Rates of dissolution of rotating iron cylinders in liquid copper and cu-fe alloys

  • PDF / 589,907 Bytes
  • 7 Pages / 612 x 792 pts (letter) Page_size
  • 91 Downloads / 240 Views

DOWNLOAD

REPORT


H E k i n e t i c s of d i s s o l u t i o n of solids in liquid m e t a l s have b e e n studied u n d e r w e l l - d e f i n e d h y d r o d y n a m i c conditions. T h e s e s t u d i e s include d i s s o l u t i o n k i n e t i c s of Cu in Pb and Bi, 1 P b in P b - S n a l l o y s , 2 Z n in Bi, 3 Cu and Ni i n Pb, 4 Si, Ti, C r , F e , Co, and Ni in Cu, s Zn, Ag, and Sn in Hg, 6 Ni and Cu in Bi, 7 Fe in F e - C a l l o y s , 8 C in F e - C a l l o y s , 9,~~ T a in Sn, 1~ Cu in Pb, ~2 and A1 in Bi. ~3 In m o s t of these s t u d i e s , the s o l u t i o n r a t e c o n s t a n t was d e t e r m i n e d on the b a s i s of the Berthoud equation ~4 (the N e r n s t - B r u n n e r equation) or the r e l a t i o n of L o m m e l and C h a l m e r s , 2 which e x p r e s s the d r i v i n g f o r c e of d i s s o l u t i o n in t e r m s of the conc e n t r a t i o n of s o l u t e , and in some of these s t u d i e s the s o l u t i o n - r a t e c o n s t a n t was a n a l y z e d on the b a s i s of the E i s e n b e r g c o r r e l a t i o n for r o t a t i n g cylinders,~5 the C h i l t o n - C o l b u r n m a s s t r a n s f e r analogy to heat t r a n s f e r 16 or the r e l a t i o n of Levich. ~7 T h e s e s t u d i e s have shown that the d i s s o l u t i o n in m o s t of the s y s t e m s is c o n t r o l l e d by diffusion in the liquid, but that the d i s s o l u t i o n of lead in liquid P b - S n alloys is c o n t r o l l e d by a s u r f a c e r e a c t i o n at the s o l i d / l i q u i d interface,2 and that the d i s s o l u t i o n of zinc in liquid m e r c u r y 6 and that of t a n t a l u m in liquid t i n ~ a r e m i x e d c o n t r o l l e d . Shurygin and S h a n t a r i n S i n v e s t i g a t e d the r a t e of d i s solution of r o t a t i n g i r o n disks in liquid copper and on the b a s i s of the r e l a t i o n of Levich ~7 they d e m o n s t r a t e d that the p r o c e s s was c o n t r o l l e d by diffusion in the liquid. R e c e n t l y Sri K r i s h n a e t a l . ~3 i n v e s t i g a t e d the d i s s o l u t i o n of r o t a t i n g zinc single c r y s t a l d i s k s in n e a r l y s a t u r a t e d a m a l g a m s and a n a l y z e d t h e i r exp e r i m e n t a l data with a modified f o r m of the Berthoud equation e x p r e s s e d in t e r m s of zinc c h e m i c a l a c t i v i t i e s . They o b s e r v e d that the r a t e of c r y s t a l attack was i n d e p e n d e n t of h y d r o d y n a m i c conditions in the r a n g e of Reynolds n u m b e r s f r o m 20,000 to 30,000 and that the d i s s o l u t i o n p r o c e s s was s u r f a c e c o n t r o l l e d . In the t h e o r y of absolute r e a c t i o n r a t e s , the a c t i v i ties of r e a c t a n t s a r e taken into account ~sa and the d r i v i n g force of diffusion is a g r a d i e n t of the c h e m i c a l p o t e n t i a l of a diffusing substance,lSb which is a funcR. OHNO is Assistant Professor, The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai, Japan. Manu

Data Loading...