WEAR

OF

GLASS-REINFORCED

AGGRESSIVE

PLASTICS

IN

MEDIA

V . S. G u m e n y u k , G. A. a n d S. D. L e k h m a n

Kulinskii,

UDC 539.5:539.~;2

The effect of c e r t a i n a g g r e s s i v e m e d i a on the w e a r of g l a s s - r e i n f o r c e d p l a s t i c s has been inv e s t i g a t e d . It is shown that as the angle of inclination of the g l a s s r e i n f o r c i n g f i b e r s r e l a t i v e to the friction s u r f a c e i n c r e a s e s , the w e a r of the m a t e r i a l is s h a r p l y reduced.

The m e t a l a r t i c u l a t i o n s of c e r t a i n a g r i c u l t u r a l m a c h i n e r y n o r m a l l y in direct contact with a g g r e s s i v e m e d i a such as p e s t i c i d e s , m i n e r a l f e r t i l i z e r s , and silage, a r e subject to s e v e r e c o r r o s i o n and s u r f a c e w e a r . In o r d e r to p r e v e n t this it is d e s i r a b l e to combine m a t e r i a l s of different kinds, for e x a m p l e , m e t a l s and p o l y m e r s , in p a r t i c u l a r g l a s s - r e i n f o r c e d p l a s t i c s which have a s e r i e s of valuable p r o p e r t i e s - high m e c h a n ical strength, low density, r e s i s t a n c e to a g g r e s s i v e m e d i a , damping capacity, simple fabrication, e!Lc. [1-3]. However, the w e a r r e s i s t a n c e of g l a s s - r e i n f o r c e d p l a s t i c s u n d e r sliding friction conditions has not been sufficiently studied and the published data a r e c o n t r a d i c t o r y . It is usually a s s u m e d that g l a s s - r e i n f o r c e d p l a s t i c s have low w e a r r e s i s t a n c e ; at the s a m e t i m e , it has been r e p o r t e d [4] that the w e a r r e s i s t a n c e of a p o l y e s t e r g l a s s - r e i n f o r c e d plastic is four t i m e s g r e a t e r than that of s t e e l 45. Below we p r e s e n t the r e s u l t s of an investigation of the effect of c e r t a i n a g g r e s s i v e m e d i a on the w e a r of g l a s s - r e i n f o r c e d p l a s t i c s operating in combination with a m e t a l . The g l a s s s t r a n d s used in winding the g l a s s - r e i n f o r c e d plastic ring s p e c i m e n s w e r e i m p r e g n a t e d with E B F g r a d e e p o x y - b u t v a r - p h e n o l i c r e s i n . F r o m t h e s e rings we cut s e c t o r - s h a p e d s p e c i m e n s . F o r c o m p a r i s o n we investigated the w e a r of SCh18-36 c a s t iron and s t e e l 3. As the o t h e r m e m b e r of the t e s t p a i r we used rings of s t e e l 45 with a c l a s s ~7 7 finish. The s p e c i m e n s w e r e cleaned and dried for 1 h at a t e m p e r a t u r e of 105-110°C and then weighed on a m i c r o b a l a n c e . The w e a r was studied u n d e r d r y friction conditions, in water, in a 25%aqueous solution of a m m o n i a , and in t h e s e p e s t i c i d e media: N u v a r c r o n 20 (Swiss), DDVP, and m - x y l e n e . The sliding speed could be v a r i e d between 0,,2 and 5.0 m / s e c and the p r e s s u r e between 0.5 and 20.0 k g f / c m 2. The a g g r e s s i v e liquids were supplied to the friction zone by i m m e r s i n g the bottom of the m e t a l m e m b e r of the friction p a i r in a bath filled with the m e d i u m . The w e a r of the u n r e i n f o r c e d epoxy r e s i n u n d e r d r y friction at a specific load of 10 k g f / c m 2 was 8 m m 3 / k m (Fig. l a ) . The p r e s e n c e of a g g r e s s i v e m e d i a in the friction zone tends to reduce the p o l y m e r w e a r . The w e a r of the g l a s s - r e i n f o r c e d p l a s t i c with f i b e r s running p a r a l l e l to the friction s u r f a c e differs only slightly f r o m that of the u n r e i n f o r c e d epoxy c o m p o s i t i o n (Fig. lb). When the f i b e r s a r e oriented at right angles to the friction s u r f a c e the w e a r of the g l a s s - r e i n f o r c e d p l a s t i c is s h a r p l y reduced (by a f a c t o r of 12, Fig. lc). As a r e s u l t of studying the w e a r of the g l a s s - r e i n f o r c e d p l a s t i c at i n t e r m e d i a t e angles of the f i b e r s r e l a t i v e to the friction s u r f a c e we obtained a relation s i m i l a r to that shown in Fig. 2. At large angles of inclination of the glass f i b e r s , which have low w e a r r e s i s t a n c e , the g l a s s s u r f a c e in d i r e c t contact with the m e t a l is reduced; a c c o r d i n g l y the w e a r is also reduced. At an angle of inclinaUkrainian A g r i c u l t u r a l A c a d e m y , Kiev. T r a n s l a t e d f r o m Mekhanika P o l i m e r o v , No. 2, pp. 364-366, M a r c h - A p r i l , 1974. Original a r t i c l e s u b m i t t e d June 20, 1973.

© 19 75 Plenum Publishing Corporation, 22 7 West 17th Street, New York, N. Y. 10011. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission o f the publisher. A copy o f this article is available from the publisher for $15.00.

307

/

6.o a

2

N *,S E 3,0 o)

2

*

8 P, kgf/crn 2 ! o,5

c

2

E o,3 E

3

©

0.2 o,t

0

2

0

r

0

6p, kgf/cm 2

2

z~ g

.

8

I0 p, kgf/cm~ !

2,O

E E

¢o

~: /,o

Q)

2

. . . . . 2 ~ 6 8 p, kgf/cm ~

o

2

~

6

Op, kgf/cm ~

F i g . 1. W e a r o f t h e u n r e i n f o r c e d e p o x y c o m p o s i t i o n (a), g l a s s - r e i n f o r c e d p l a s t i c w i t h f i b e r s p a r a l l e l to t h e f r i c t i o n s u r f a c e (b), g l a s s r e i n f o r c e d p l a s t i c w i t h f i b e r s p e r p e n d i c u l a r to t h e f r i c t i o n s u r f a c e (c), s t e e l 3 (d), and S C h 1 8 - 3 6 c a s t i r o n (e) a s a h m c t i o n o f t h e s p e c i f i c l o a d : 1) d r y f r i c t i o n ; 2) in a m m o n i a m e d i u m ; 3) in w a t e r ; 4) in DDVP; 5) in m - x y l e n e ; 6) in N u v a r c r o u 2 0 . v = 0 . 5 m / s e e . a t i o n of 90 ° t h e s p e c i f i c s u r f a c e o f t h e g l a s s in t h e f r i c t i o n zone i s m i n i m a l a n d t h e g l a s s - r e i n f o r c e d p l a s t i c i s c h a r a c t e r i z e d by m i n i mum wear.* In d r y f r i c t i o n p o l y m e r p a r t i c l e s d i s p e r s e d a s a r e s u l t of m e c h a n i c a l d e g r a d a t i o n a r e p r e s e n t in t h e m e t a l - p l a s t i c zone w h e r e t h e y form a weak low-molecular layer and act as a lubricant.

E 2 E ©

N

0

30

60

F i g . 2. W e a r o f g l a s s - r e i n forced plastic as a function of the angle of inclination o f t h e f i b e r s r e l a t i v e to t h e friction surface (dry frict i o n ) . P = 9.5 k g f / c m 2 ; v = 0.5 /ll//sec.

308

I n F i g . l d , e f o r c o m p a r i s o n we h a v e p l o t t e d the w e a r o f S C h 1 8 36 c a s t i r o n a n d s t e e l 3. It f o l l o w s f r o m t h e r e l a t i o n s o b t a i n e d t h a t t h e w e a r o f a g l a s s - r e i n f o r c e d p l a s t i c w i t h f i b e r s p e r p e n d i c u l a r to the friction surface is more than ten times less than the wear of cast i r o n and five t i m e s l e s s t h a n t h a t o f s t e e l . C o m p a r i n g t h e r e l a t i o n s o b t a i n e d , we a l s o n o t e t h a t t h e w e a r of a l l t h e m a t e r i a l s i n v e s t i g a t e d i n c r e a s e s with p r e s s u r e , p a r t i c u l a r l y * T h e t e s t s w e r e t o o s h o r t (30 r a i n s ) t o d e t e c t w e a r of t h e m e t a l w h o s e surface was much greater than that of the test specimen.

in dry friction. F o r the r e i n f o r c e d p o l y m e r this p r o c e s s is stabilized on the load range investigated - in this case it would seem that the s t r u c t u r a l changes at the p o l y m e r friction surface are completed m o r e rapidly. Another c h a r a c t e r i s t i c shared by all the m a t e r i a l s investigated is the sharp fall in wear in the above-mentioned media, which evidently act as lubricants.

LITERATURE 1.

2. 3. 4.

CITED

A. P. Begidzhanova and P. M. Kreidlin, in: Applications [in Russian], Moscow (1970), p. 163. A. M. Kogan, L. I. Koshkin, Kh. R. Parksheyan, and I. V. Plastic Production and Use [in Russian], Moscow (1972), V. S. Gumenyuk and V. V. Lushchik, Mekhan. Polim., No. M. Zh. Dyusushe, Proc. Ufa Petrochem. Sci.-Res. Inst.

of Plastics in Tractor Machine-Building Rakhlin, in. Economics of Glass-Reinforced p. 7. 4, 757 (]967). [in Russian], Vol. 21,Ufa (1969), p° 117.

309