THE STUDY OF SCORING AND SCUFFING ON LUBRICATED SLIDING SURFACES BY MÖSSBAUER SPECTROSCOPY

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THE STUDY OF SCORING AND SCUFFING ON LUBRICATED SLIDING SURFACES BY

MÖSSBAUER SPECTROSCOPY

T. Cranshaw, R. Campany

To cite this version:

T. Cranshaw, R. Campany. THE STUDY OF SCORING AND SCUFFING ON LUBRICATED

SLIDING SURFACES BY MÖSSBAUER SPECTROSCOPY. Journal de Physique Colloques, 1979,

40 (C2), pp.C2-589-C2-591. �10.1051/jphyscol:19792205�. �jpa-00218584�

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JOURNAL DE PHYSIQUE Colloque C2, suppldment au n o 3, Tome 40, mars 1979, page C2-589

THE STUDY OF SCORING AND SCUFFING ON LUBRICATED SLIDING SURFACES BY B Y O S S B A U E ~ SPECTROSCOPY

T.E. Cranshaw and R.G. campanyi

Nuclear P h y s i c s D i v i s i o n A. E. R. E., H a m e l l , O x f o r d s h i r e , OX11 OR?, England ' ~ h o m t m Research Centre, S h e l l Research Ltd., C h e s t e r , England.

Ri5sumb.- Nous d d c r i v o n s l a mise e n d v i d e n c e p a r C.E.M.S. de m a r t e n s i t e , de c d m e n t i t e e t d ' a u s t b n i t e 1 l a s u r f a c e d l Q c h a n t i l l o n s soumis 1 d e s t e s t s d ' u s u r e . Nous montrons que l ' a p p a r i t i o n de r a y u r e s e s t a s s o c i E e 1 c e l l e de l a c E m e n t i t e e t que l e g r i p p a g e e s t 2 c o r r E l e r a v e c l a prEsence d ' u n mElan- ge d ' a u s t d n i t e e t de m a r t e n s i t e . Nous a p p o r t o n s q u e l q u e s arguments e n f a v e u r d ' u n e d b c o m p o s i t i o n du p r o d u i t l u b r i f i a n t .

A b s t r a c t . - E s t i m a t i o n by C.E.M.S. o f m a r t e n s i t e , c a r b i d e and a u s t e n i t e i n w e a r s u r f a c e s i s d e s c r i - b e d . I t i s shown t h a t s c o r i n g i s a s s o c i a t e d w i t h t h e p r o d u c t i o n o f c a r b i d e on t h e s u r f a c e , and s c u f f i n g w i t h a deformed m i x t u r e o f a u s t e n i t e and m a r t e n s i t e . Some e v i d e n c e o f breakdown o f t h e l u - b r i c a n t i s p r e s e n t e d .

I n t o d u c t i o n . - The o b j e c t o f t h i s work was t o i d e n - t i f y t h e s u r f a c e c h a n g e s t h a t o c c u r d u r i n g t h e f a i - l u r e o f l u b r i c a t e d components. F a i l u r e s u r f a c e s f o r e x a m i n a t i o n were produced i n a David Brown Two D i s c machine. The d i s c t e s t s were r u n c o n t i n u o u s l y w i t h l o a d i n c r e m e n t s a t f i v e m i n u t e i n t e r v a l s u n t i l s c u f - f i n g was d e t e c t e d by a s h a r p r i s e i n f r i c t i o n and d i s c t e m p e r a t u r e , u s u a l l y accompanied by a r i s e i n n o i s e and v i b r a t i o n . " S c u f f i n g " i s an a b r u p t f a i l u r e which h a s b e e n d e f i n e d a s " g r o s s damage c h a r a c t e r i - zed by t h e f o r m a t i o n o f l o c a l w e l d s between s l i d i n g s u r f aces". The t r a n s f o r m e d s u r f a c e a p p e a r s w h i t e i n e t c h e d s e c t i o n s , and h a s b e e n c a l l e d WII by Rogers / I / . E x a m i n a t i o n by t r a n s m i s s i o n e l e c t r o n microsco- py and X-ray d i f f r a c t i o n s u g g e s t e d t h a t t h e l a y e r was a h e a v i l y deformed m i x t u r e o f a u s t e n i t e and m a r t e n s i t e .

Some d i s c s a l s o showed r e g i o n s o f h i g h po- l i s h . Under m i c r o s c o p i c e x a m i n a t i o n , t h e s e s u r f a c e s c a l l e d " s c o r e d s u r f a c e s " , show s t r e a k s i n t h e d i r e c - t i o n o f s l i d i n g and s e c t i o n s t h r o u g h t h e s u r f a c e show a t h i n t r a n s f o r m e d l a y e r . T h i s i s i d e n t i f i e d a s t h e m a t e r i a l c a l l e d W I by Rogers.

C o n v e r s i o n e l e c t r o n s p e c t r a were t a k e n o f t h e s p e c i m e n s , u s i n g a c o n v e n t i o n a l c o n s t a n t a c c e - l e r a t i o n s p e c t r o m e t e r and p r o p o r t i o n a l c o u n t e r w i t h He.CH9 f i l l i n g .

R e d u c t i o n o f d a t a . - The s p e c t r a w e r e a n a l y s e d w i t h t h e a i d o f a l e a s t s q u a r e s f i t t i n g program. I n ge- n e r a l , t h r e e components due t o ( i ) m a r t e n s i t e , ( i i ) i r o n c a r b i d e and ( i i i ) a u s t e n i t e c a n b e r e c o g n i z e d i n t h e s p e c t r a . I n e a c h component, t h e l i n e s a r e

found t o b e somewhat b r o a d e n e d . I n t h e c a s e o f t h e a u s t e n i t e , t h e b r o a d e n i n g c a n b e a t t r i b u t e d t o d i s - s o l v e d c a r b o n , p r o d u c i n g a q u a d r u p o l e s p l i t c o n t r i - b u t i o n , and i n t h e f i t t i n g program, a s i n g l e l i n e and a q u a d r u p o l e d o u b l e t w e r e a s s i g n e d t o t h i s com- p o n e n t . Using t h e e x p r e s s i o n

c = 1 / 6 q / ( q + 1 )

where c i s t h e c a r b o n c o n c e n t r a t i o n , and q and 1 a r e t h e i n t e n s i t i e s o f t h e d o u b l e t and s i n g l e t c o r n p o n e n t s r e s p e c t i v e l y , c o n s i s t e n t v a l u e s f o r t h e c o n c e n t r a t i o n o f d i s s o l v e d c a r b o n c o u l d b e o b t a i n e d p r o v i d e d t h a t t h e i n t e n s i t y o f t h e component was g r e a t e r t h a n a b o u t 15 Z.

I n t h e a b s e n c e o f a good model f o r t h e broa- d e n i n g o f t h e o t h e r components, a m o d i f i e d p(H) program was d e v e l o p e d . I n t h i s program, t h e v a l u e s o f p(H) a r e assumed t o b e non z e r o f o r HI < H < H

my and f o r t h e s e v a l u e s o f H, p(H) i s r e p r e s e n t e d by a c u b i c s p l i n e w i t h k k n o t s , e q u a l l y s p a c e d between Hl and Hm. L a r g e r v a l u e s o f k a l l o w t h e f u n c t i o n p(H) t o change more s h a r p l y . I n p r a c t i c e , k = 5 was found t o b e s u f f i c i e n t . Any number o f i n t e r v a l s over which p(H) i s f i n i t e c a n be c h o s e n , and i n e a c h i n - t e r v a l , t h e i s o m e r s h i f t i s assumed t o b e a l i n e a r f u n c t i o n o f H. C l e a r l y , i n t h e p r e s e n t c a s e , two i n t e r v a l s , one f o r t h e m a r t e n s i t e , and o n e f o r t h e c a r b i d e may b e n e e d e d .

Even w i t h a 100 mCi "CO s o u r c e , t h e c o u n t r a t e was o f t e n low, and two d a y s were needed t o o b t a i n a s p e c t r u m . To d e r i v e a n e s t i m a t e o f t h e e r r o r i n t h e a n a l y s i s due t o s t a t i s t i c a l f l u c t u a - t i o n s , t h e f o l l o w i n g method was u s e d . F i r s t a f i t

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792205

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C2-590 JOURNAL DE PHYSIQUE

was made t o t h e s p e c t r u m u s i n g t h e numbers a s r e c o r - ded. Then a s e t o f t w e n t y new s p e c t r a were g e n e r a t e d by a d d i n g t o e a c h number a random number c h o s e n such

t h a t i t s v a r i a n c e was t h e o b s e r v e d number. Each o f t h e s e new s p e c t r a were f i t t e d , and t h e s t a n d a r d de- v i a t i o n o f t h e s e t o f p a r a m e t e r s u s e d a s a n i n d i c a - t i o n o f t h e p r o b a b l e e r r o r on t h e v a l u e s f o r t h e o r i g i n a l spectrum.

R e s u l t s . - T a b l e s I and I1 g i v e t h e r e s u l t s f o r t h e s c u f f e d and s c o r e d s u r f a c e s r e s p e c t i v e l y , w h i l e f i - g u r e 1 g i v e s examples o f t h e s p e c t r a . I n a l l c a s e s , t h e s o l i d l i n e i s t h e l e a s t s q u a r e s f i t .

D i s c u s s i o n . - The p(H) d i s t r i b u t i o n s f o r t h e marten- s i t e shown i n t h e f i g u r e s a r e c o n s i s t e n t w i t h t h e well-known b e h a v i o u r o f i r o n a l l o y s ; n e a r l y a l l i m p u r i t i e s p r o d u c e a component w i t h a f i e l d a b o u t 6 % s m a l l e r t h a n t h e p u r e i r o n f i e l d . The d i s t r i b u - t i o n f o r t h e c a r b i d e component i s more s u r p r i s i n g . The main peak a t 195 kOe a g r e e s w e l l w i t h t h e f i e l d i n p u r e Fe3C, b u t components w i t h f i e l d s a s s m a l l a s

150 kOe seem t o b e p r e s e n t . These may b e due t o c a r - b i d e s i n a f i n e l y d i v i d e d s t a t e , o r i n which some o f t h e i r o n h a s b e e n s u b s t i t u t e d by a n i m p u r i t y .

I n a l l specimens c o n t a i n i n g W I m a t e r i a l ,

Spectra I

1

Î Î Î ¹ Î Î ¹ ^{, I} Î

6 L 2 0 2 L 6 " 250 350' 120 220

Velocity (mm s -' ¹

^{H e f r}

^{( k} ^0,)

F i g . 1 : Specimen s p e c t r a o f wear s u r f a c e s by C.E.M.S. The l e t t e r s A-D i d e n t i f y t h e samples i n t a b l e s I and 11. A t t h e r i g h t a r e t h e p(H) d i s t r i b u t i o n s d e t e r - mined by t h e computer program.

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c a r b i d e was o b s e r v e d i n t h e Mijssbauer spectrum, and d e v a s t h e n found i n t h e s c o r e d a r e a s .

i n t h e more u n i f o r m l y p o l i s h e d d i s c s , 50 % of t h e The v e r y h i g h c a r b o n c o n t e n t i n t h e s c o r e d s u r f a c e was i r o n c a r b i d e . s u r f a c e g i v e n i n t h e l a s t column of t a b l e I1 sug- That s c o r i n g p r e c e d e s s c u f f i n g was shown by i n t e r - g e s t s breakdown ~f t h e l u b r i c a n t i n t h e s c o r i n g r u p t i n g a d i s c t e s t b e f o r e s c u f f i n g f a i l u r e . Carbi- phase of t h e t e s t .

T a b l e I : R e s u l t s of MEssbauer s p e c t r o s c o p y o f s c u f f e d s u r f a c e s

1 . S p e c t r a o b t a i n e d from d i s c i n which t h e whole of 2 . S p e c t r a o b t a i n e d o n l y from s c u f f e d a r e a . t h e r e g i o n a n a l y s e d was s c u f f e d and c o n t a i n e d

b o t h W I I and W I m a t e r i a l . 3 . S p e c t r a o b t a i n e d from r e g i o n c o n t a i n i n g some s c u f f e d a r e a s and undamaged d i s c s u r f a c e . T a b l e I1 : R e s u l t s o f Miissbauer s p e c t r o s c o p y of s c o r e d s u r f a c e s

Running c o n d i t i o n s S l i d i n g

s p e e d m.s-1

Wossbauer r e s u l t s

1. C a l c u l a t e d assuming o r i g i n a l c a r b o n c o n t e n t f o r 2 . Base o i l c o m p o s i t i o n -0.95 % w s u l p h u r : a d d i t i - m a r t e n s i t e , i . e . 4 a t o m i c %, 25 a t o m i c % c a r b o n ve

-

z i n c d i a l k y l d i t h i o p h o s p h a t e t y p e .

f o r c a r b i d e and i n d i c a t e d c a r b o n c o n t e n t f o r a u s t e n i t e .

M a r t e n s i t e 7.w

(11) 87

(a)

97

10 5 0

(c)

74 78

Running conditions Mossbauer results

R e f e r e n c e s

/ 1 / Rogers, M.D., T r i b o l o g y

2

(1969) 123.

R o l l i n g s p e e d m.s-1

C a r b i d e Zw

0 0

26 0

0 0

un-run a s ground

ground and l i g h t l y p o l i s h e d O i l

temp.

OC

. 5 l 5

Y

33 5

carbide Xw 4 9 2 3 32 2 2

30 3 5 2 1 6 6 2 2 1 6 ~ 1 5

A u s t e n i t e

%w

13 3

61 50

26 22

85

35 85 8

Oxide

%w

- -

3

- -

S u r f a c e r o u g h n e s s

u i n c l a

Austenite Zw 2 0 2 2 20 2 2

I9 4 1 2 1 1 8 2 1 2 3 2 1 A d d i t i v e

'Ontent

8 8 8 8

16

5

16

I , ! ^{( 1}

i

8 5 35 35

35

16 5 5 5

Atomic % C in Austenite

4.5 5.0

5.3 6.6

5 . 0

5.4 3x13

I ' I

I

0 0

0.5

0

5 0.5

"

Oxide Xv

I

2

2 I

Overall atomic percent

14.3 10.9

14.7 12.3 13.6 7.7 slow

fast

slow fast slow fast

2 9 2 1

(3)47 2 2 30 2 2 2 1 3 4 2 2 6 1 2 2