Electrotransport of carbon, nitrogen, and oxygen in zirconium
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The e l e c t r o t r a n s p o r t v e l o c i t i e s of c a r b o n , n i t r o g e n , and oxygen in z i r c o n i u m were d e t e r m i n e d at 1625 ~ 1700 ~ and 1800~ Diffusion c o e f f i c i e n t s and effective c h a r g e s were c a l c u l a t e d for each of these e l e m e n t s at the s a m e t e m p e r a t u r e s . The diffusion coefficients in c o m b i n a t i o n with the m i g r a t i o n v e l o c i t i e s were used to p r e d i c t the m e a n c o n c e n t r a t i o n profile of z i r c o n i u m rods a f t e r v a r i o u s t i m e i n t e r v a l s . The r e m o v a l of n i t r o g e n and oxygen from z i r c o n i u m was in good a g r e e m e n t with the p r e d i c t e d v a l u e s a f t e r a 5 day r u n . In c o n j u n c t i o n with this i n v e s t i g a t i o n the specific r e s i s t i v i t y of i3 z i r c o n i u m was m e a s u r e d and the s o l i d s o l u b i l i t y of c a r b o n d e t e r m i n e d .
T H E m i g r a t i o n of s o l u t e s under the i n f l u e n c e of a d i r e c t c u r r e n t has b e e n known s i n c e 1928.1 T h e r e has b e e n a r e n e w e d i n t e r e s t in this p h e n o m e n o n in the last ten y e a r s and s e v e r a l r e v i e w a r t i c l e s have b e e n publ i s h e d on the s u b j e c t . 2-6 R e c e n t l y it has b e e n d e m o n s t r a t e d to be an e x c e l l e n t method of p r e p a r i n g s m a l l a m o u n t s of high p u r i t y r e f r a c t o r y m e t a l s . 7-1~ In 1940 DeBoer and F a s t 11 r e p o r t e d that oxygen m i g r a t e s toward the anode in z i r c o n i u m when a dc c u r r e n t is p a s s e d through it at e l e v a t e d t e m p e r a t u r e s . T h i s was l a t e r s u b s t a n t i a t e d by Claudson. 12 The p u r p o s e of the p r e s e n t i n v e s t i g a t i o n was to d e t e r m i n e the m i g r a t i o n v e l o c i t i e s of c a r b o n , n i t r o g e n , and oxygen in z i r c o n i u m and to obtain c o m p l e m e n t a r y data on t h e i r a p p r o x i m a t e diffusion coefficients and effective c h a r g e s . The t r a n s port m o b i l i t i e s and diffusion coefficients were then 9used to p r e d i c t the c o n c e n t r a t i o n profile in a n e l e c t r o t r a n s p o r t e x p e r i m e n t of a given t i m e , c u r r e n t d e n s i t y , and s p e c i m e n length. A c o m p a r i s o n of the c o n c e n t r a t i o n profile and the p u r i f i c a t i o n that would be expected from known solute v e l o c i t i e s and diffusion coe f f i c i e n t s with that which i s obtained e x p e r i m e n t a l l y can be v e r y useful in d e t e r m i n i n g whether m a x i m u m p u r i f i c a t i o n has b e e n achieved. E X P E R I M E N T A L METHOD The e x p e r i m e n t a l m e t h o d used for this i n v e s t i g a t i o n was i d e n t i c a l to that d e s c r i b e d by P e t e r s o n e t a l . s in t h e i r work on t h o r i u m . The a p p a r a t u s and p r o c e d u r e s a r e d e s c r i b e d in d e t a i l in that pa
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