program La which iron

coated gears were developed and tested on a Ryder gear test rig.. The program was divided

into thret pLa4es with the ccncluning test gears achieving a stress level of !.2, 000-psi hertzia2n

contact stress.

The success of this program presents a technological advancement toward the ultimate goal of

- replacing steel gears with reduced weight components.

:1?

SECTJMr- 1

TEHUND-CAL DRSCL-SSM

TflANIUM ALLOY SEELFýBQN

Pabis!hed iniformatioa related to thte ase oz Uknlzý alliys; as a gea--r -erdrere-aed the iL--

portance 2atd sece~ssity for a soft.-,e 'ce btni~at off a high strength bAs lm. and the oz

systemn. TUt seleu-ton of the til-r-i- ailor had to be eapKiDe --d dewe!o~pen base mtl~-nt

properties ani at the s2=e time the bat tre-Az s reqau-d foe- "bese pr-ope•r•es =asc be

,ompauible with the processing 7aramesers for appling the co•ing system.

T1he design crLeria used for selecting m tiEta-ium gear allay x.-as s'm-iar to the seleetica. process

used for cartmrtzed and/or nit-rided steel gears: since tine r,&uremýe=s for the tiluei ma-

teral sheuld be very similar to th•a of the steel gear =••aer-iL Botii reqamre a hith yield

s -. w-a. good fai--gue i•c to resist cxcessihe ti.

It w-as rreferable that- the tizanium gear cor,ý materia! exhibit a imrde-ss off RC34 minimum to

reduce the hardness gradieu between coatmng a•. core and to prese= 2 core rel-ioaýhip, sut -

lar to that of steel gears.

T.he r.itanium material u-as required to have good hzrdenaiihtV- and prov-ide adequate Sreng.-

for coating support. regardless of section size.

The proposed surfzce hardening procedure and op.ur.urn core propervi de-elopment tempera-

ture should be compatible.

The ability of the alloy to accept the coating was believed to be of paraum-ount importance; how-

ever, m the selection of a titanium allov there appeared to be no great Jifference in coatability

of the materials considered. Other properties that cou!d influence material selection are

density, modulus of elasticity, Poisson's ratio, and thermal conductivity.

After considering the basic requirements for a titanijm gear material, it Lecomes apparent

that the alloys closest to meeting these requirements are the high strength alpha-beta titanium

alloys such as:

* Ti 6A1-4V (AMS-4928) 0 Ti 6A1-2Sn-4Zr-6Mo

* Ti 6A1-6V-2.Sn (AMS-4971) * Ti 6AI-5Zr-4Mo-lCu-0.2.Si (IMI Ti 700)(EMS-59030)

Composition of these allw.vs is shown in Table I.

3

Ta•ina L

______= Ti C-2-4-64" TR 6-44 TS S!-2 m '*4,

Var- 3.50-4.5-0 5. 0-6.C cc

0 ~e . ... 0._ax-0.O'" -. -i_,° 0

G-rro ~ 04ira 0- .0 Omax 10.05 =rax 0.. 15 max,

o.vge~ i0 no-- 0. 2"0 =2M 0.. 20 mTr: -

ir ogen 0.. 002 Max 0- 05 ='ZZ 0. 04 En --

pwda-ogean O.0.05z-a 0- 0! 25 n-3 0- G!5m 0..OIN3z

Other ele•-•ens --- O. --0 --ax 0. 40 m-- - - -

TfRi=femainder Ht-ma,-er Re- er -Icmder

tTi 6Al-Z2 S-4AZr-6l7o

tTi 6AI-SZr-4Mo- lCu-0- 251

•, ~(l..1 700) (E•,1•-5.•030)

1These materials exhibited ultimate strernths of i40, 000 .o 160, 000 psi in the solution :reated

and 190, 000 to 200, 000 in the -Aged condision.

The coatability of the listed alloys is essentilly the sa,. howeier, the compatibility of the

base metal heat treatment and coatin, heat treatment can vary- and is of great imp<, lance. If

the ahoy" is to be used in the solutioen hcat treated and aged (ondition, then the greatest flexibilitv

and strength response can be achieved with the alloys that a -e capable of being ai;--cooled from

the solution treating temperature. This would allow a marriage of the solution heat treatment

and coating thermal treatment.-i without the need for an integral rapid qr:ench facility, It also

minimized distortion and residual stresses caused by rapid quenching. With such a material a

selected coating treatment in the range of 1550 to 1650'F would also serve as the solution treat-

ment of the titanium alloy: any treatment below I l00', i.,e., ritriding. could be done within the

aging treatment or after the aginz treatment.

4

A ca=Prism 'o te~sik pspe!¶iiks as s&DUM Fie~rws I = 2 ufci shw tr;ý th& c.- - led

z alloys fail saso 2: respect~abe stre~g~ raege The aan-co d Ta 2---d42b-63ýr_ _coaled lIM! 7-TOO0 devetfla aDtine3L-ehs of 175. ~O PSIL or abon X.-

tm the falz~e=& properrt is sb" = Figmm- 3 =idzc-- tham e s lc- iztr dnfft-.e=, i*

the fative smerl of the wxEf_ q~r_--tbd Zd Oxr-CM'kd Tt aa~~4Z-h d fLUI Tz 7W_

As sbs4 lot of thes 2alr ?cate h~.I iO3er 1=!Voe SttCP: ftR. Tr. 9A-4Vi

* ~Ti ~-~~

qEsa UBC

Figuire 1. Comparison of minimm tensiie ultima e *rengths at rarious tempe-ratures..

4 a4-

All 3llavE are in the solution tzIIT

treated'and aged condition- 11.

M36- 3

Figure 2. Comparison of niinimum 0. V, yield strengths at various temperatures.

FuCcm 4 gbv" t;- -- le-i2i I SCMCOM2s reialie to Sectim tbkýs Z~~x&DdT

2=6 W. Ti Ts are the bký; the Water-*=Xr.ýt1d =atra WO~ re h B=

also ~±~i~ ~ ~z~a~re_ The Basmer swn'f~r ~ztS

Ls f=U- Cqf v'w marlutil ac-Bmcd br&- wtm~ 2--d~r M !f-set

Tý*~~ OtE

,- - +

31D --

CI M

fture~~7 3. -Z--&4of10

fatigue stmrgtb.

1 2

~1E~ ~&I~s-i~7326-5

Figure 4. Fatigue strength vs sectionthickness and hardenability.

~Tue~Eir seirn-=r tb as2 c~waxw at~ti aa=--cmbiei Tt Ir - _ Areter

semmvr4 BiDU Tz -a5 Th* air-c=Oe Tz VJ-25m-4Zr--S3&* -x3= Seý- &w tfs Ctar grom

T' Dba--tj zmsdrr cima±ng pirtw r¶-6ts, L e- . m-rcintme cace &=- ems am

Fe-91

A-I-.Wm __*fm -rswmntwst rt=e etr tPrerun 2#s ofr zhad nor :0~e 6v srrazl aopphd 2C W&u~ o St in * (1 ==& Ls=~ fO inese

Bczd*==; tmic~ess of1-1 MEDs t:-aS pCifie =oS Mxc fm-es. i core oamm~vh =;-ccn tn

0 ~ ~ ~ ~ F -lcrjs ncke (GZNch5n

*~~~~~~~~k Elcrdeoie Brn~mkl(a''nd

S Elcctroiepcs~ted iro Stac..

tt-ýIU Mmre ft -pca fe IA. 4p*m l'

:~terne Outimt -g s5 Mir za k tav stmixal 2**

-- DC mar- j as!c3 5c-!

Loc* Si* , 2zCIiTz- at 2- l !I-~rtg c-to~audw~

= = :"0eS~t tim-neg ev- f~u_- =2:is.. Th5±rA-_ etoa gS C= R:) fa& 4rvoyr :c1.0

* ~ ~ ~ ~ i p r~erove-2~tr.-e:5~'- -a~ :i'tes e.0c- fk_- CrM~-c -. e -t=

~~C all-. ic-oce~sst-e tetst gear :Ocr& Lse d'e-ie5- -n~ -~%s -nf Sion

,o--gor &6ring subseqz-m final opnan ez-al Cc-.

I h~e it.se of z1ass be.Ad pe~eninz Tras Irnplt-entede 10 Induce c es~esarfac42 sqt!s5ss and

:~,r.reduic- e cracking vendenc-. 01 `.e Ncheni plate- 'Glass pe-ening -A~s 5=d i-

sequ',ýv -o tne eievated temperature diffusion cycle (00GOý P- aszuLseouve.t to e-ad-. pi

opera-:on.. Alihou&h glass bead peening mezsurablh reduced the cracking ze=oency, tne condi-

.Ion Lojl-- -A *-e elimarnate-, ;ýecause of thi~s ckr-ditzon. fi~rthzer heý! v-. Xihr':kr p.-Ite de-.elop-

mrent on F-ea7-sWas SUSpe-Ided. FIrtiiermore. in the minital efforts to I-ond iron ad- iron-r.ieke1

e~ectrod~eposits to *hc titaniumn A~lu% test specimens. an elec-roless nickei: ýoalzinr 0. 1 to 0- 2

m.i `-uc' was used. T-he thi-I Nichemn .xa~ings, processetd and vacuum he~at treatedl (as pre'-

-iu.docscrmil. r.*) were lighill fine gril wet blasted and elect rochem icalli activated prior to

imncmrsion ir, tht. ironl and ir(,n-nickel platinz solution,5. TI- s-.stern worked well until the

; -"Fr --- p'r rluure htat treatrfl~cnlis 4,rl rcpid quern hts wecre use-d. NI, thlis time it was !earned

th.-r in# jiffL~sd' \;cerr would not withsliind the iherrmal shorks.

% ... ir=e ofarz tkes=2 o(dt zaqinrw diý !mwt~Ea offcr-w 6 cOS

Ttvx 2=*f= -ce Utvsr __m- Cm -C4 O phte! moz a -- twtz *# eaif t!

fot-_~=~ tw-d am t~~v& gearP~l sw-Em ~wit acý a~ sfi.= tie r_ 5et-r oas e

LE '-~ss ac-o n ta s -== Bt=-, bn~- adm_-t_. C=--% --- 6tm=-s- co:tý ~ I

=LS Of

F~gtre 6. SqmaL Tehme platimg WAr

Reszli!ns of -Ork eDiec ~~ e~-71=4 -,7-ra-o.s gea.r Comfigurairwc-s, ledi to sh cor---lusion-

thtat accem.able unifor= :hick6~~i of iron -. Or lroNM- nickel dt-.osa: Were notr n-aal~e o-.

gear'~~~~~~etb,-- bro I! sOff this e-asion, tnr-e'ý- ifr

technia. ,es for p-Tirý. ipezx wer ere o-ec :s folHOWS:

"* * -se a large sarnk -amere ithe ~na-xe " '--, lc;,-teý z: coddriie d rx.nc-Z ffron the sur-

faccs to0 be plate'd.

"* Use Various n-askirng hxt..,,rt s designezc -!o aid in equ;Alizing the plating distrii~ution over the

gear surfaces.

* 0 Use insolubie- auxilaxa-. anodes located near tne gear root surfaces.

Since plating accc-niplisned instl volu...e plating tank- ha.d de onstratced ansatisfactory,

*throwing power" to plate it-to recessed surface ar~eas of the ge~ar teetih, it was decided to tr-.

a large v-olume tarAk- where the nrode to cathode distance w.ould ierelu:1v.-i: ILrgc in co-mpari-

son to that obtained irn the small volume baths.

The enlarged plating ssic,-, *-o%%:- in iiu orsi of .. 200 :al 1i i:.pr'ryhne lin~ed tank-

with an acid re~i:F*ar~t pumnp anc filter -,nit, Four ih rmos,-ticz.ll\ controikdr electric quartz

irnnt-rsion hea: rs rn;flt~in soij~or *( :rpo rturf ---, thic u.,i, ib cqaipp( V. Iith .,n oscillhding

rod cathode agitatzor zinu ;:impl(, r -ul.t.or-2,O~

rim u.•.-___• T26-9

Fg-ure 7. Large vokmae pbtung taL

T-.e su.face o4• :he sant3m•n is covered '-itffi polyprog_-lere blJJs to reduce evaporati mn and'•r. losses.

The t,•ak was _•.•e,1•i GNIR L-on. Plating Solutio-r. (U. S. P--e.nt 3, 40(4-, 074) which is nominall~y

a-S folJoirs:

Ferrous chloride 465 gmin!

Ferrous iron 205 gm/ I

Dispers--t additive I gm/1

pl1 0.5

Temperature 190OF

Anodes Armro iror,

It wa• believed that the greater anode to cathode distan.ces obtainable in the large tank system

wJ-.ild equalize the plate thickness over the gear surfaces. While there was some small im -

pro% cment as compared to the small tank plated gears, the plating distribution was considered

to be unsatisfactory. A PR (periodic current reversal) control unit was added to the plating

current s. sem and periodic reversal current procedures were tried without any appreciable

improvement in -,ating distribution being noted. It wis hoped that PIN processing would reduce

the excess Ilate from the pitch hne outward while at the same time permitting greater deposi-

lion in the zear root area

II

Auxiliary anode plating feasibilit,' was tested by fabricating a fixture, Figure 8 which provided

the auriliary anoding on a gear segment. Insoluble auxiliary anodes were fabricated from

platinum pins placed parallel to thte root surfaces 1/8 in. from the root surfaces. Addition of

the auxiliary anodes appeare', "o provide additio:nal plate to £he root surfaces and was deemed

sufficiently promising to warra:nt addil ional testing,

By varing the anode to roo- distances, plate depths of 0. 008 to 0. 021 in. were obtained.

Although auxiia,- insoluble anodes were found to be helpful in depositing iron in the gear root

areas, use of the fixture was found to be 'oo difficult to cor.trol. As the plate depth built up,

oae or more of the anodes would short out due to misalignment or more rapid deposition in the

i, medte area causing the whole auxiliary anode unit to malfunction and cease plating in the

r(,,Pt .4rea. For these reasons the use of auxiliary anodes for this application was deemed un-

usable.

At this stag-c cf ;:i iLng development, the difficulty preventing attainment of a satisfact )ry

plated gear w.:.' lack of sufficient plating thickness in uhe root area of the gear. Up ,o this

time all plated gears nad .hown excessive build-up from the pitch line outward whvch resulted

in large nodules at tlie OD o: the gear teeth. While this was occurring tihe gear oot surfaces

were still deficient in pla,!ting tlhckness. Extended plating time, up to 32 hr, i. as of little help,

since the nodules grew larger with little improvement tn root plate thicknes,. It was concluded

tnat the formulation of the large nodules was the principle "eason for the' d, ficio., pl.,, ng thick-

ness being obtained in the root a'ea due to the fact that the nodules were st,, ing to shield and

rob the rest of the gear during the plating cycle. To remedy this situat ion, it was decided to

use the "through-the-window" plating principle.

7326-9

Figure 8. Auxiliary anode f 1iti,•g fxture.

12

Several through-the-window plating masks and fixtures were built and tested. The first one

was fabricated from filled -silicone rubber and was made to fit arid plate a 36 tooth gear. This

mask, Figure 9 was fabricated so that the effective window location, was (entered over the gear

tooth space with 0. 125 in. clearance above th. root surfaces. Plating accompiished with this

mask was more uniform in plate thickness than was obtainable by prior methoas. The plate

depth at the tooth pitch line of 0. 022 in. resulted in a plate depth of 0. 0: in. at the root in a

24 hr plating period.

The second mask was fabricated from Micarta to fit a 21 tooth gear. This mask was designed

similar to the rubber mask except the effective window opening was located with 0. 188 in.

clearance above the root surfaces.

Gears plated with this mask were unsatifactory because most of the plating occurred on the

upper half of the teeth while very little plkte was deposited on the root surfaces. Results of

the test indicated the effective window opening was too far away from the root surface.

The third mask, Figure 10, was fabricated from M'carta with 21 gear tooth form spaces whichprovide 0. 070 in. clearance with the gear teeth. The window openings were again located just

opposite the root fillet area. Plating with this mask was unsuccessful because the clearances

were too close, allowing plating buildup to contact the masi and made it difficult to remove

the gear from the mask.

7326-10Figure 9. Silicone rubber plating mask.

13

-- '

7326-11

Figure 10. Micarta mask with gear tooth form spaces.

The fourth mask was fabricated from Micarta to fit a 21 tooth ge.tr. The mask differed from

the previous ones in that the effective window openings are i~cated beyond the .)D of the gear.

The window slots of this mask were much longer than those of the previous masks. Several

plating runs were made with Lnis mask with the slot openings ranging from full open to very

small openings. The mask side opening vents were also varied in size to determine proper

size necessary to produce the desired web plate thickness. Figure 11 shows this mask and

Figure 12 the optimum gear plated with restricted slot openings with 0. 010-in. plate thickness.

The fifth Micarta mask was fabricated using the design configurations found to be most success-

ful when using the adjustable slot mask.

Figure 13 shows the mask and Figure 14 the optimum gear plated with 0. 015 in. min plate

thickness.

The sixth and final mask which incorporates the optimum features of the earlier development

masks is shown in Figure 15 and the optimum plated rx ask. The final optimum gear with 0. 018

in. min plate thickness is shown in I gure 16.

Platlin procedu, - and parameters were as follows:

1. De, rease

14

r

Sq F

7326-12

Figure 11. Mask with adji.Aable slot sizes.

%. I.

7326-13

Figure 12. Gear plated in adjustable slotted mask (0. 01-in,. plate thickness).

15

7326-14Figure 13. Fifth plate mask.

7326-15

Figure 14. Gear plated in fifth mask (0.015-in. plate thickness).

7326-16

Figure 15. Optimum pLAinig nia A

M36-17

Fig-ure 16. Final optimum plated gear.(0. 018-in. min plate thickness)

X CZV Wrt -- =ds ktt7 =It- Add~ 'ItR 94t~ 7L~r± rB 2,41t~

,xt:ý C=!Wr =

4- FLbie 2r- 6-. 5 toTa i w 2~4 ir Lh±- M== Saea P1Sa-iC 6zi-m sxg C~ivru- yýpe

ofsas s~ow= t-- F:C=e I-

5. Sa~icwvm ag==& ý'i roa~mg a--zd &4ar asdmIBy 2Mt zr =G*etr- Sao== z~tD

EIARD SURIFACE COAJT RONSNNAý

Toe f botn teýard Srnfagec ck~i.= to th ha~s cCM~is~ed of zieiti

ef- a s~r-rike of e! -ctro-sess -dckel Mceru- tre2=eýz) to tR bae tbi- qrtor to pva-L-& =I

R%ýge-ereme ab~ =fficif' Strt=CtB- to l ow ne ~ rýr ease e = ..

be:vhte Li-lasioan of hikerzt~e-~ (L e..- , 150OF or abee an q), sss -of-

DO=d !a.i1 '"eS *e'CancZ o'-~.e co=-ition Was c rnnab Zppartn~t M thet firs. -. f.

So4 rifrb sez O a~nd -E-1-ii -- on pcnit ~ r'~ ~c res we~re

obst-rvem on- arer half the Traibommeter and three-ha~l -cane specieins Thbe faiJu'2-e-s occmurred

prin-cipally duing th ie carb dsriding cycle or t"n C~xenc?: oera-tiw-

Titanin= samples incorpora-ving a -Xichbe-rmm strike tn ro-n-nickel s-Lrface coazing were szeý.cted

zo a v-actumn at 1675 -F temperature for four hocurs. Faiaiof ot '-e bond uinerface revealed

tie diffusion zone to be narrow with- th;e Nich-em a~aem acting as a barri-er to deep diffUsio-n.

Mficroh-ardiness; examination revealled a_ considerable reduction in hardness of the zone as conm -

pared with the base titaniumi. It was recognized that an improirenent migim be obte-in-ed by in-

creasing the dew-h of diffusion penetration since an increase in bohhardness and strength

M36-18

Figure 17. Shielded plating anode.

18

Ub:* an-~ e- 2o f t :adr -- 'ffI&e .rtovpm~r tbt ý=oc ~c± r Sa~i b

t ~c a~be~re

Mf -b-t-i

ce-ng:!,4- fffc- 4-F-igure a8.Plte t otn-u dhe Izwfu fsion ts specmens.

x~~tBan D.e 3, ifk-i

The efereOfdf=MC deI** 'z-s rebted to Mad- t~t3 7-M&S.r-WM-ntierl o- r

Cross-~t ati~~~ a.c~-e :be~t .aniý- rar L' imr, e-t-~e 6amt arie adeZe. -Strio e f-i

erazos ccrte z=Vsren ,ýft ZM=As oe-6 -<me f,- 72??dk Hii4r-]t alkr :zýt *-a=== :tm

Micape~te z- -= ,i~e-'- Mabk s Mae S - i ---- ~-~-i~~Ž

cpc~~a--D cfUSI* sei-mle 2nC:s RW, = of 4~ ff- =n

Cros d-f~sso O--wtT :e mnier-atre ?- Z-- te of)

Coating (%F) 1 3 6Diffusion depthi !:nches

Iron 1700 0.002 --- -- -

16715 0. 002 0. 0025 0. 00351600 0.001 0.002 0.003

1500 0.0005 0.001 0.002

1300 Nil Ni.1 0. 0005

Iron -nickel 1700o 0.002 ---

1675 0.002 0.003 0.004

1600 0.001 0.0025 0.0031500 0.0005 0.001 0.002

1300 Nil Nil 0.0005

20

f

Tau* mm MIL5Zw ~ *~

__.En.. 1S E51.- -" 5 - - 151-. si. - - - E . "s. 1

. SEe!Yc• • u !zOi . a --- E 5 5 3--- ! 2.

15ZO- 3 --- 15-L .5

!52~ .- 0 - - 151-3 14ý 7

U e-e, . £ "..5 --- 70. 5 --- I6.Yield stre=rsh, ksi P38..! --- 162.0 --- 157. 5Elongatzien, 15.3 --- 13.1 --- 15.0

"" -"--11- - -- ---

,. " .• . "* .. V6 :. - ;•-z - -o.- "

-0. - _ *

500)X 500XFe Fe-Ni 50OX

M~6-20Figure 19. Vacuum diffusion zone.

2,

£t.U1-z~wtxk_ 5 cb taw ~z=& £=IIW M L*-tL =Lum Emuthwxt af =u L 1i -Lnta

Iran Aqn 44W Titanium

Figue 20. EkeCtrwa micrqwobie Satu& it UrM emti amd fib-i~

FeNi FeNi

14t-.

~~i f1"2r. Ti Ti

7326-22

Mgn 444X I ron Nickel Titanium

Figure 21. Electron microprobe study of iron-nickel coating and titanium.

IM:M ad~uaiar dev-, c a~~i~w *4= ier mu 5Ufa3ri cionrastt- zore*3w aart1 M& _-vMt ontra CIOMt4 :Mir12.i

Mh~ m._-a'x G N.E.-ar rn-.'M MEX-m of1~ =ek : Wlo~ ~us =Fivt. foo tqaiwrt-4 ThsZC-

-r2.z~rb ie= 10t=UM7 ar BMW'F, b a.r~t sfiAxv ther-~l :~avs ruto ns7i

ZWr.rrede :ahe Crc-rk=4 ~ Qerfc thbe v~E= la~zk. Glas~s bt'eaXd Peenarg W-ts Msted stcb-

seqz-sr :o :_Le krtraa' daf:n Cyrcle (1009F) 2zvd s~-eC- to e2ct+i gmFL

Ahbaa gkzass ibezod eC-aarig !-I. rk'y5dced; the Cra,_CkLag* ze~ei. he cea -

dition coabm __ be elMCd !Btcrzse off thins ca~driow, farzter heý-M Nicheti-i plzate &w-rop-

Mrenz oa ge:r~s -zz_ a. s~n~l.Frt~rtoret, =z t. argissa! effforts to lx~d tr~an 5d iron-=aekel

electrodeiOSILS To thoe ti ;-aint 2!10oý tesz sz caneemS. ý_ electroiess nij-:kel cm-- mag 0- 1 to 0. 2

=il thick was Used. 7Tr.4 tNiI ~Chiti l~ proCteSSsec Z a~o ine~.. tra-atec (aS pre-

vicash- 6described) were lighatl, firne gri: -me, blastee -;aýi lcocci~~ ac-ivaed prior- to

s~erslor ir. 1ne IrO' an-; aroxi-nckel pl-tazng s-lutlanrjs_. T-he s-Lste= worked wc-l;it uil the

htgh~er zenniperature heat tre-ý_mei'ts d rapid quen-ches -vere usfed. r-e -t was learned timt

tle diffused Nichenl would not withstard the thermal shocks.

Earlier work b~- GM Researchi LaJhorztories had deter-nined f;aror-Able processes for the harden-

ing of iron deposits b%> suitable heat treatment, 1)eposiis of iroe.-nickel having good harden-

abilit:. were plated on the regular sections of the Tribornetr and three -ball-and -cone test

specimens- The typilcal irregular sections of gear teeth resulted in rich deposits of nickel to

be deposited' on the gear tooth root areas. AXlthough Phase I gears were processed with iron-

.nckel plating, it was found that thei nickel rich areas did not respond favorably to the heat

treatment process.

I-nase 11 and III gears .ver. i - n plated, therefore, efforts were made to provide opt imumn heat

treatment for the iron plated titanium combination. A review of the heal processes follows.

Nitride Proress

ANtte-mpts to h~jrdfn thc iron platc !.,; nitriding were unsuccessful. Nitriding v~as attempted at

lico to I1!00'1 ..rd with %%trious atmosphere changes, hut suff- 'ant surface h. rdnt-ss was not

a c-om plished.

23

=Cl;1 to (:ade-r- ýardk'= amt retzat-m t.fre ptýQ*-ttw- ;k 5a t

T'zi ~i~rtsar ~e~~tnn. _ ttem-iaZre- to - -'st-* :H&e !Ca~ ~t of !a& care

~ ~.-'--~e~ -- ~~as ptcv'-'- proc:SS Carbriziag pron'lde--

~~i- -! eSe SUM-rM-Me a h -rume~s after - oCcSSi t= = z-e m excess off 1E59W..r.L& Co-e M*04Z 2zk zha ar ocessip -2 Wf~Oct -r --6itora. h.'aZt tft-- stpWE

~V ~ZL~Kh rtd¶=, Ca-Se tacis i- e- , Ca~ixfrEZed LO cc zt1jeX) zar4, :eeoe a

F~ro-=-*~~Lr!rg the ao.'irie process orOm-rded suhstaniz snrowc-nern~ tL' t~te hardn~ess

oftro 'W i~e. ~~i~ !lt as accor-ttis-hed 2t 16506F-. The use of thiis t~rtr

__I-, a~ C-.enci :Povided OctInmam case hardnesz of He 55 or higher. Th,-e I 65Oz F leniperat-are,

h',meyer, o):-Oed L~z~tawe izh the ziiardarn tase aIlo'm; stre:gth pro- eries of th i-wt-we:7e drastilcaiv redu~ced-. Reduct-ion of the tem-peratu!-e to 1550'F proved-, o be nnore compat~ibe

-- J

Mg: n: 5M W.n

42

sith the tiftan and stil provided the necessar? hardants in the case. Following an oil

opewah and ternpoing the iron specimens were 1(c 55 to 57 (microhardness). To establish

eamplew beat treatmenu parameters for boh the ir o -ated case and the titanium alloy core,

the foRlowing beat cycles were evaluate, rith results as shown in Table IV.

The 1550OF12.25 hr cycle was selected to achieve ha-.-. •ing of the complete iron plate without

producing excessive carbon at the iron-titanium inter fa: t. Typical microsections are shown

in Figure~ 23.

T•_e finalized carboitiride proces is as follows:

0 Pre-eat gears to 500"F

* C-2rbonitride at 1550"F/2. 25 hr:

o 35 min- 1. 5 ft 3 propane gas

2.0 ft ammonia

Table IV.

Carbonitride surface hardness-de , h.

Temperature Time Surface hardness Depth

(OF) (hr) ( 1 5N) (in.)

1750 6 89.0

4--

1700 6 .. .

4 89.0

1650 6 90.5

4 90.5

1600 6 90.5 ---

4 91.0 ---

1550 6 88.5 ---

4 90.0 ---

3 91.0 0.017

2.75 91.0 0.016

2.5 91.0 0.016

1550 2.25 91.0 0.015

2.0 89.0 0.010

1.5 89.0 0.0085

0. 75 88.0 0. 007

1500 6 88.5 ---

4 91.5

• 25

RePo •lable coPY-be~st 8

i ./

1.5 hr Mgn 2.0 hr 7326-24bOox

Figure 23. Typical carbonitride of iron on titanium.

9 90 min-1.0 ft 3 propane gas

2. 0 ft 3 ammonia

o 10 min-generator gas

0 Oil quench at 350°F

* Temper at 350 0 F/2 hr

* Air-cool to room temperature

0 Temper at 3500F/2 hr

This process produces the gradient shown in Figure 24.

Temper Process

The effect of temper on the case hardness of iron and iron-nickel is shown in Tables V through

IX. The effect on the core properties is shown in Tables X and XI.

The finalized process used on the final gear sets was the 2. 0-2. 25 hr cycle at 1550'F tempera-

ture followed by two 350°F/2 hr temper cycles. The final properties ace shown in Table XII.

26

5045 - •C ting interface

S40

02 4 6 810 1214 1618 2022 24Depth x 0. 001

326 -25

Figure 24. Heat treatment hardness gradient.

Table V.

Effects of low temperature treatment on surface hardness (H 15N).

Carbonitride cycle Oil quench + Low temp-- i00°Ff/ 1 hr

Temperatare Time 350°oF/1 hr temper plus second 350°F/1 hr temper

(°F) (hr) Fe Fe+Ni Fe Fe+Ni

1700 6 89 83--84 92--93 91--91. 5

4 89 81--83 92--93 90--90.5

1650 6 90--91 87--88 92--92. 5 90--91

4 90--91 83. 5--84 92 90--91

1600 6 90--91 87--88 92--93 91. 5-92

4 90--92 85--86 92--94 90. 5-911550 6 88-89 89 90-91 90

4 90 88.5--89 91--93 90. 5--91.5

1500 6 88-88. 5 87 90 89. 5-90

4 91--92 86.5--87 91--92 90--91

27

Table VI.

R15N hardness values of specimens given final high-

temperature temper ireatment of 450 0F.

Carbonitride cycle Ternp.r time (hr)

Temperature Time 2 4 a 12 16

(OF) (hr) Plating Hardness

1700 6 Fe 92 91 91.5 91 91

1700 4 Fe 92 92 91 91 91

1700 6 Fe-Ni 90. 5 90.5 90 90.5 90

1700 4 Fe-Ni 89.5 89.5 90.5 89 90.5

1650 6 Fe 91 91 91.5 90.5 90

1650 4 Fe 92 91.5 90 90 90.5

1650 6 Fe-Ni 90.5 90 90 89.5 89.5

i650 4 Fe-Ni 90 89.5 89. 5 89 89

1600 6 Fe 91 91.5 90 90.5 90.5

1600 4 Fe 92 91.5 91 91 90.5

1600 6 Fe-Ni 90.5 89.5 89.5 89.5 89

1600 4 Fe-Ni 89 89.5 89.5 89. 5 90.5

1550 6 Fe 89.5 89.5 89.5 89.5 89.5

1550 4 Fe 91 90.5 90.5 89.5 90.5

1550 6 Fe-Ni 90 89.5 89.5 89 89.5

1550 4 Fe-Ni 89.5 89.5 89.5 89 89.5

1500 6 Fe 90.5 89.5 89. , F9.5 89.5

1500 4 Fe 9! 92 90.b 90.5 90.5

1500 6 Fe-Ni 88.5 88.5 87 89 88.5

1500 4 Fe-Ni 90 89.5 88 89 89.5

Note: Heat treatment prior to final temper treatment.

Diffuse 1600°F/3 hr + carbonitride cycle as indicated + temper

3500F/1 hr + -100°F/1 hr +350°F/1 hr.

28

Table VII.

R 15N hardness values of specimens given final high-

temperature temper treatment of 550*F.

Carbonitride cycle Temper time (hr)

Temperature Time 2 4 8

(OF) (hr) Plating Hardness

1700 6 Fe 89 88.5 88.5

1700 4 Fe 88.5 88.5 89

1700 6 Fe-Ni 88 88 87.5

1700 4 Fe-Ni 88 87 87.5

1650 6 Fe 89.5 88 88.5

1650 4 Fe 89.5 88.5 88.5

1650 6 Fe-Ni 88.5 88 86.5

1650 4 Fe-Ni 87.5 88 86.5

1600 6 Fe 89 89 88.,5

1600 4 Fe 89.5 89 88

1600 6 Fe-Ni 87.5 88 87.5

1600 4 Fe-Ni 88 88 87.5

1550 6 Fe 88.5 88 87.5

1550 4 Fe 89 89 88

1550 6 Fe-Ni 88 87.5 87

1550 4 Fe-Ni 88.5 88 87.5

1500 6 Fe 87.5 87.5 88

1500 4 Fe 89.5 89.5 89

1500 6 Fe-Ni 86.5 86.5 85.5

1500 4 Fe-Ni 87.5 86.5 86.5


Diffuse 1600°F/3 hr + carbonitride cycle as indicated +

complex temper 350oF/1 hr + -100°F1I hr + 3500F/1 hr.

29

Table V11L


temperature tcmoer treatment of 6500F, 7500F, and 9000F.

Carbonitride cycle Final temper

Temperaturc Time 670°F 750IF 900°F

(OF) (r Plating 2 hr 2 hr I hr

1700 6 Fe 86.5 86.5 79.5

1700 4 Fe 87 86.5 79

1700 6 Fe-Ni V5.5 85 80

1700 4 Fe-Ni 85 85 80.5

1650 6 Fe 86.5 86.5 79.5

1650 4 Fe 87 86 80

1650 6 Fe-Ni 85 85.5 80

1650 4 Fe-Ni 84.5 84 79

1600 6 Fe 86 86 79.5

1600 4 Fe 86.5 86 80

1600 6 Fe-Ni 85 85 77.5

1600 4 Fe-Ni 86 85.5 79.5

1550 6 Fe 85.5 84 78

1550 4 Fe, 86.5 86.5 78

1550 6 'Fe-Ni 85 84.5 79

1550 4 Fe-Ni 85.5 84 77.5

1550 6 Fe 85 83.5 77

1500 4 Fe 86.5 85.5 79

1500 6 Fe-Ni 83.5 83 78

1500 4 Fe-Ni 84.5 83.5 78


Diffuser 1600°F/3 hr + carbonitride cycle as indicated +

complex temper 350°F/1 hr + -100 0F/1 hr + 3500F/1 hr.

30

Table MX.


temperature temper treatment of 5000F.

Carbonitride cycle Temper !ime (hr)

Temperature Time 4 12 18

(0F) (hr) Plating H!-ardness

1700 6 Fe 90 89.5 88.5

1700 4 Fe 91 90 89

1700 6 Fe-Ni 89.5 88.5 88

1700 4 Fe-Ni 89.5 88.5 87.5

1650 6 Fe 90 89.5 88.51650 4 Fe 90.5 8o.5 88

1650 6 Fe-Ni 89.5 88.5 88

1650 4 Fe-Ni 88.5 88 88

1600 6 Fe 90 90 89

1600 4 Fe 90.5 ... ...

1600 6 Fe-Ni 89.5 88.5 87.5

1600 4 Fa-Ni --- 89 88.5


Diffuser 1600°F/3 hr + carbonitride cycle as

indicated + t-rnper 350°F/1 hr + -100 0F/1 hr +

350°F/l hr.

31

I*Ta TPe -X.

Tezsi~ ~ierues ~ersi ate 60SF arbowiridead€ 350 to 950-F tenper.

Only the fi-I temper time Processin

a wd temperaures being Temperantre (OF) Time (hr)

varied as indic2-d.1 1600 3

Slm cool

1600 (Simul2te carbonitride)

Oil Vuench

350 1!-100 !

350 !

Final temper as indicated

Ultimate Yield

Temperature Time strength strength Elongation Reduction of area

(OF) (hr) (ksi) (ksi) r ) (M)

950 2 203.2 184.1 6.5 11.6

750 2 193.8 169.5 11.9 24.8

650 2 168.4 154.8 11.8 25.0

550 12 171.5 163.1 11.0 23.2

550 8 162.6 158.4 14.7 30.0

550 4 151.9 146.7 17.0 30.4

550 2 152.9 144.5 14.6 21.9

500 18 159.5 157.8 16.0 38.5

5 00 12" 157.3 153.6 16.3 30.2

500 8 156.6 154.8 13.5 23.3

500 4 160.4 154.8 14.0 27.0

500 2 150.1 142.5 19.4 23.2

450 24 151.9 148.9 16.8 33.6

450 18 150.9 148.8 19f. 35.6

450 2 149.3 141.9 16.0 21. 7

350 2. 149.9 138.0 17.6 36.2

Notes: Hardness values of specimens below the line meet or exceed R 15N88

minimum value for iron cases.

'Optimum cycle for titanium core strength and iron case hard.**No low temperature treatment (-100°F).

32

Table XL

Tecsile, wopmutes aifte siV~ed 155O'? carban"Ideand 350 to $9S0WF te~per.

00ily the ri~ma temper iti Proe~iesirand temper~eres beiag Tempez-znwe (-F) Tirme V=)

aried as iii-cwed.1550 3

slow cool

1550 5Cimle carboafride)

350 I

-100 1

350 I

Final temper as indica1ed

Ultim2te Yield

Temperature Time stre•gth strength Elong•tion. Reduction of are2(OF) thr) (ksi) (kS) r") (M)

950 2 193.9 167.7 7. 7 8. 7

750 2 162.9 147.9 17.7 32.6

650 2 149.3 142.7 17.4 28-6

550 8 149. 9 143.2 22.1 29.4

550 2 149.3 142.6 16.3 28.2

450 8 149.5 145.3 17.1 37.1

450 2 150.3 145.6 15.7 30.3

z,50 2* 150.3 144.1 18.5 40.0

Note: Hardness values of specimens below the line meet or exceed the R 15N 8 8

minimum value for iron cas-s. Iron-nickel values are 1-2 points less.

*No low temperature treatment (-100 F).

SURFACE LUBRICANT COATINGS

Solid surface lubricant coatings offer a means of preventing sliding friction damage during

periods of limited lubrication or failure of the primary lubrication system. The solid lubri-

cants are of great importance during the original break-in running of near assemblies because

of their ability to shear internally and to move and accommodate to surfact. discrepancies.

Furthermore, they are very adherent to loaded surfaces and have the capacity to retain oil

films which can supply lubrication for appreciable periods of time after failure of an oil supply

system.

33

Tab*e ..JL

3 !-4& 3 45... " .7 E-0.--5O. 256 ..,.'

5 1483 * ,;3 ... 1.•8

r .- M,3 14:_ .

8 ;48..5 W-G. z-.8

Average !4-. 2 143.6 7." 13A

Core !iard-ness (tizaniat) =Rc37_

* Th7-e solid surfiace subrica...ts chossen for tnis programn had de~sr~e zi.eof gooc

prop - ties at ambie-n a- d e!ev•-ed tem:e.:-aures.

Dow Corning 1-34M? L-FML-4!)

This solid surface luhricant is a developrnent of t;h- Air Force .Mlaer:x-4 s Laboratories which

has been licensed to Dow-Corning for manufacture and s Aes. It c.,sz=s of nolyieen.,-

disulfide a.d antirmony trioxide in a resin bince. and was spra% gun applied. r-i&ms of *.he

coating in thicknesses of 0. 5 to 1.0 mil were applied "o Trihometer, three-ball-and-cone,

and Ryder gear test specimens. After spray application, the films were air cured at 350'F

temperature for two hours.

Silver - Niobium Telluride Ag-NbTe2

This solid surface lubricant which is applied electrophoretically is a proprietar'. development

of Detroit )iesel Allison and is the subject of current patent proceedings. The frie particles

of silver and niobium telluride are codeposited at room temperature to a thickness of 0. 2 to

0. 3 mils and require no further treatment.

Teflon + Molybdenum Disulfide (Teflon-MoS 2 )

IFinely divided particles of Teflon dnd molybdenum disulfide are electrophoretic-all., codeposited

to a thickness of 1. 0 to e. 0 mils. This also is a proprietary process of Detroit I),csel Allison

and is a aubje t of current patent proceedings. The coating was tested on Tribometer speci-

mens onl'y. Its properly of extruding under pressure and tniling up outside the lo.td pattcrrn

made it less desira±ble for the three-lhdll-and-cone and |ixder gear surfaces.

34

Th* gears were Y soi to fe.ate cc th Rue gar tster-irtM 3.. 5•- Cemer d1as re

Two sets were desigsttbi are deszemaeed as P"w I apc Mase Ui as 25 x ears..

PHASE I GEAR DE5JG!N

Fse * gears w fa es tid o r .1360 pst bsfZiaM C= SZC*SS hSed Wn. Se*I O Of

elasicizy of 30. 0 X 106 psL. The e iwafii coata1 stu es- fer :xiuasmi _s T_ v.,00 psi based

om a medm~ c 16-5. Jv, 106 PSI- TbC be rtZi-&- Stres eSStU9 ti 9, t d Efo -- ~~-t-.RL

WT RP

whiere:

p=Poisson's rat!.:,

E =Young's modui s.2,f e~asticity n'x IC .si

W, tangential load - 667, lb# pressure angle al pitch di~a- 25 :egrre,

Fe effective face wid _h = 0- 360 in.

RG pitch radius-gt~a.-" = 1. 750 in.

Rp - pitch radius-pinion - 1.750 in.

TQ torque = 1058 lb-in.

The face width of the gears was modified to accom.- c-.':e -. e arxiAl travi it- t e loading mech-

anism of the Ryder z ig, thereby providing full enga-, :nit (.. the r. rr-)w gea- ti , ughout the

operating range of the test schedule.

The tooth thickness of both gears was modified to Mai1 .;i.. bal;.nced bendir-g delection between

the narrow and wide gears. The Lewis stress equatic used *o -aicu'ite th.• n di-., stress

with the load applied at the high point of single tooth co:,' c: (OIV TC) is as follo•.s:

3TQ

D V min XI PSTC

35

x factuor- x: EIpsmT

* Phas-e U a0d 111 Gear Design

ie&= : Pha tse gea =rs Y iso~ sb-m Figue vmar 0wre detn.w riue 8,C-i!i

coTab.t s.ress bse. o. .he s.eel rotiuu of elasticit., of 30. ; , !0• •.d a !'o1sao.w s ---.tio of

0. 30. Th"e 185. 000 :si st.ress is eqii'-i-.ne.• t.o 1-40. 000 •si hertz cont•act for tita•rdu.n. i-i-'. a.mnocal~us of elasticity of cc.5 " 10" and a Posson's .- o of (. 3. "-is st ess ts de.e.o•-d oiaC etlfectiye f -ce tidh of 0. 250 fis&,d tig oa r he a'r " et riga- n- 14, 0 7.

5 piessure angle 40.004Distance over bro 0.1128 mo- pins '-3. of1916 -a.0000

Roof dia 3.263 ±O0.Oi3Pilchdoia'-3.5000Active PrOfile oulside - 3.33301035 diG

I Referenceco-sArc toobh thickness ao PD -0.1 39416 ; O0.001

Dia--fetTC 0.00- to 0.010 .ack0ash with mating geOr on standard centersiv Base ircle dia 3.1720 pn31 0.526

Ro 9 0.5-6

P~hda- 3-50.47

--rc -thickness at P-3.64

Figure 25. Bending stress geometry. Figure 26. Phase I wide gear design.

36

00L9' .1

;lmedie - ~ tie

F•,ure 27. Phase I narzo gear desige..

Tabh XHL

!•.ase I test schedule- surface stress-

Surface stress a- pitch

Test time Total cycles Torque Normal toorth line (psi) (Hz)

(hr) (X 106) (lb-in.) load (1i) Titanium* SteelF

10. 0 8.4 470. 3 296.5 80, 000 105, 928

10.0 16.8 530. 9 334.7 85,000 112,549

10.0 25. 2 595.2 375.3 90,000 113, 169

20.0 42.0 663.2 418.1 95,000 125, 710

20.0 58.8 734.9 463.3 100,000 132,410

20.0 75.6 810. ? 510.8 105,000 139,031

20.0 92.4 889.2 560.6 110,000 145,651

20.0 10M.2 971.9 612.8 115,000 152,272

20.0 126.0 1,058.2 667.2 120,000 158,892

"-Young's modulus--titanium 16. 5 X 106; Poissoi's ratio-titanium 0. 35.

Young's modulus-steel 30.0 / 106: Poisson's ratio-steel 0.30

37

Table XIV.

Pae I teat ,wdi-ed s-ess.

Beaing suvess at Hp c Bending ea- at Ha pTc'

Test time 0i) ToWa pinioe O-.)

04) pinion Gear _______

10.0 8, a2 8,317 0.00041

10.0 9,959 9.389 .00046

10.0 11,165 10,526 0.00052

20.0 12,440 11,728 0.00058

20.0 13,784 12, 995 0.00064

20.0 15, 197 14, 327 0.00071

20.0 16,679 15, 724 0. 00077

20.0 18,230 17, 186 0. 00085

20.0 19,849 18,713 0.00092

HPSTC-h& poin silWje tooth conaci.

20Dwron hertz

!stress150-

50 Senrdingstress

0 5M0 100O M 2000 2500

Normal tooth load-PPI1326-28

Figure 28. Subsurface stress distribution.

3S

D -

W All am~iI are in nhxW.C.02Y4

to- S~C•

26 7 003 0.030S_- 0-02 326-29

Figure 29. Phase H narrow gear design.

Gear todhspaeandsplinetooth to be inline within OdG 5 olin

0 0396 ref

D - etion 0-DNote. All dimensions are in inches.

0.022- 0.012

2. ODO -re! 0.0350.03045 deg 07326-30

Figure 30. Phase U- wide gear design.

31)

To provide a reduced Lewis bending stress of 17, 849 psi, 6.0 diametral pitch, 21 teeth, and

25 degrees pressure angle was selected. The minimum profile contact ratio for this selection

is 1.362. The selection of this gear tooth geometry reduces the total tooth Hertzian and Weber

bending deflection to 0. 0009 at the high point of single tooth contact for the maximum load con-

dition to produce the 185, 000 psi Hertz stress.

The face width of the gears was modified to accommodate the axial travel for the loading mech-

anism of the Ryder rig and thereby providing full engagement of the narrow gear throughout

the operating range up to the design test objective of 185, 000 psi Hertz contact stress.

The load schedule and related data for the Phase II and III gears is shown in Table XV and

Table XVI. Complete assessment of the 6. 0 diametral pitch gears is made by DDA spur gear

computer program and is shown in Appendix I.

Table XV.

Phase II and III test schedule -surface stress.

Surface stress at

Test time Total cycles Torque NorlAal tooth pitch line (psi)

(hr) (X 106) (lb-in.) load (lb) Titanium" Steel**

2 1.68 176.3 111.1 60,000 79,430

2 3.36 239.9 151.3 70, 000 92,650

2 5.04 313.4 197.6 80,000 105,910

2 6.72 396.6 250.1 90,000 119,150

2 8.40 489.7 308.7 100,000 132,380

10 16.80 592.5 373.6 110,000 145,640

10 25.20 705. 1 444.6 120, OCO 158,750

10 33.60 827.5 521.8 130, 0(;0 172,000

10 42.00 959.7 605.1 140, 000 185,000

"*16.5 X `16

**30. 0 X 106

40

Table XVI.

Phase U and III test schedule bending stress.

Test time Bending stress HPSTC Bending deflection HPSTC

(hr) (psi) total pinion (in.)

2 3,279 0.0002

2 4, 462 0. 00032 5,828 0.0004

2 7,377 0. 0006

2 9, 107 0. 000710 11,019 0,000810 13,114 0.001010 1,391 0.0012

10 17,849 0.0014

41 (page 42 blank)

SECTION IV

GEAR %1ANU'CICTURE

The manufacture of hard coated titanium gears consists of 35 manufacturing operations re-

quirmg 24.0 hr set-up time and 30. 3 hr manufacturing time for Model Shop fabricativn. Manu-

facturin•g details sre described in the routing sheets shown in Appendix 11. Figure 31 shows

dre gear too!h profile as manufactured.

Process sequence for Phase !, I1, and IIl gears is as follows:

0 10ob

* Preplate grind (Phase I and II only)

* Plate (FeNi for Phase 1, Fe for Phases II and I11)

* Diffusion bond

* Preheat treat g- nd

* Carbonitride

* Finish grind

* Lube coat

The involute profiles were full form ground using cams manufactured by a numerical control

(NIC) system developed at DDA. This grind process ensured plating uniformity ol the entire

root fillet and involute profile.

Process dimensions are shown iD. Tables XVII and XVIII.

STooth

0.017 min0.001 min

0.002-0.0030.012-0.013

Plate

Preplate grindFigure 31. Manufacture of gear tooth profile. Preheat

treat grind

Finish grind

43 7326-31

:L _______

Table XVII.

Phase I, H, and III narrow gear process dimensions (in.).

Arc tooth Root fillet FacePhase Dimension over pins thickness Root dia Outside dia radius width

0. 3631 3. 750L0. 002 --- 3. 250±0. 005 3. 656±0. 005 ---

0.373

Hob II 3. 875±0. 002 --- 3.110+0. 000 +0.000 0.2603.803 0.-60

-0. 005 -0. 005 0.270

+0. 000 0. 266III 3.875±0.002 --- 3. 100±0. 005 3.803 " ---

-0.001 0.268

SPreplate +0. 004 0. 130 0. 363PrI 3.704 -0 3.234±0. 005 3.656±0.003 0. 048grind -0. 000 0.132 0.373

S+0.006 0.238 3.0700+0. 000 +0.000 0.075 0. 260

-0. 000 0.241 -0. 005 -0. 005 0.085 0.270

+90 000 0.240 +0. 000 +0.000 0. 079 0.266III 3.852 " 3. 075 3.808+0

-0. 003 0.242 -0. 001 -0. 001 0.085 0.268

1 0. 025 minimum

Plate II 0. 020 minimum

Tfl G. 017 minimum

Preheat 774+0. 005 0. 165 694+0. 000 0.405S 3.77 - 3.273±0. 005 3.69 0. 032treat -0.000 0.167 -0.005 0.415

grind920+0. 006 0. 278 +0.000 +0. 000 0. 058 0. 300

_-0. 000 0. 281 -0. 005 -0. 005 0.068 0.310

111 3.915+0. 000 0. 277 3.106+0. 000 +0. 000 0. 064 0. 294III .91 - 31063.839 -"

-0. 008 0.275 -0. 001 -0. 001 0.070 0.300

Fia 0 0 .17+0. 000 0 0Final 1 3.759 +0.004 0.157 3,263±0.005 3.694 " 0.034 0.400grind _-0.000 0.158 -0.005 0.410

0+0.006 0.268 3 +0. 000 +0. 000 0.062 0. 290I! 3902+0 -0 6 3. 100 3. 833 " -

.-0.000 0.271 -0. 005 -0. 005 0.072 0.300

III 3.904+0. 000 0. 268 4-0. 000 +0 000 0. 067 0. 290-I .0. 00 • 3. 100~o 00 3.833~~ 00"-0.003 0.269 -0.001 -0.001 0.073 0.294

44

"F Table XVIH.

Phase I, 11, and M wide gear pracess dimnensi-ons (in.).

Arc tooth . Root fillet FacePhase Dimension over pins thickness Root dia Outside dia radius width

3.680±0.005 -'- 3 250±0. 005 3.656±0.005 0.379

• 0.389

+00000 0.356

Ho I 3.875±0.002 -- 3.10I0±0.005 3.803 --

-0.005 0.366

+0. 000 0.210 +0000 +0.000 0.097 0.370

1In 3.79088 -- 3.075 3.808 1- .. . .-0.003 0.212 -0.001 -0.001 0. 0.372

I . 0. 025 minimum

*i

Plate * I0. 020 minimum

III 0. 017 minimum

Preheat +0. 004 0. 146 +0.000 0.521I 3.76581 3.273±0.005 3.694 0.032treat -0. 000 0.148 -0.005 0.531

grind+0. 006 0.248 +0. 000 +0. 000 0.075 0. 396

ii 3.863 - 3.110 3.843-0. 000 0.251 -0. OG5 -0.005 0.085 0.406

I 1I 3.8 0000 3.0254 3. 833+0. 000 0. 082 O. 400

S-0.003 0.249 -0. 001 -0. 001 0.1088 0.406

Final.02 mniu

Final2+0.004 0.140 0.000 0.516grind -0. 000 0.138 3.-0t0 0 .60 0005 0, 0. 0526

11 3.8+0. 006 0.'146 3.0 8 +0. 000 3.694+0. 000 0.086 0. 386

-0.000 0.241 -0.1005 -0. 005 0.090 0.396

+6. 000 0.238 +0. 000 +0 000 0. 084 0.396IIi 3.847 3.100 , 3.833 --0. 003 0.239 -0. 001 -0. 001 0.090 0.400

45

Typical inspection charts of manufacturing control are shown in Figure 32.

Manufacture of iron coated titanium gears revealed a strong tendency for the coating system to

crack during processing. A number 13 BT glass bead peen at 40 psig was implemented to pro-

v.ide compressive stresses superimposed over any residual tensile processing stresses. This

procedure also tends to unify stress distribution across the gear surface. In addition to elimi-

nating surface cracking the peen operation improved the surface finish to 16 rms. Further

improvement in the surface finish was accomplished by the Hone operation which reduced the

finish to approximately 4 rms.

Electron probe and micrographic analysis of gears with defective plate revealed residual sili-

cone carbide particles at the iron and titanium interface. These particles were suspected to

have come from the blasting or cleaning operation prior to plating. Several tests were made

and aluminum oxide was selected as a replacement media. Subsequent examination revealedvery little aluminum oxide adhered to the gears and what was present appeared to disperse

ODB- -r

S[-0.0002 in

SI"Pitch'-.....-

LPSTCtca1

7-,

•, A,

"" ..0.~~0002 i n ' " .

Typical profile chart- Typical tooth spacing chartnarrow and wide gears

OD - outer diameterODB - outer diameter breakHPSTC - high point single tooth contactLPSTC - low point single tooth contactAPD - active profile diameter 7326-32

Figure 32. Typical gear inspection charts.

46

during thec vacuurm dififusion treattinen-. The silicon carbide was no longer in evidence a-nd the

- percc-ntage of defective tivtanitum to iron difffusion bonded gears dropped to near zero.

Postheat treatment cr-acking was primarily Laused by grind induced stresses which were cor-

rected b -modification to low stress grinding procedures consisting of reduced grinding w-heel- speeds, softer grade grinding wheels, a-nd reduced infeed rates. This process was followed

by glass bead peening of t'he parm.

Finished gears are shown in Figures 33 and 34.

-~ 1

P. -1f4q

Figure 33. Phase II finished gear set.7364

47 (Miagc 48 Mi~rk)

TESTL'XGIA-IALVSiS

T'-t. T rio..e:er, designtd an.d con:.ruczed b DDA, permits the determination of static co-

e'-"IL~t- w: o. f-rIction as weli as E'.' c. .!ile of the vrea-r surfaces- This rig consists of a loading.

S:- s:t. , S-Z:orL.•. s.pei.m..en L.I.o*:r, os:-UL-.ing test shaft, and recording instrumentation.

.r .. 35 is a front vi-ie' of :he -es: rig wit;, its test parameters.

-Fr,'Lo=eter rozt ing and fiu=:ed -est secimens w..-ere fabricated from Ti 6A-2S-i-4Zr-6.Mo,

p!z-td ".,:d inis.ed as shown in I.!gure 3; and Figure 37 to maintain 0. 015 inch plate thickness

I. c 55-53 surface ha".rdness.

"Temperature-ambient

"Applied load (static)-100 lb

Angular motion-60 degrees

Oscillation frequency-16 liz

Test time-1000 cycles

t2 3 6 --

Figure 35. Tribometer test rig and test parameters.

N4

ARom - 33 M516 Beor0e .htng-f 0ish

0.515 , Indb 0±0.OO1 /lslbt

AbskMafkD and bothAfter coating-finish end faces during 0. 750 in.grind to L ODD U0.001 coating ±0.010 in.

7326-36

Figure 36. Trlbometer rcbati specimen.

300

±301

0.750 ]16±0.010 1 r 164"

±,O, 0. 600 in.

-. L0 Finish grind requirement +0.6010Si 0.500 on all surfaces except this±0.010 and opposite

Coat this surfaceprotect all others -4 11] 7T26-37

Figure 37. Tribometer stationary platen specimen.

50

•% , L . . .. . ...... ..

The fouOWAig test SecieM Stu were tested to denwmine the 09= mtenal and lIIcaat_

Ptlitinz Nome AC-INbTe, Te-IUS, vAEr,%S6 3

Irom-Ticke~l 6 6-6

Electroless nickel 6 6 6 6

TyýpiC2l I rihnometr test specimen set is shown in Figure 38.

Electroless N-ickel (N-%idimem) Hard Coating

The Ti 6Al-2Sn-4Zr-;Io, Tribometer cvir~lners aird pzat1en3 were plaed with 18 to 24 mils of

electroless nickel (Nichem), thernWIav diffuWea a1 lOOOOF in vacuum, and finish ground to 15

inils of hard coating with a hardness off Rc 55 to 58.

Because of the extrusion and piling up around the wear scars of the Tribemet-er teAts of the

electroless nickel (Nichem) hard coatings, the electrophtretic Teflon-NMOS 2 surface lubricant

coating was dropped fr( n further consideration for this programi. Accordingly, Tribometer

tests were performed with carbonitrided iron and iron-nickel alloys on the Ti 6A%1-2Sn--4Zr-

6110~ in the finish ground condition and with the spray-coated AFML (DC 1-3943) and the electro-

phoretic: Ag-N-bTe 2 solid lubricant coatings.

Carbonitrided Iran and Iron-Nick-el Hard Coating

The program originally included the use of diffused electraless nickel (Nichem) as the bonding

medium for the iron and the iron-nickel alloy hard coatings. Unfortunately, by the timie it wras

7326-38

Figure 38. Typical Tribometer test cylinder and platen.

51

iii-M, "I'-

01=e hh =ca Sarke LWBze4. thefoe VMS ded to beat treat tib'e- spetipens toTale L if Sui =M"t 2tq=e boa we :.ec scr a m Ib for the TrKWoftt tests.

Pw~~ i.u tcc tbws ae ob rue; hXr~, 2S te teuSM~ bereM it w~uas e~d~ umha the

bedng syste voald rze s.rtive the Trzbeter tests. Figure 3-2 illmstrafes the faiinres

~eiece:the veak bo aild E21- ME applied 102ad t2- I_~ E"COatiuns fatigued and Ir2C-tc"!d ~ strp -i -y Laie in the pw Ygram it w-as then aecessary to produce iron a--d iron-

rCiekel 2110T Tr70 erW SPeCi-meMS WEi X hed been beaded bv thee thermal difso procedu~re..

Figure 40 and Figare 41 show the eatrc-e li-is of uwear scarr profiles; with their test speci-

Tanle XMX is a summaryt of the u-ear scar deptrhs and a summary of friction tests is shown inFigure 42.

Tribometer Test Conclusions

* Tribmeter testing reveals little difference between vacuum diffasec, double tempered,

carbonitrided iron and iron-nickel as hard coating materials.

o The electrophoretic Teflon-iMoS2 surface lubricant shows good properties. Howe-er, this

lubricant's appreciable alteration of surface geometry by extrusion displacement make it

a questionable choice for highly loaded lubricated surfaces.

* AFML-41, surface lubricant prov-ides optinum protection for all of the materials tested.

* Carbonitrided iron + AFML-41 produced the least surface disruption.

7326-39

Figure 39. Typical failure Fe and Fe-Ni coating with

electroless Ni bond medium.

52

~7No.

____ -bdt W-41---o.

_______ ~No. 1

.- o

3 2X

~ Figure 40. Results of Tribometer testing of bare finish ground electrol s- Ni.

-72 No 2 .

- No. 2

-~ew - no.- ~. 4;

Magn: 2X

Figure 41. Results of Triborneter testing, of carbonitrided Fe + AFML (DCI-3943).

Table M(LX.

somrna.-Y of tribameter wear Scars.

Cwcdiica Wear scar dceph (in.)

Ejectroless nickel (bare) 0.000290

Elect-oless nickel -AFMIL-41 0.000063

F-Jecroleb- -nickel - Ag-N-bTe-v 0.000110

Electroless -nickel t-Trflon-1MoS7 0.000028

Carbonit-ridei iroei fbare) 0-.000048

Carbonitrided ironI Ag-N\bTe,, 0.000026

Carbon-itrided L-on AFAML-41 0.000013

Carbonifridc-d iron-nickel (baz-e) 0.000026

Carbowntrided iron-nickel Ag-MoTeg 0. 000077

Carbor-itridedi iron-nickel AFNIL-41 0. 0000 Is

Static coefficient of friction

- %0 Zý 0% hi _J 00

Electroless nickel (bare)

Electroless nickei + AFML -41

Electroless nickel + Ag-Ntire

Electroless nickel + Teflon-MoS2

Carbonitrided iron (bare) ý U ý UHCarbonitrided iron + Ag-NbTe2

Carbonitrided iron + AFML -41Carbonitrided iron-nickel (bare'?nhiuuinlsinCarbonitrided iron-nickel + Ag-NbTe2 niinlniCarbonitrided iron-nickel + AFML-41

Be-,i n n jg of testAfter 1000 cycles lllll

7326-42

Figure 42. Summary of Tribometer friction testing.

5.5

THREE-BALL-A ND-CONE TESTS

The DDA-designated three-ball-and-cone test facility consists of eight units for the evaluation

of materials under high Hertzian rolling contact fatigue loads. Figure 43 is a view of the

typical test rigs in DDA Materials Laboratories and Figure 14 shows a schematic of the rig

system. The test facility consists essentially of a high speed shaft which holds and drives the

test cone specimen; a bottom fixture which retains the three ball bearings and outer race; a

temperature controllable positive pressure lubricating system; loading piston; and automatic

shut-off controls. The test performed with this facility is comparable to the cyclic compres-

sive or crushing load in gear and bearing usage. Both lubricated and oil-starved testing can

be performed up to 600, 000 psi HIertzian stress levels.

Test Parameters

* Test machine speed, rpm 10, 770

* Stress cycles/hr 1,518,570

0 Test cone surface fiaish, rms 4

* Total system vibration at origin of test, rms volts max 0. 3; optimum 0. 1

* Contact ball permanent set None

* Lubricant temperature, OF 190 to 200

* Lubricant MIL-L-7808

RaceTCC O0i1 return

Test oil Oil supply

Loading piston

7326-43 7326-44Figu..e 43. Three-ball-and-cone test rigs. Figure 44. Three-ball-and-cone fatigue

tester schematic.

56

-- ____ __ ______

Cone Test Specimens, Figure 45 were manufactured with 15 mils of iron-nickel or electroless

nickel plating over Ti 6AI-2Sn-4Zr-6Mo. The specimens were tested bare and with Ag-Nb-

TeO2 and MoS2 -SbO 3 lubricant coatings as follows.

Surface lubricant coating

Plating None Ag-NbTe 2 MoS2 -Sb 2O 3

Iron-nickel

Single temper 8 - -

Double temper 18 8 10

Electroless nickel 14 8 8

Figure 46 shows a finished test specimen together with the bearing balls and outer race used

on the three-ball-and-cone tests.

The following cone fatigue tests shown in Tables XX, XXI, and XXII were run to determine the

endurance limit of the various combination of materials and surface coatings.

Figure 47 is a summary of the cone fatigue tests which show their respective fatigue life values

relative to AMS-6265 carburized steel.

A typical pitting fatigue failure is shown in Figures 48 and 49.

324 (Pol ish)

109.60°0

109.28

O. 500 dia.0. 4%

±0.301. 000 "

Break edges 0. 015 - 0. 030 RScale - 4 x size 7326-45

Figure 45. Th'-ee-ball-and-cone rig test specimens.

57

7326-46

Fgure 46. ThreeoIm1-and-cone test specimens.

:I .I_,-AMS 6,-aruized steel

amE

L)

10N jo g 8 io'• 1010Celes-Hz

7326-41

S~Figure 47. Three-ball-and-cone test summary.

S77326-48

Figure 48. Typical cone specimen failure.

58

Table XX.

Three-ball-and-cone test results--iron-nickel alloy.

Specimen Load level Stress

SNo. Hertizian (psi) cycles Dispositon

Carbonitrided iron-nickel alloy vacuum diffused, single temper-lubricant: none

4 600,000 3.9 X 105 Failed

6 600,000 3.1 X 105 Failed

2 500,000 6.8 X 106 Failed

5 500,000 4.2 X 106 Failed

7 400,000 1.5 X 107 Failed8 400,000 6.9 X 107 *1 300,000 4.0 X 108 Failed

3 300,000 1.0 X 108 **

Carbonitrided iron-nickel alloy vacuum diffused, double temper--lubricant: none

S11 600,000 2.5 X 108 Terminated

13 600,000 1. 1 X 108 Terminated14 600,000 3. 1 X 108 Terminated

17 600,000 8. 7 X 107 Terminated

20 600,000 2.5 X 105 **

21 600,000 2. 6 X 108 Terminated

22 600,000 1.6 X 107 Failed

12 500,000 5. 8 X 108 Terminated

23 500,000 6.9 X 108 Terminated

24 500,000 9.2 X 107 Failed

25 500,000 --- **

26 .500,000 6.8 X 108 Terminated

9 400,000 1.1 X 109 Terminated

10 400,000 1. 1 X 109 Terminated

Carbonitrided iron-nickel alloy vacuum diffused, double temper, peen-lubricant: none15* 600,000 7.7 X 105 Failed

16* 600,000 1.4 X 106 Failed18* 600,000 5. 7 X 106 Failed

r 19* 600,000 1.4 X 107 Failed

*Abnormally high vibration--surface finish: rms 15 to 17.

**Abnormal failures are those which show eccentric wear patterns, fail at test inception,

or experience high initial vibration.

59

Table XX1f.

Three-ball-and-cone teq results-iron-nickel alloy and iron.

Specim'en i Loaq level Stress

No. Hertizian (psi) cycles Dispositon

"Iron-nickel alloy vacuum diffused, double temper-,lubricant: MoS2 -SbO3

3 600,d00 1. 1 x 108 Terminated

4 600,000 i - *

10 600 000 2.3 X107 *

.5 500,C00 2.5 X 10 7 *

6 500,00) 1 7.9 X 108 Terminated

7: 500,000 4.7 X 10 8 Terminated

8 500,000 7.7 )ý 107 Failed

9 500,000 --- .

1 400,000 2.5 X 107 Failed

2 400,000 4.4 X 10 8 Failed

Iron-nickel alloy vacuum diffused, double temper-7lubricant: Ag-Nb-te 2

1 600,000 A.-

2 600,000 ---

3 600,000 --- *

4 60,0 000 1 1.8 x 108 Te. .ninated5" 500,000 2. 1 X 108 Terminated

6 500,000 5.7 X 108 Terminated

7 500,000 6.8 X 10 7 Terminategd

8 500,000 6.8 X10 7 Terminated

*Abnormal failures are those'which show ecdentric wear patterns, fail at test

inception" or experience high initlal vibration.

Oil Starvation Testing

Oil starvation testing attempts to shut-off the lubridant and create an oil starvation failurewere unsuccessful. tResidua.l lubrication was sufficient to allow' test termination (over 1.0 X

* 108 stress cycles) on bare specimens without failure.

Three-Ball-And-Cone Test Conclusions

The followinb Lonclusions have been made concerning the compressive load capabilities of the

systemis based upon three-ball-and-cope testing. Also refei to Tables XX through XXII,

0 The Nichem system has extenpive scatter of results not attributable to test variations and

is inferior to carbonitrided iron-nickel. Further pursuit of the Nichem syptem is not

recotnmended ac this time.

60'__ _ _

Table XXIL

Three-ball-and-cone test results-electroless nickel.

Specimen Load level StressSNo. Hertizian (psi) cyvcles Dispositon

Electroless nickel (Nichem) hardened and aged-lubricant: nonei

1 600,000 1.3 X 104 Failed

2 600,000 1.3 X 104 Failed

11 500,000 7.2 X 105 Failed

12 500,000 6.1 X 108 Failed

14 500,000 3.7 X 105 Failed

5 400,000 4.9 X 105 Failed

6 400,000 2.5 X 108 Failed

9 400,000 5.0 X 107 Failed

10 400,000 9.2 X 107 Failed

3 300,000 1.4 X 106 Failed

4 300,000 1.4X 106 *

7 300,000 4.8 X 104 *

8 300,000 6.1 X 107 Failed13 300,000 7.6 X 108 Terminated

Electroless nickel (Nichem) hardened and aged-lubricant: MoS2 -SbO 3

Si 3 400,000 1.5 X10 6 Failed

S4 400,000 1.1 X 106 Failed

1 300,000 9.0 X 106 Failed

2 300,000 1.2 X 107 Failed

5 300,000 2.1 X 106 Failed

6 300,000 8.7X 108 Failed

7 300,000 4.1 X 108 Failed

8 300,000 4.0 X 106 Failed

Electroless nickel (Nichem) hardened and aged-lubricant: Ag-Nb-Te 2

1 300,000 3.1 X 107 Failed

2 300,000 1.3 X 106 Failedi3 300,000 1.5 X 108 Failed

4 300,000 3.5 X 106 Failed5 300,000 2.8 X 106 Failed6 300,000 3.2 X 106 Failed7 300,000 3.6 X 106 Failed

8 300,000 --- *

*Abnormal failures are those which show eccentric wear patterns, fail at test inception, or

experience high initial vibration. 61

S~7326-49

Figure 49. Typical microsection of pitting fatigue failure.

0 The iron-nickel alloy system appears competitive with cased steel test results.

0 T£est termination to accomplish the greatest quantity of evaluations precludes determina-

tion of the maximum fatigue capabilities for the material. However, the data to depict

minimum values.

0 Double temper of the specimens is a definite improvement and is considered a direct asset

to both bearing and gear life.

0 Lubri•cation coatings do not appear to have any positive influence on three -ball-and- cone

{ test specimens.

!R. R. MOORE TESTS

} Three groups of Re R. Moore test specimens were fabricated of Ti 6A1-2Sn-4Zr-6Mo. One

i group was tested bare after being processed through the thermal treatment that the gears

} would receive. The second group was iron plated and the third group was iron-nickel plated.

S~Both plated groups were processed as shown in Table XXIII.

S~The Re R. Moore specimens as shown in Figure 50 t,,ere tested to establish their fatigue en-

I durance limits. Test results are shown in Table XXIV.

: Both iron and iron-nickel coated titanium show lower fatigue life than bare titanium, with

relative summary shown in Figure 51.

Electron Microscope Analysis

Representative fractures of each group are shown in Figure 52.

62

I

Table XXIIL

Thermal processing of R. R. Moore plated

fatigue test specimens.

Temperature (*F) Time (hr)

Diffusion 1600 3

Slow cool

Carbonitride 1600 6

Quench Oil

Temper 350 1

-100 1

350 1

500 12

7326-50

Figure 50. R. R. Moore test specimen.

00 B tita nium90 - .

80

Ce7-j I 5 Iron-plated titanium

603

.Iron-nckel-plated titanium

0105 106 107 108

Cycles-Hz 7326-51 7326-51

Figure 51. RI =R. Moore fatigue test summary.

63

Table XXIV.

Results of R.R. Moore fatigue tests.

Condition Stress (-ksi) Cycles X 10 6 Results

Bare Ti 100 0.046 Failed

100 0.043 Failed

90 6.587 Failed

75 33.827 Tervinated

75 18. 519 Terminated

50 14.677 Terminated50 13. 135 Terminated

90 0. 125 Failed

90 9.022 Failed

Fe plated 100 Failed on load

50 4.646 Failed on load

50 0. 075 Failed on load

50 0. 030 Failed on load

45 4. 3E4 Failed on load

45 ,. 960 Failed on load

40 59.037 Failed on load

FeNi plated 60 0.057 Failed

55 1.061 Faileu50 7. 84t6 Failed

50 2. 945 Failed

50 2.848 Failed

40 63. 578 Terminated

40 37.2.76 Terminated

7326-52

Iron Iron-Nickel Bare Titanium

Figure 52. R. R. Moore test specimens.

64

Fractographic studies were made of both the iron and iron-nickel plated titanium specimens

show the following results.

0 No striations typical of fatigue were present in either the Fe or Fe-Ni coating areas.

Fatigue appears to initiate in the titanium at the interface below the coating.

0 * While the iron or iron-nickel coating appears to have failed in a simple overload at the

beginning of the test, the subsurface titanium then progressed for a period in fatigue

originating at or just below the diffusion zone.

R. R. Moore Test Conclusions

0 Both iron and iron-nickel have lower fatigue capabilities than bare titanium.

0 Fractographic studies indicate that fatigue appears to initiate in the titanium at the inter-

Lfce below the coating.

CRUSHING TESTS

Crushing tests were performed to determine the effect of 2 mils of up-hardened iron at the iron-

titaiium interface.

A block of Ti 6A1-2Sn-4Zr-6Mo was constructed and iron plated to a finish ground depth of

approxima.ely 0. 015 inch.. This surface was given a 2 hr carbonitride.

Subsequent load tests revealed the following:

Load, ksi Deformation

300 Yes275 Yes

250 Yes

225 Yes

200 Marginal

155 None

Subsequent examination revealed no indication of subsurface cracking in the areas of plasticdeformation.

Crushing Test Conclusions

* Static Hertz crushing stress up to 200 ksi will not produce visual deformation of an iron

plated surface of Rc 55 nrin hardness.

* Static Hertz crushing stress above 200 ksi produces permanent set of an iron plated sur-

face of Rc 55 min hardness but will not cause subsurface cracking.

65

RYDER GEAR

Small-scale titanium gears submitted for Ryder Gear Machine testing during this program

"were grouped into three phases:

Phase I Gear material: Ti 6A1-2Sn-4Zr-6Mo

36 teeth, 10. 29 pitch

Hard coated with iron-nickel alloy

Lubricant coated with AFML-41 (MoS2-SbO 3 )

Phase R Gear material: Ti 6AI-2Sn-4Zr-6Mo

21 teeth, 6.0 pitch

Hard coated with iron

Lubricant coated with AFML-41

Phase III Gear material: Ti 6A1-2Sn-4Zr-6Mo

21 teeth, 6.0 pitch

Hard coated with iron

Two sets lubricant coated with AFML-41

One set black oxide surface treated

Typical Phase I and Phase 1/III gear sets, before lubricant coating, are shown in Figures 53

and 54.

7326-53

Figure 53. Phase I type gear: 36 teeth, hard coated with Fe-Ni alloy.

66

ii

I

T326-54

Figure 54. Phase 11/MI type gear: 21 teeth, hard coated with Fe.

Dynamic testing of the small-scale gears was conducted on a Ryder Gear Tester modified by

DDA and consisted of the following major components:

* Ryder-ERDCO Universal Drive Stand and Control Console

* ERDCO Antifriction Ryder Gear Head, Model R-5589

0 ERDCO-CRC Test Oil Cart, Model 2300S-2

* Moore "Nullmatic" Load Control System

The modified Ryder Gear Tester is capzble of performance testing a wide variety of gear ma-

terials and designs, heat-treatment techniques, bonded coating materials, and coated and

liquid lubricants.

Conditions simulating ful]-scale gear tooth crushing loads and tooth bending stresses can be

readily applied and accurately maintained at temperatures up to 300°F. Equipment features

are shown in Figure 55.

67

7326-55

Figure 55,, Ryder-ERDCO gear tester with antifriction gear head and CRC oil cart.

Test Parameters

The following test parameters were maintained throughout the test program as specified:

0 Test gear speed, rpm 14, 000 ±50

e Test oil specification MIL-L-7808G

• Test oil flow rate, ml/min 1, 300 ±25

* Test oil in temperature, OF 135 ±5

0 Test oil system capacity, gal 2

• Test oil filter, microns 10

0 Test gear load, psig As shown ±0. 25

"4Increased to 1, 600 ±25 during last three tests of Phase III gears.

Test Gear Load Schedules

The small-scale gear teeth scuffing and pitting fatigue limits were determined under conditicns

simulating full-scale gear teeth crushing loads and bending stresses. The Phase I gears were

36 teeth, and the Phase II/III gears were 21 teeth gears. The differences between the two gear

designs necessitated two separate load schedules, and these are compared in Table XXV.

68

Table XXV.

Load schedules for small-scale titanium gears tested in Phases I and 11/11L

Normal tooth load Surface stress at pitch

Test time (hr) Torque (IbIin.) (M) line (psi Hz)**

Phase I 11/111 I 11/I I 11,/1 1 11/111

10.0 2.0 470.3 176.2 296.5 111.1 105,930 79,430

10.0 2.0 530.9 239.9 334.7 151.2 112,550 92,650

10.0 2.0 595.2 313.3 375.3 197.5 119,170 105,910

20.0 2.0 663.2 396.6 418.1 250.0 125,790 119,150

20.0 2. 0 734. 9 489.9 463.3 308.7 132, 410 132, 380

20.0 10.0 810.2 592.4 510.8 373.5 139,030 145,640

20.0 10.0 889. 2 705.1 560. 6 444. 5 145, 650 158, 870

20.0 10.0 971.9 827.5 612.8 521.7 152,270 172,000

20. 0 10. 0 1, 058. 2 959.7 667.2 605. 1 158, 890 185, 370

*Phase I is a 36-tooth load schedule.

Phase Ul/III is a 21-tooth load schedule.**Based upon Young's Modulus: 30. 0 X 106

Test Gear Inspection

The narrow test gear teeth were inspected under magnification upon the completion of each

timeiload increment, and after each equipment shut-down, whether scheduled or unscheduled.

Gear teeth were evaluated on the bases of relative rate of tooth face scuffing, pitting fatigue,

compression cracking of the hard coating, loss of hard coating, or other isually observable

distress. Wide test gear teeth were inspected without magnification at thc same time. De-

tailed metallurgical investigations were conducted on the gears only after test termination.

Ryder Gear Test Data

A tabular summary of each gear set installed and tested on the Ryder Gear Tester during this

program, the maximam test time, and the condition of the gears at test termination is pre-

sented in Table XXVI. Detailed data recorded at each inspection of the gears will be found in

Appendix III.

Metallurgy Analysis

Phase I Analysis

Test I. 1-Tooth fracture of wide gear shown in Figure 56 progressed from surface blemish.

Narrow gear showed only minor tooth scuffing.

69

Table XXVL

Summary of Ryder gear tests conducted on small-scale gears

during Phases I, H, and Ill.

Phase I

Test Gear Gear Total time Maximum

No. set No. width (hr) stress (psi) Gear condition at test termination

I i-A Narrow 30.0 119, 170 No failure, normal scuff wear only

1-B Wide Tooth 35 broken: all others normal scuff wear

2 2-A Narrow 14.0 105, !30 Overtemperature due to lubricatior, loss

2-A Wide Overtemperature due to lubrication loss

3 1-B Narrow 10.0 105,930 Teeth 13-18 broken: others show impact damage

2-B Wide Lmpact damage on numerous teeth

4 3-A Narrow 2.5 86, 100 Mtisalignment: excessive wear on all teeth

3-A Wide Misalignment; excessive wear on all teeth

5 4-A Narrow 17.4 112,550 Tooth 34 broken; plate loss on other tips

4-A Wide Plate loss on tips of numerous teeth

Phase 11

I 2-A Narrow 6.0 105, 910 Misalignment; no observable damage

2-A Wide Misalignment; no observable damage

2 2-B Narrow 12.5 158,870 Plate damage on teeth 6, 7, 12, 15, & 19

2-B Wide Minor scuffing, no observable damage

3 3-A Narrow 12.3 158, 870 Plate loss on all teeth*2-A Wide Plate cracked on all teeth

Phase III

I I-A Narrow 1.0 79, 430 Loose nut permitted misalignment; compression damage

1-A Wide Misalignment:. some compression damage

2 I-B Narrow 0.1 79,4-.0 Loose nut permitted misalignment: compression oamage

1-B Wide Misahigr;'cnt.. plate loss on teeth 10-13

3 2-A Narrow 29.2 158, 870 Tooth 7 plate loss;: plate smeared on other teeth

2-A Wide Plate smeared on numerous teeth

4 3-A Narrow 19.5 145, 640 Gear web fractured:, minor scuffing on all teeth

3-A Wide Minor scuffing on all teeth

5 2-13 Narrow 21.7 158, 870 Tooth 7 broken; scuff damage on all teeth

2-B Wide Minor scuff damage on all teeth

6 4-A Narrow 8.0 119, 150 Tooth 18 plate loss; minor scuffing on all teeth

4-A Wide Minor scuffing on all teeth

Note:, Phase I-Gear sets 1, 2, and 3 coated with iron-nmckel alloy,

Gear set 4 coated with iron only.,

Phases II/I1--All sets ,oated with iron only.

'ýPreviously used in Test 1 for 6. 0 hours under load,

70

L

Test I. 2-Test rig failure causing loss of lubrication caused premature gear failure. No gear•. analysis made.

Test I. 3-Fracture of narrow gear teeth resulted from multiple indications of fatigue failurein the area of high nickel concentration in the tooth root fillet area. Figure 57 shows the frac-tured tooth failures.

-7326-5,6

Figure 56. Wide gear tooth fracture.

7326-57

Figure 57. Fractured gear teeth induced by fatigue failure.

71

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prne 59.. Phase IL.2 gear ktoth damage.

Fracturing of the iron was predominantly along a plane at the irohi to titanium interface see

Figure 61. Microexamination revealed localized areas of diffusion zone cracking in a plane

relatively parallel to the interface., In addition, 'light cracking of the iron plate was observed

normal to the gear face.

Test 3-Heavy spelling and loss of case was noted on nearly every tooth of both gears as shown

in Figure 62. Daxmiage is attributed to poor bond of the iron coating.

Phase III Analysis

Test 1 and 2-The gears were installed with low retaining nut torque which resulted in fatiguefailure of the lock washer tab. This allowed the lock nut to back off resulti-g in misalignment

and damage to the gear teeth. The gears were turned over and the same hsembly conditionduplicated. A sifrAlar failure resulted as shown in Figure 63. Gear tooth dimage is shown in

Figure 64.

Test 3-Damage to the gears is shown in Figure 65. Photomicrograph typifying the narrow

gear case structure is shown in Figure 66. Microexamivation subsequent to test showed a

plating line defect which led into the diffusion zone and provided a weak junction at Vhich failure

occurr'd.

.I

T26-e1

Fr=e 61- CEc~z 60=5imair r4e -jacd~r

Mgfl: ix7326-62

Figure 62. Phase H1.3 gear teeth damage.

A2- l *uC ,=tbkc

724 A

Figure 64. Phase 1l1. 1 and .2 ;ýear damage by loose retaining nut.

pj

M-3 !ttI

Test 4-Metallurgical examination revealed a fatigue gear we. failure originating in a process-

ing defect and progressing from tht gear tooth root fillet toward the hub, see Figure '37.

7326-66

Figure 66. Phase EEI plating line defect.

M6-67

llre 67. Gear web fait=re.

Test 5-Photomicrograph Figure 68 shows satisfactory case condition in areas adjacent to the

tooth fracture.

Tooth failure of the narrow gear is shown in Figure 69. Fractographic analysis indicated noevidence of fatigue. The extremely rapid fracture is indicative of an overload such as foreign

material going through mesh of the teeth.

P-26-08

Figure 68. Case condition adjacent to failure.44

2ge - t

7326-68

Fiue68-aecodto adaettofiue

>t7 * .

/'.4

Test 6-Photomicrographs shown in Figure 70 are typical of the case structure. Surface

spalling or fracturing is along the diffusion interface. Although fracturing is in the diffusion

zone, titanium base metal can be seen breaking away with the iron case. The bond integrity

in the gears is considered excellent.

Gear Test Summary

The common basis selected was i07 cycles 'o evaluate the fatigue strength of the test gears

relative to hardened steel gears. Figure 71 shows the pitting fatigue stress level of the titanium

gears relative to hardened steel gears. DDA experience design criteria for hardened steel

gears is 242, 000 psi with a negative reciprocal slope value of the S/N curve of 12. 08. The

AGIVMA standard 210. 02 allowable contact stress for 107 cycles is 180-225 ksi for Rc55-60 case

hardness for steel gears.

6The initial contract objective was to achieve 150 hr of operation or 126 X 10 stress cycles at

132, 000 psi (based on steel modulus of elasticity or 100, 000 psi based on titanium modulus of'7

elasticity). This stress related to 107 stress cycles by the slope of the stress-cycle curve is

163, 000 psi.

As the program progressed the objective was established at stated loading cycles of different

stress amplitudes starting at 105, 500 psi and progressing up to 158, 000 psi at 150 hr of test

time. The cumulative damage in fatigue based on Miner's rule is 147,300 psi at 150 hr or

181,600 psi at 10' cycles.

73O6-70

F4•re 70.. P•..-omi- typical of the cae structare.

190, 100 psi Phase II, Ill equivalent objective181,600 psi Phase I equivalent objective

1000 1 163,000 psi equivalent contract objective-f -_ - 152,000 psi Phase III equivalent accomplishment

Steelgear pitting fatigue life- 120,000 psi Phase II equivalent accomplishment

St.147, 300 psi Phase I objectiveS100 --- * - __ 132, 000 psi contract objective

- f 169, 000 psi Phase'l i,'l objective

__Phase I testscheduleSX --- \Phase I I test scheduleý

_ _ '143,000 psi Phase III accomplishment__ 120,200 psi Phase I I accomplishment

94,800 psi Phase I accomplishment96,000 psi Phase I equivalent accomplishment

1 1 1 1 I 11 1 1 1 1 1 1111006 107 108 109

Number stress cycles 7326-71

Figure 71. S/N test schedule.

Phase II and III objective was also a step loading with the stress amplitude starting at 79, 500psi and progressing up to 185, 000 psi at 50 hr of test time. The cumulative fatigue damage at50 hr is 169, 000 psi or 190, 100 psi at 107 cycles.

The average cumulative life of Phase I test results is 94, 800 psi at 12. 07 X 106 cycles or96, 000 psi at 107 cycles for Phase I.

Phase II average cumulative life is 120, 200 psi at 9. 9 X 106 cycles or 120, 000 psi at 107 cycles.

Phase HI average cumulative lif, is 143, 000 psi at 1.9. 9 x 10 cycles or 152, 000 psi at 107cycles.

The equivalent stress levels compared at 107 cycles are:

242,000 psi DDA experience

180. (*0-225. 009 psi AG!(;A allkoable

1"0. 100 psi ?ha.-e 2 dx 11d Il Ct•T!-,e

Vi.

181, 600 psi Phase I objective

163, 000 psi Contract objective

152, 000 psi Phase HI test achievement

120, 000 psi Phase II test achievement

96, 000 psi Phase I test achievement

k ~SECTION VI

CONCLUSIONS AND RECOMMENDATIONS

The coated titanium gears achieved 93% of the initial contract objective or 63% of the fatigue

strength of hardened steel gears. A review of the developed processes for hard coated titanium

gears indicates:

* The plating procedure required excessive attention in the program and will continue to

present a plating challenge due to the problem of obtaining equal plating distribution on the

irregular geometry of the gear teeth

0 The wear surfaces of carbonitrided iron were excellent and appear to be comparable with

hardened steel gears

0 The predomir.nte failure mode of the tested gears was at the interface of the iron and

titanium

o Specimen testing displayed excellent compressive strength properties for iron-coated

titanium

* Model shop fabrication costs for titanium gears was 20le greater than hardened steel gears

It is recommended that further exploration of iron-plated coatings be attempted to develop

added strength and ductility in the diffusion zone by solid solution forming elements at the in-

terface. The relative improveme.' -'-:.,ald oe explored by free-free bending tests followed by

additional Ryder gear manufacture and test.

Since iron-coated titanium three-ball-and-cone tests showed a pitting fatigue strength com -

parable to hardened steel, it is recommended that a program be initiated to adapt this process

to rolling eleaiunt bearing inner and ou,-r races and their rolling elements, titanium shaft

splines, and to the technology of making bearing races integral with titanium shafting by the

iron coating process.

83 $g 4 b1ank)

Appendix I

COMPUTER OUTPUT OF THE DDA GEAR DESIGN PROGRAM

ýXjLLIL Sf'aJF 'W HEt IC I. GEAR OATA-- -

P~iiW,~'±l' ~j'~t ~ 41S AL-) ~ - - ~--)r cC,'rLVT) 07/0)3/67 - -

- (~.4Rl1vIsF'1 c;IO/70 -

C'u'*(P4~týT OATE IS 72/054

*f P Di .T 47 S-E C'-T-Tc'1 C-- - -

OiPT. P')OJCCT Eflo w.. Or LO1NG UiP. - -

%; -- f.- -No.'. " NO. -- COPIES -SHORr-m Rm--- -- -

tilAAPLT'j, M'.R; 3 D153-2 A'(186J27- I 'CoNr _____

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TF-tVtLS CELT-A AriLE .... .0... . 0-

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[coo

4I S rL LA EqUS r' A IA S F T1LI V(N

CINTCA LA'Jt k;:Fck4 - pnINr OF T'AN,ENqCY WItq VDLLITE)I TH soC Acc.Crt'IlT ICN CENTER LINE TOOTH RlEFERFqCE -

Y V y y 14TPX0.O 44C'7 1. oaO4,ý b (*)CU91U 1.52257S73 411' Rs MA OR 3.21778?222 O1812 1605

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15 2 1 I L 3~2 7 . 13 7 C 0 -623152o2 "AX RF HAX OR 3.21862461 0.1f ICS659 .;6004?q

-- G - (0 iLLCT CO Ir ItATýS -ýA

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_______99

DEFLECTION SECTION

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P 14 7~9 6 -an ___.CC~cL Cl01; 1.560:ftC 0Wls - 25.066ooO S1 0.0o -

* 455* *0 0*59 S t080 14 ii95 4SS* S t wo' s ii 4 - .*SSaaae

Nt~ ~ 21.00 RVE'J1a 1.156-0b00 REO". 1.7S0D0066 RA'FCG- 1.51663S6 RS-0OD . -

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V~f -Z[!t. - 1.540jo200 lsR'ýs 1.5,025 - 94Pi IT.S4925

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'TTa-0fVLV Pr*IrrjI C-Nt'-y~ ToiuS, i., aa~n. ACTU-L 0INrI.M 'CCv1.tCT RA0US _____________Tl:F's P C2R.~ECTIC4WIUtA'XE 47; PflTVTTC----------------- V___________

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-;X3-t5 . .s7ZZ12'.6 .21 -ý252s. 1.9076±07a .764cC033 0.0002'7960 03.00391755 C.fed4Wb 6.W 0 r6-6-2 1-4- .5~Z~5 155.5L12.1157C6 94~ 1.6J341455 ?.324C5342 0.003j2a5! 0.00,379677 0.36o'd15ol 6.010~I -v -

I. 07,( 1 32,. '~267L 773I5IZ.B3757533Bc3017 0.356! C.'v60-TG7U~T~6 1T ~f7113 1.z7ocSA_ e. t 3Cr.6 ,*, a.65.70s.3t- 2.9102S255 6.000?1524 0.00061561 0O.,0042&9)-rO-.661Tn7182

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_~1;7525ý1Z) 1.711-i5z,7 '..5117it.E- 3..36_6C0i 2.477O'.6a 30f0057155 0.00031-826 0'. )0 043 574 0.001'32555T1a1761t5, .~A.' S.4--3701., ;.Eql;290*3 i..94463777 0.00070375 -3.01026776 O.u05anZI96 0.aol~R"3A -

i~3~c..7.1r57i T3I7 ~7.9,147a53-. 2.72227S66T ; 0t;324.V4 0OD3DO42461!.e5L5o42 1.cbS.2,5 7..175503C 2.50a~219OO; 2.;4!0!31 0.0004.3225 0.000a23229 0.00042411 0353W

1 ."72117Z!, J.M5"1252 2..AA.~ .35710726s 2.'3-34C5'5 3.00107r1a 0.0032IS;Q 0.0004178S 0.'016A6131

';3- _z .6...,-I- ,.'1376t& 2.22571014 2.7492-,2:5 03.01171"5 0.0)020640 0. -00917 0.00170151- .iOl& i4, 'j2' .793'9 ;0.12054105 ?.714560Z7 3.00135350 0.0001961a 0.03039674 13.001952"63

go0

EQUIVALT LOAD LEVELS FOR S2"1L GEARS-

S±*;,A S:A.E COATED TIT•'•'JIJ- G5AQS - TEST DATA - 'YDEU E = 30.0 C 13•P5

-6 - .30effective, face. width r- .25

TEST RYt-P. HERTZ %TS,-lVIJ ':!PXAL TANCE.ITIAL HP rP! 4 4!A•!TIh.E GAII 51F S TISS *Lit 1 !LB) (I.P.) TPA"EIL

7.n17 400O. ',.,9 28.17 25.!? 9.9?. 1,12.70 C0.00252 iVO00.%...66 45000. 6,. •6 35.66 -. 32.I32 .... I.2°56. -14-Z.b3 .. 0.0031-f! 1,4000.,4. 41) 5fl000. 6.1?. 44.402-- 3 .-.-- 5S- 170-.-C.3? i4000.5..27 55n0n. .4.4q 5:3.;.7 48.'r. -- .18.77 - 213.07 0.004•7, lADO.6.339 0W000 .30n.'. (,'. 39 57.25 22.33 253.57 C.0C56( 2/OC.7.440 65000. 11,1.0n 74.40 .67.43 26.21 297.59 0.00664ý 14000.8a62R 70000. ! ll..85 r6.28 78.2(0 30.40 345. 14 0.00770 1"ocC.o9.3 0 -5 75000. 157. i0 99.05 F90-77 34.90 39".20 0.00(04 ý 140'0,.

- 11.770 0000. 18.7-V, 112.70 102.•4 39.71.- 450.79 C.,UO, -24",00C.12.72? P5000. 1111.7- 127.23 115.?.! 4.011-2 . 50, 8.90 0.01136 1'.00014.263 90000. 226.22 142.63 !29.27 50.25 570.53 0.0127,' ,'W0C.15.392 95000. 252.06 158.92 144.03 55.99 635.69 14.0:19/!n 11000.17.600 100009. 279.20 176.0A9 159.5S - 62.0V 70°.36 C.0!ý572 211COO.19.414 105000. '07.! 1,94..14 175.95-------68.0 776.56 0.C1173- 1A0C0..21 .?307 10000. - 77.O1, 213.07 793-1- . 75.01- -_52.28 - .0L9e0 2/ -CO.23.. 1F.5qIIP,". 141.% 232.,8- . 211.06 82.05 931.52 0.02079 ".4CCO..25.'3,57 120'100. A02.17 253.57 229.CL 89.34 10 14.-.28 0.022%,' V&0O20.2"7.51 A 12,1000°. A' fl.39 275.14 249.36 96.9W.. 1100.57 0.02457 1'40c0.20.750 13"000. 1,' 09 207.59 269.71 104.35 1190.37 C.02- - le 000.32.003 135600. "no.00 320.03 290 .D.b 113.0.7 1283.70 0.ý2365 _7 900.31,. 51, d 4 0n000. ';.7.1.n 345.14 ;..1Z. tO 121.6C . 1380.55 C.030Z0 !4,,01.37"X23 1',5000. ;37.2n 370.23 335.54. 130.44IM 14980.92 0.03326. 1-'00.30.620 15(1000. 62n.1.1 396.20 359.0n 139.5e 1584.82 - 3?5 21 f '.000427. M 6 155000. 470.00) 423.06 3F3.,'2 1'. 05 1692o.23 03777 .0(0°." " 160000. 7!!/,.7 450.79 408.56 158.02 1C03.17 C.!9'C25 i'.00.47.041 165001. 7"3).36 '.79.141 434.3/,(. 16a.9f0 l%7.63 0.11.2111 -14001..50..190 17000. !(7.1V. 503.00 '161.22 179.29 2035.61 C .0 f. " V CP"O.53.n2l 175000. =15.32 539.28 £.-o.75 189'.99 2-157.11 0.&0;, 2,'.57.C -3 ll,r•O0. 0:n...,9 570.53 517.00 201.01 2232..14 0.65e.09 140 P.60.267 11; 3C0. q. .16 602.67 546.221 - 212.33 2410.6,, ,.n55n: 1/.-,,0.6.3. 1110 1s*0000. 1n00.2?, 635.69 576.1? 223.9S 2542.75 e.56T71 ! 1'CC0.66.659 195000. 1'Oi.qo 669. r 5f06 .Ift5 .235.90 267r.34. 0.05978. 0,,.70 . 45,6 2.100000. !! 37. I 7v')4.:36 •3A.37 241,1.16 2,.17. 45 C..,n28e ',oca3-

Ito

C)

:A Ll"tT'-: Tl!?.**I39P rU.,S -TEST flAT! - 5YVE- 2 lc.:;

6- .35effective face widdth - .250

TI^:' -4 q InF~ ST~cSS flnV IL3) UpL r "2 STIMSS F- .25

A..75 2.~ 5"' 2 55 f- 22.OZ 230.1)7 'A:2t'1CC

2-0 i'' ~ 11~4 10'3.12 0:.1L t'.I.57 3279.

7-0 O~~~d'f*~'*~~"~.9 1~.' 69.6! 7SA.35 Nl !,C(C 5828.

2.0 7i4.!...,.. '1Q" 1. 12 2sr.07 '2s.6' 2 ZE~.*1CO' %C223; !1Z.. 7377.

'7"ý"O ac.".V 30r 73 79.ni McX7? !234f..92 I.ft2Th5 1 9107.

100 10'~" 2.41 3 73. 5 33E;.:;( i-.0 12.:G.*.f, M436 i~ix. 019.

170 Li..C . t'.7 "Z."2 156.61 177r..29 c.36 ': 13114.

4F.770 ~ ~ ~ ~ ~ ~ ~ e 12#C.7S.$3.9 43.0 1"S

-I O 1 . -z.Anf)- 27 '2 2i76 47 .P I3..2 Zf:7029591

APPENDIX I1

RYDER GEAR TEST INSPECTION DATA SHEETS

FOR HARD COATED, SMALL-SCALE TITANIUM GEARS.

PHASE I PHASE III

Test No. 1, Gear.Set 1-A/B Test No. 1, Gear Set 1-A

Test No. 2, Gear Set 2-A Test No. 2, Gear Set I-B

Test No. 3, Gear Set 1/2-B Test No. 3, Gear Set 2-A

Test No. 4, Gear Set 3-A Test No. 4, Gear Set 3-A

Test No. 5, Gear Set 4-A Test No. 5, Gear Set 2-B

Test No. 6, Gear Set 4-A

PHASE II


Test No. 2, Gear Set 2-B


Test Data-Phase I, Test No. 1,

Accumulated Calculated surface

Time cycles stress levels (psi)(hr) (millions) Steel Titanium Condition of gear teeth

Break-in schedule

< 1 0. 14 74,816 56,502 Slight buvrish at and below pitch line

< 1 0.42 74,816 56,502 Relatively unchanged

1 0.84 74,816 56,502 Bonded lubricant confined to bottom 1/3 of most

teeth

2 1.68 81,595 61,640 Unchanged

3 2.52 88,396 66,765 Mlore pronounced wear-in pattern on most teeth

4 3.36 95,220 71,910 Relatively unchanged

5 4. 2n 102,042 77,043 Narrow gear teeth relatively unchanged; plating

bubble or blister on wide gear tooth No. 35 near

center below pitch line

Endurance test

6 5.04 108,829 82, 191 No appreciable change on narrow gear; bubble onwide gear tooth partially healed

9 7.56 108,829 82, 191 Relatively little change in either gear

12 10.08 108,829 82,191 Same

15 12. 60 115,643 87,330 Narrow teeth No. 2 and 34 initiated scuffing be-

low pitch line; approx 1/16-in. area of bubble

spalled out on wide tooth No. 35

93

Test Data--Phase I, Test No. 1, (contd)


Time cycles stress levels (psi)

(hr) .(millions) Steel Titanium Condition of gear teeth

20 16. 80 115,643 87,330 Narrow teeth No. 2 and 34 unchanged; No. 12,

13, 15, and 19 show rust-type stains near frpag

face above pitch line25 21.00 122,400 92,459 Narrow teeth No. 1,2,Z,8, 9,13,14,15,17,19,20,

Z9,33,34, and 36 show slight scoring below pitch

line; No. 12, 13, and 18 show rust-type stain nearfront of tooth above pitch line

30 25.20 122,400 92,459 Narrow teeth No. 2,32,34, 35, and 36 showed 11,

4, 7, 5 and 3% scuffing, respectively; wide tooth

No. 35 chipped through the plate on front face;

see Figure 53. (A detailed view of the wide gear

is shown in Figure 54.)

Test No. I terminated




(hr) (millions) Steel Titanium Condition of gear teeth

Break-in schedule

<1 0.14 73,754 55,701 Light burnishing affecting approx 1/2 of teethnear front face and 1/2 near rear face

< 1 0.42 73,754 55,701 No change

1 0.84 73,754 55,701 No change

2 1.68 80,431 60,744 Narrow teeth No. 21,22,23,24,26,27, and 32

show increased wear pattern above pitch line

near rear face; teeth No. 25,28,29,30,31,33,34,

35, and 36 same height near front

3 2.52 87,155 65,822 No change

4 3.36 93,856 70,883 No change

5 4.20 100,557 75,944 Narrow teeth unchanged; wide teeth shAw rust-

type stain near front face of No. 5

Endurance test

14 11.76 107, 276 81,018 Test rig fail'are caused loss of lubrication.

Narrow teeth No. 19, 26, 28, and 29 cracked

Test No. 2 terminated

94

Test Data--Phase I, Test No. 3,

Ac:curnulated Calculated surface


h hr) (millions) Steel Titanium Condition of gear teeth

Break-Ln sbedule

'1 0.14 75,675 57, 152 Nearly aU teeth of narrow gear had surface

irregularities near the edge breaks at front and

rear faces; wide gear was unchanged

<1 0.42 75,675 57,152 No change

1 0.84 75,675 57,1152 Rust-type stain appeared on 33 teeth of both gears,primarily near rear face

2 1.68 82, 526 62,326 Initiated scuffing near the roots of narrow teeth

No. 1,4,11,16,20,24,27,29, and 31, wide gear

satisfactory

3 2. 52 89,426 6-,537 Surface irregularities readily visible on narrow

teeth No. 5 through 17 and 32 through 36; wide

gear unchanged

4 3.36 96,301 72,729 Narrow gear relatively unchanged, scoring is

negligible; wide gear unchanged

5 4. 20 103, 177 77,922 Narrow teeth No. 5 and 28 showed minor spalling

damage to working surface near front edge break;

surface irregularities on all other teeth except

No. 6 and 33; wid2 gear unchanged. (See Figure

55 for typical gear tooth wear pattern after 4

million cycles.)

Endurance test

10 8.40 110,803 83,681 Fracture of narrow teeth No. 12 through 18; see

Figure 56. (A detailed view of the narrow gear

is shown in Figure 57.)


95

Test Data-Phase I, Test No. 4.

S;mall-scale gears



(hr) (millions) Steel Titanium Condition of goar teeth

Break-in schedule<1 0. 14 74,137 55,990 Excessive tooth wear indicated

<1 0.42 74, 137 55,990 Increased wear on all teeth

1 0.84 74, 137 55,990 Increased wear on all teeth

2 1.68 80,881 61,084 Increased wear on all teeth

2.5 2.10 87,618 66,171 Approx 507o of teeth showed misaligned tooth wear

pattern


Note: The test gears were reground to have 0. 005-in. average coating thickness.

When shotpeened, the coating came off in the nickel-rich areas of the tooth

flanks; the gears were not suitable for retesting.




(hr) (millions) S~teel Titanium Condition of gear teeth

Break-in schedule

:10 0. 14 74, 146 55,997 Narrow teeth No. 23 and 27 show nicks at tips;

wide gear unchanged

:30 0.42 74,146 55,997 Narrow teeth 14c. 3• 23, and 27 show nicks at

tips; wide gear unchanged

1 0. 84 74, 146 55,997 Unchanged

2 1.68 80,859 61,067 Narrow tooth No. 32 scored at tip; wide gear un-

changed

3 2.32 87,619 66,172 Narrow tooth No. 27 chipped through plate at OD

for two-thirds face widths from front side; wide

gear unchanged

4 3.36 94,353 71,260 Narrow teeth No. 6, 27, and 36 chipped through

plate at OD one-third, three-fourths, and two-

thirds of face width; wide gear unchanged

5 4.20 101,092 76,348 Narrow teeth No. 8 and 32 chipped through plate

at OD two-thirds and three-fourths of face width;wide gear unchanged

96

f Test Data-Phase 1, Test Na. 5, (contd)



(hr) (millions) Steel Titanium Condition of gear teeth

Endurance Test

6 --- 114,583 86,537 Narrow teeth No. 1, 4, 5, 6, 8, 10, 27, 30, 32,

33, 35, and 36 had broken tips through iron plate

at OD; wide gear unchanged7 --- 114,583 86,537 Length and width of tip breakage gradually in-

creasing; wide gear und anged

10 --- 114,583 86,537 Additional broken tips on narrow teeth No. 25 and

34; wide teeth No. 33 and 35 show axial cracks near

tip

11 --- 134,7,93 101,800 Narrow gear shows wear and scoring near root of

j i some teeth; broken tip on tooth No. S513:30 --- 134,793 101,800 Additional broken tips on narrow teeth No. 2, 14,

and 24-also increased scoring and wear; addi-tional broken tips on wide teeth No. 30 and 32

16 --- 134,793 101,800 Axial crack near tip of narrow tooth No. 3, no

other change; wide gear unchanged

17 --- 153,236 115,729 Ad.iional broken tips on narrow teeth No. 3, 11

and 12--also approxc one-third of tooth No. 36

missing; adrizonal broken tips on wide teeth No.1,4,5,28, and 29

17:24 --- 173,228 13-q,827 Complete loss of narrow tooth No. 34 (root fracture),

additional broken tips on teeth No. 9 and 16, scoringranged between 6 and 34%; wide gear relatively un-

changed


97

Test. Data-Phase II, Test No. 1,

Accuwgulated

Time cycles Hertz stress (psi)

(hr) (X 106) Steel Titanium Condition of the gear teeth

1 0.14 76, 430 60,000 Slight burnishing below pitch line on most teeth,

wear-in pattern

1 0.84 79,430 60,000 No change

2 1.68 79,430 60,000 Wear-in pattern slightly more pronounced, no

scuffing

4 3.36 92,650 70,000 No change

6 5.04 105,010 80,000 Wear-in pattern irdicatesirome misalignment ofgears; test terminated before any observable

damage to gear teeth

Test Data-Phace II, Test No. 2,

Accumulated


(hr) (x 106) Steel Titanium Condition of the gear teeth

1 0. 14 79,430 60,000 Slight burnishing below pitch line on most teeth,normal wear-in pattern

1 0.84 79,430 60,000 No change

S1.68 79,430 60,000 Wear-in pattern slightly more pronounced, no

scuffing

4 3.36 92,650 70,000 No change

6 5.04 o$bt 9!0 80,000 Narrow No. 7-19: fretting stains no change in

wear-in pattern

8 6.72 119,155 90,,000 N 8-12, 15-17, 19, 20: fretting stains. Indication

of light scuffing above pitch line on numerous

teeth

10 8.40 132.385 100,000 N 4-20: fretting stains: no increase in scuffing

patterns

Endurance Test

12.5 10.50 145,640 110,000 N 3-19: fretting stains; N 6, 12, 15, 19: axial cracks

above pitch line. N 7: plating missing from tip of

tooth. The test terminated before further damage to

narrow gear. No damage observed on wide gear

98

Test Data-Phase II, Test No. 3,

Accumulated


(hr) (X 106) Steel ritanium Condition of the gear teeth

Break-in schedule

L-1 0.14 79,430 60,000 Narrow No; 1: small pit above pitch line, right

side. Narrow No. 9 - 12, 14, 18: axial cracks

above pitch line. Narrow gear 14, 18: fretting

1stains

1 0.84 79,430 60,000 N 1: no change• N 4-14, 18: axial cracks N3, 11, 12, 14, 15;

fretting stains

2 1.68 79,430 60,000 N 1: no change

N 4-14: axial cracksN 1-21: fretting stains

, IN 11-15, 18, 19: contact in root area

4. 3.36 92,650 70,000 NI: no change

N 4-14, 17, 18: axial cracksN 3-7, 11, 13: fretting strains

6 5.04 105,910 80,000 N 1: no change

N 4-14: axial cracks

N 1-14, 21. fretting stains

8 6.72 119,155 90,000 N 1: no change

N 4: small chip of plate missing from right margin

above pitch line

N 4-14: axial cracksN 1-14, 21: fretting stains

10 8.40 132,385 100,000 N 1: no change

N 4: no change

N 4-14: axial cracks

N 1-14, 21: fretting stains

Endurance

12.3 .0.33 145, 640 110,000 Test terminated because of loss of plating

from all narrow and wide teeth

99

Test Data-Phase I1l, Test No. 1,

Accu=mdated Calculated surface

Time cycles stress levels (psi-)

(b4r (X( 106) Steel Titanium Condition of yesteeth

1 0-. 14 79,430 60,000 Some burn-ishing beow PD

1 . 84 79,430 60.000 Test gear wandered on drive shaft after the zero-

torque drive shaft nut backed of. Plaingon ge2r

teeth appears to be distressed, but not con-

sidered to be sz-fing damage

Tet No.. 1 T-,rnaed

Test Data-Phase III, Test No. 2,

A.ccumulaed Calculated surface

Time ccles' st-ress levels (psi)

(E.r) (X 106) Steel Titanium Condition of oear teeth

<1 0.14 79,430 60.000 Plate cr.,.cked on four teeth after the zero-'orque

drive shaft nut again backed off

Test No. 2 Terminated

Test Data-Phase III, Test No. 3,



(hr) (X 106% Steel Titanium Condition of gear teeth

C1 0. 14 79,430 60,000 Light burnishing below PD

<1 0.28 79,430 60,000 No change

<1 0.42 79,430 60,000 No chan-re1 0.84 79,430 60,000 No change

2 1.68 79,430 60,000 No change4 3.36 92,650 70,000 No change

6 5. C4 105,910 80,000 No ceange

8 6.72 119,155 90,000 N-- change10. 0 8.40 132,385 100,000 Teeth 8-13 show initial scuffing (0. 6%)

12. 5 10. 50 145,640 110,000 Significant scuffing all teeth; heaviest on 5, 7-12,21 (21%). Test oil flow increased to 1600 ml/min.,

auxiliary oil cooler installed

13.7 11.51 145,640 110,000 Minor scuffing increese to .23%"

100

Test Data-Phase III, Test No. 3



(hr) (X 10-) Steel Titari-am Condition 6 fe_- teeth

15,0 12.60 145,640 119,.000 &Minor scuIng increase to 252.

17-5 14.70 145,640 110,000 No cbange

20.0 16.80 145,640 i10I.00 Sc-- increase to 20j

21-2 17.81 153,875 120,000 Scuffing increase to 33%

22.5 18.90 158,875 120,600 No change

23-5 19.74 158,875 120,000 No cbange

25.0 21.00 158,875 120,000 Moderate increase in scuffing (36%)27. 5 23.10 158,875 120,000 Cracked plating on tooth No. 7. Moderate in-

crease in scuffing of other teeth (40%)

Test s _spended briefly, and then-restarted after nondestructive metallurgical

examination.

27.7 23.27 158,875 120, 000 Cracked plating on tooth No. 7 shows burnishing.

No increase in average scuffing rate (40%)

29.2 24.53 158,875 120,000 Cracked platin: on tooth No. 7 separated along

left edge. Face of mating tooth on driven gear

shows heavy damage, and adjacent teeth show

extensive scuffing. Average scuffing of teeth on

test gear shows sudden increase (75Q)

Test No. 3 Terir inated

Test Data-Phase III, Test No. 4



(hr) (X 106 Steel Titanium Condition of gear teeth

<1 0.14 79,430 60,000 Gear teeth were honed prior to lube coating.

Average scuffing was 51 after initial run.

<1 0.42 79,430 60,000 No change

1 0.84 79,430 60,000 No change

2 1.68 79,430 60,000 No change

4 3.36 92,650 70,000 No change

6 5.04 105,910 80,000 No change

8 6.72 119,155 90,000 Average scuffing was 6%

10 8.40 132,.385 100,000 No change

101

Test Data-Phase M1., Test No.. 4. (coatc)

Accunuled CalcuEaed surace


(hr) (;K IA~ Steel Titauium Conditiomnof gear teeth

15 12.60 145,640 110,000 No ha•ge

19.5 16.38 14,5.640 110,000 Testin wa• eerted when the tea

indiated a su!ena c~mage in the gear, overaffo-L

Visual etazriiationi revealed that the test gear

bad f.-actured from the root radius between teeth

No. 6 & 7 to the root radius of"a spWine at !he gear

hub -

Test No. 4 Terminated'

I

Test Data-Phase II, Tes. No., 5

Accumulated Calcullted-surface.


(hr) (x I0O) Steel Titanium Conditiori of gear teeth

<1 0. 14 79,430 60,000 Gear teeth wvere honed prior to lube coating.

Average scuffing after initial run was

<1 0.42 79,430 60,000 No change

1 0.84 79j430 60,000 No change


4 3.36 92,650 70,000 No change

6 5.04 105,-910 .80,000 No change

8 6.72 119,155. 90,000 No change


12.5 10. 50 145,640 110,000 Average scuffing increase to 91

20.0 16.80 145,640 110,000 Average scuffing was 11%o

21.7 18.19 i58,875 120,000 Testing was interrupted when the instrumentatiohi

indicated a sudden change in gear operation. Visualexamination revealed that test gear tooth No. 7 had

fractutred from the gear. The broken tooth did not

appear to be deformed. The average scuff rate on-

the remaining 20 teeth was 17-7

Test No. 5 Terminated

102 ..

LLTest DabL-Phase ME, Testlvo. 6

AccbIaed C*3kmizted S!face

CK (hGS1E) Ree TimmOr ___ ___ Ceimfru= of gear teejm

2 1.L68 79, 430 60,0W0 Awera~ge scuffing mas 34 3-36 -02,650 70.000 No dhappge

-5 5- W- 10 5,09 10 W.000~ Aw-e'rage scufing was 4

- 61219,15 C30,!O 2iui~~z1o e~e htapoi~t25% of the plate on the face of No.. IS tooth was

missfing. The average scuffng of the other

teet-h was stifl 4%

-Test No~. 6 Terminated

4

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Documents

DISTRIBUTED BY: National Technical Information Service U. S. … · General Motors Corporation Prepared for: Air Force Aero Propulsion Laboratory December 1972 DISTRIBUTED BY: National