Hot hardness of manganese selenide (MnSe)
- PDF / 317,772 Bytes
- 2 Pages / 612 x 792 pts (letter) Page_size
- 13 Downloads / 221 Views
;-
"
NICKEL STEN
Fig. 2--Taper section {20:1) of tungsten-coated alumina infiltrated with liquid gold. Surface electroplated with nickel. Unetched. Magnification 140 times.
Additional evidence for the tungsten bronze hypothesis was obtained by carrying out the coating procedure with molybdenumdisulfide. A strongly adherent disulfide coating could be produced as before but on reduction this coating was converted to a nonadherent powder. Sincemolybdenumdoes not form an analog of
Hot Hardness of Manganese Selenide (MnSe)
tungsten bronze there was no bondingagent in this latter case. Attempts at coating metallic substrates by this technique were unsuccessful, as were attempts to thicken a reduced WS2 coating by a second application and reduction of WSe on the coated surface. This tends to further strengthen the writer's view that a metal-ceramic intermediate compoundplays an essential role in the formation of the bonded coating. The microcracked tungsten coatings form an excellent basis for infiltrating the ceramic surface with liquid metal. Gold and silver were infiltrated in separate e x p e r i m e n t s in which the s u r f a c e w a s c o v e r e d with m e t a l p o w d e r and the coated s p e c i m e n then h e a t e d to 40~ above the m e l t i n g point of the m e t a l . F i g . 2 shows a t a p e r s e c t i o n of a gold i n f i l t r a t e d , t u n g s t e n c o a t e d a l u m i n a s p e c i m e n . The s a m p l e was p l a t e d with n i c k e l to f a c i l i t a t e p r e p a r a t i o n of the m e t a l l o g r a p h i c section. The w r i t e r i s indebted to the G e n e r a l E l e c t r i c C o m pany f o r p e r m i s s i o n to publish t h i s work, c a r r i e d out while he was a s s o c i a t e d with the C o r p o r a t e R e s e a r c h and D e v e l o p m e n t C e n t e r . 1. R. E. Cechand T. D. Tiemann: Trans. TMS-A1ME, 1969, vol. 245, pp. 1727-33.
V i c k e r s m a c h i n e w a s r e p l a c e d by a d e a d - w e i g h t load, c o u n t e r b a l a n c e d o v e r b a l l - b e a r i n g p u l l e y s . Depending on the t e m p e r a t u r e , loads w e r e chosen b e t w e e n 1200 and 200 g with s e n s i t i v i t i e s to l e s s than 1 pct. T h e h a r d n e s s was c a l c u l a t e d 7 a c c o r d i n g to
G. S. MANN AND b . H. VAN VLACK
PREVIOUSw o r k
by Chao e t al. ~ p r o v i d e d a c o m p a r i son between the h o t - h a r d n e s s v a l u e s of MnS i n c l u s i o n s and unalloyed f e r r i t e in s t e e l . T h o s e data c o v e r e d the t e m p e r a t u r e r a n g e of 20 ~ to 960~ F i g . l(a). T h e data w e r e i n t e r e s t i n g b e c a u s e t h e r e l a t i v e h a r d n e s s e s of the two p h a s e s h a v e a s i g n i f i c a n t effect upon i n c l u s i o n d e f o r m a t i o n and f r a c t u r e . 2 - 4 Subsequent w o r k by R i e w a l d 5 showed that the h a r d n e s s of MnSe w a s l e s s t e m p e r a t u r e s e n s i t i v e than MnS in the - 7 0 ~ to 135~ r a n g e . Although s o f t e r than MnS at a m b i e n t t
Data Loading...
