Electrotransport purification and some characterization studies of vanadium metal
- PDF / 584,064 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 3 Downloads / 200 Views
the s t a r t i n g m a t e r i a l in t h i s i n v e s t i g a t i o n . It was a r c - m e l t e d in a g e t t e r e d i n e r t a t m o s p h e r e a n d swaged into rods a p p r o x i m a t e l y 0.25 cm in d i a m . T h e s e w e r e then e l e c t r o p o l i s h e d in a m e t h a n o l - p e r c h l o r i c acid solution. The r o d s w e r e v a c u u m d e g a s s e d and r e c r y s t a l l i z e d by heating at 850~ u n d e r a p r e s s u r e of 2 • 10 -6 t o r r . The r e s i s t a n c e r a t i o of p o l y c r y s t a l l i n e r o d s p r e p a r e d and t r e a t e d in t h i s way was 150 to 190. C h e m i c a l a n a l y s e s of t y p i c a l e l e c t r o r e f i n e d v a n a dium c r y s t a l s a s r e p o r t e d by Sullivan and c o w o r k e r s a r e given in T a b l e I a s a r e those for the p u r e s t e l e c t r o n - b e a m z o n e - r e f i n e d m e t a l obtained by Reed and the a r c - m e l t e d r o d s u s e d a s the b a s e m e t a l in this investigation. S i n g l e - c r y s t a l s p e c i m e n s having a (149> o r i e n t a t i o n w e r e r e q u i r e d for the r e s o l v e d flow s t r e s s m e a s u r e m e n t s . T h e s e w e r e obtained by a n a r c - z o n e m e l t i n g t e c h n i q u e the d e t a i l s of which a r e d e s c r i b e d e l s e w h e r e . 13 C y l i n d r i c a l rods a p p r o x i m a t e l y 0.25 cm in diam by 2.5 to 5 cm in length o r i e n t e d to a (149> d i r e c tion along the a x i s w e r e cut and m a c h i n e d f r o m an a r c z o n e - m e l t e d single c r y s t a l . F o u r of t h e s e s e g m e n t s w e r e then spot welded in t a n d e m u n d e r an i n e r t gas a t m o s p h e r e , e l e c t r o p o l i s h e d and v a c u u m d e g a s s e d a s d e s c r i b e d above. as
P u r i f i c a t i o n Method The v a n a d i u m was p u r i f i e d by an e l e c t r o t r a n s p o r t t e c h n i q u e in which a c y l i n d r i c a l rod i s heated by i n t e r n a l r e s i s t a n c e c a u s i n g i m p u r i t i e s to m i g r a t e tow a r d the cathode end upon a p p l i c a t i o n of a high d e n s i t y e l e c t r i c c u r r e n t . D e t a i l s of the a p p a r a t u s and e x p e r i m e n t a l method a r e given in a p a p e r by P e t e r s o n and S c h m i d t f The s p e c i m e n was f u r t h e r d e g a s s e d p r i o r to p u r i f i c a t i o n by heating at 1400~ in the c h a m b e r for a few h o u r s u n d e r a p r e s s u r e of 5 • 10 -1~ t o r r . The
Table I. Purity of Fused Salt Electrorefined Vanadium after Different Refining or Melting Treatments
EXPERIMENTAL PROCEDURE Material D o u b l e - e l e c t r o r e f i n e d v a n a d i u m obtained f r o m the U.S. B u r e a u of M i n e s at B o u l d e r City was employed O. N. CARLSON, F. A. SCHMIDT,and D. G. ALEXANDER are Senior Metallurgistand Professor, Metallurgist,and Assistant Metallurgist, respectively, Institute for Atomic Research and Department of Metallurgy, Iowa State University, Ames, Iowa. Manuscript submi
Data Loading...
