Densities and viscosities of some liquid alloys of zinc and cadmium
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A S pointed out in r e v i e w s by B r u s h ~ and W i t t e n b e r g and Ofte, 2 t h e o r e t i c a l s t u d i e s of v i s c o s i t y have had v e r y little s u c c e s s even for s i m p l e liquids like a r g o n , and even l e s s for liquid m e t a l s . Indeed, it might safely be said that knowledge of the r e l e v a n t f a c t o r s in v i s cous flow has h a r d l y a d v a n c e d despite g r e a t efforts by t h e o r e t i c i a n s . Of c o u r s e , in e a r l i e r y e a r s e x p e r i m e n tal and m a t h e m a t i c a l t e c h n i q u e s w e r e l e s s r e f i n e d than in the p r e s e n t day. T h i s lack of good t e c h n i q u e s led to rationalizations of, and deductions from, what were incorrect results as described by Thresh and Crawley.3'4 However, as discussed in an earlier paper 5 several proven and accurate methods are now available to gather reliable data. It was to. throw further light on our knowledge of liquid metals that the work reported herein was undertaken.
EXPERIMENTAL
METHOD
Materials of 99.999 pct purity supplied by Cominco Ltd., were used in this investigation. The entire alloy systems Zn-Sn, Cd-Sn, and Cd-Pb were studied while Zn-Pb alloys were measured to only 0.52 at. pct Pb and Cd-Tl to 6.56 at. pct TI. Densities and viscosities were determined up to 100 ~ to 150~ above the liquidus temperatures. Density D e n s i t i e s w e r e m e a s u r e d u s i n g an a c c u r a t e l y m a chined g r a p h i t e p y c n o m e t e r by a technique which h a s b e e n d e s c r i b e d and a s s e s s e d in e a r l i e r p a p e r s . 6-8 To l i m i t v a p o r i z a i o n and oxidation of zinc and c a d m i u m , the d e n s i t o m e t e r was o p e r a t e d u n d e r an a t m o s p h e r e of a r g o n .9 ,lo
m e t a l . The a p p a r a t u s , its d e s i g n , and o p e r a t i o n have b e e n d e s c r i b e d fully in e a r l i e r p a p e r s . 3,n P r o c e d u r e s to s u p p r e s s v a p o r i z a t i o n l o s s e s and oxidation of zinc and c a d m i u m have b e e n d e s c r i b e d p r e v i o u s l y . n " e To evaluate v i s c o s i t y coefficients f r o m raw e x p e r i m e n t a l data, the m a t h e m a t i c a l a n a l y s i s of Roscoe ~3 was used. RESULTS Density As in all p r e v i o u s work in this p r o g r a m , d e n s i t y showed a l i n e a r dependence on t e m p e r a t u r e . The exp e r i m e n t a l r e s u l t s w e r e s u b j e c t e d to a f i r s t - o r d e r r e g r e s s i o n a n a l y s i s to d e t e r m i n e the c o n s t a n t s a and b in the equation p = a + bt [1] where p = d e n s i t y in g p e r cu cm t = t e m p e r a t u r e in ~ In T a b l e I, the v a l u e s of a and b d e t e r m i n e d for the a l loys studied have b e e n l i s t e d . The r e s u l t s a r e c o n s i d e r e d to be a c c u r a t e within • pct when all r a n d o m and s y s t e m a t i c e r r o r s a r e t a k e n into account. M o l a r v o l u m e s w e r e c a l c u l a t e d f r o m the d e n s i t y data and t
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