Electrochemical measurement of the diffusivity of oxygen in liquid lead
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2 , M A Y 1971
7 J R. Rellick: Ph.D. Thesis research, University of Pennsylvania, t971. S. g. E. Hopkins and H. R. Tipler: J. Iron Steel Inst.. 1958, vol. 188, p. 218. 9 P. Jolly and C. Goux: M&n. Sei. Rev. M&., 1969, vol, 66. p. 605. 10. W. P. Rees and B. E. Hopkins: J. Iron Steel h~st., 1952, wl. 172, p. 403. 11. Sec report of NMAB: .L Metals, May 1970, p. ,39. 12. G. I tenry, et al,: M~m Sci. Rer. M~t.. 1959, vol. 56, no. 4. p. 417. 13. H. L, Marcus: Science Center. North American Rockwell Corp., Thousand Oaks, Calif., unpublished research.
Electrochemical Measurement of the Diffusivity of Oxygen in Liquid Lead S. HONMA, N. SANO, AND Y. MATSUSHITA
PREVIOUSwork 1 showed
that the d i f f u si v i t y of oxygen in m e t a l s can be m e a s u r e d p o t e n t i o m e t r i c a l l y by fortowing the change of e l e c t r o m o t i v e f o r c e with t i m e due to its unsteady diffusion in a m e t a l c o l u m n , which c o n t a c t s a solid e l e c t r o l y t e only at the b o t t o m . In the p r e s e n t t n v e s t i v a t i o n , the a p p l i c a t i o n of the method to liquid lead is d e m o n s t r a t e d ; the s y s t e m is c h a r a c t e r ized by the f o r m a t i o n of no oxide on the m e t a l s u r f a c e below a c e r t a i n oxygen p r e s s u r e . The p r i n c i p l e of the m e a s u r e m e n t is s c h e m a t i c a l l y r e p r e s e n t e d in F i g . l . Oxygen c a r r i e d by ar g o n is a bs o r b e d into a liquid lead c o l u m n with length L c o n tained in an a l u m i n a tube with a solid e l e c t r o l y t e d i s c , s e c u r e l y s e a l e d with g l a s s at the b o t t o m . A s s u m i n g e q u i l i b r i u m of oxygen at the g a s - m e t a l i n t e r f a c e and diffusion c o n t r o l in the liquid m e t a l , Ficlc's second law is s o l v e d . 2
Ci-Co = 1_ 4 ~ CA-
Co
~ n=t)
(-1) n (2~[-~ 1) exp
{-D(2n + 1)~"-l } 4L='
tl] Co = hlitial c o n c e n t r a t i o n of oxygen in molten lead C, = Oxygen c o n c e n t r a t i o n in m o l t e n lead at the bottom of the coluran
CA = Oxygen
c o n c e n t r a t i o n in molten lead e q u i l i b r a t e d with a b s o r b e n t g as
/) = Diffusion c o e f f i c i e n t of oxygen in molten lead t = Time L = Length of m o l t e n lead bath Since Ni + NiO w as used for the r e f e r e n c e e l e c t r o d e , the d i f f e r e n c e between the m e a s u r e d e l e c t r o m o t i v e f o r c e and the final e l e c t r o m o t i v e f o r c e is e x p r e s s e d by Eq. [2J.
~E,
AE -
R T In Cl 2F ~AA
[2]
S. HONMA, formerly Research Assistant, Department of Metallurgy and MaterMs Science, University of Tok,jo, Tokyo, Japan, is now with 1.B.M. Japan, Ltd., Tokyo, Japan. N. SANO and Y. MATSUSH1TA are Associate Professor and Professor. respectively, Department of Metallurgy and blateriaJs Science, University of Tokyo, Tokyo. Japan. Manuscript submitted October 8, 1930. METALLURGICAL TRANSACTIONS
w h e r e t h e a p p l i c a b i l i t y of H e n r y ' s law :~ to t h i s s y s t e m is a s s u m
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