Activities in liquid Fe-V-O and Fe-B-O alloys
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(l,
s a t u r a t e d with oxide)
Cr-Cr2Os(s) ] ThO2(Y2Os) t F e - V - O (l, s a t u r a t e d with oxide) Cr-Cr2Os(s) j ZrO~(CaO) I F e - B - O (/, B~O3 s a t u r a t e d with Alg)s) The s o l u b i l i t y of oxygen in F e - V a l l o y s at 1600~ d e c r e a s e s with i n c r e a s i n g v a n a d i u m content to a m i n i m u m of about 180 ppm at 3 wt pct V, and then i n c r e a s e s to over 4000 ppm at 36.3 wt pct V. Vanadium was found to d e c r e a s e the activity coefficient of oxygen and the value of the i n t e r a c t i o n coefficient e o(V) at infinite dilution of v a n a d i u m is - 0 . 1 4 . The activity of v a n a d i u m was c a l c u l a t e d f r o m the m e a s u r e d e l e c t r o m o t i v e force, and log VV was found to be r e p r e s e n t e d well by the q u a d r a t i c f o r m a l i s m for N v < 0.4: 2 log ~V = - 0 . 7 0 N F e - 0.30 At 1550~ b o r o n d e c r e a s e s the s o l u b i l i t y of oxygen down to about 80 ppm at 0.67 wt pct B in F e - B m e l t s in e q u i l i b r i u m with B203 s a t u r a t e d with A12Os (NAlzO3 = 0.087). The b o r o n deoxidation product, K ' = (wt pct B)2(wt pct 0) 3 at infinite dilution of b o r o n is 4.4 • 10 -9 and 1.5 • 10 -9 at 1550 ~ and 1600~ r e s p e c t i v e l y . B o r o n d e c r e a s e s the a c t i v i t y coefficient of oxygen in liquid i r o n , and the value of the i n t e r a c t i o n coefficient e~B) is - 2 . 6 at infinite dilution of boron. The activity coefficient of boron at infinite dilution (TB) is 0.083 at 1550~
THE
c h e m i c a l b e h a v i o r of oxygen in F e - V a l l o y s has b e e n the s u b j e c t of n u m e r o u s i n v e s t i g a t i o n s . However, t h e s e i n v e s t i g a t o r s have r e p o r t e d a s i g n i f i c a n t l y wide r a n g e of v a l u e s for the i n t e r a c t i o n coefficient e o(V) e (V) d(log fo) o = d(wt %V)
[1]
D a s t u r and Chipman, 1 Schenck and S t e i n m e t z , 2 and P a r g e t e r 3 e q u i l i b r a t e d F e - V a l l o y s c o n t a i n i n g up to 1.3 pct V with h y d r o g e n - w a t e r vapor m i x t u r e s at 1600~ and
r e l a t i v e to solid boron.
v a r i e d f r o m 1 • 10 -9 to 2.6 x 10 -8 b e t w e e n 1550 ~ to 1690~ D e r g e took 4 x 10 -9 as the a v e r a g e value of K ' . T h e r e has been no d e t e r m i n a t i o n of the activity coeff i c i e n t of b o r o n in liquid i r o n or of the effect of boron on the a c t i v i t y coefficient of oxygen in liquid iron. It is 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 to d e t e r m i n e the s o l u b i l i t y of oxygen and the a c t i v i t i e s in F e - B - O and F e - V - O alloys. The activity of oxygen in the a l l o y s was m e a s u r e d with the following g a l v a n i c cells:
c a l c u l a t e d e o(V) to b e - 0 . 2 7 , - 0 . 1 1 , a n d - 0 . 2 9 , r e s p e c tively. F i s c h e r and H a u s s m a n n 4 d e t e r m i n e d e_(V) o elec-
Cr-Cr2Os(s)[ ZrO2(CaO) I F e - V - O (l, s a t u r a t e d with oxide)
[I]
t r o c h e m i c a l l
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