Gas solubility measurements and the derivation of inherent thermodynamic information
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t e m p e r a t u r e and p a r t i a l p r e s s u r e of the gas, log f ~ ~ i (and/or log f N i ) v a r i e s l i n e a r l y with the mole fraCtion XCo (and'7o~ XNi). It was shown 1,6 that this l i n e a r c o n c e n t r a t i o n dependence o c c u r s if the m i x e d solvent f o r m s an ideal solution. C o n s i d e r e d on an atom f r a c tion s c a l e the n i t r o g e n s o l u b i l i t y in N i - C o - a l l o y s is even s m a l l e r , and one would expect the s a m e l i n e a r dependence of log NNi-Co on XCo. Of the two m e a s u r e m e n t s 7'8 known f r o m the l i t e r a t u r e only one 8 c o v e r s the whole s y s t e m with five p o i n t s , Fig. 1. Since the l i n e a r dependence is not c l e a r l y e s t a b l i s h e d , the n i t r o g e n s o l u b i l i t y m e a s u r e m e n t s w e r e r e p e a t e d . NiC o - a l l o y s were e q u i l i b r a t e d with n i t r o g e n gas at 1600~ quenched* and a n a l y z e d for n i t r o g e n . The r e *The authors wish to thank Dr. T. El Gammal for assistance with the experiments
s u l t s a r e given in Fig. 1. The l o g a r i t h m s of the n i t r o g e n s o l u b i l i t y in the N i - C o - a l l o y s and cobalt lie close to a s t r a i g h t line. The e x p e r i m e n t a l value for pure nickel is lower. In view of the a n a l y t i c a l diffic u l t i e s at these low n i t r o g e n v a l u e s t h i s value is o m i t t e d in e s t a b l i s h i n g the r e g r e s s i o n line through the other e x p e r i m e n t a l points. F r o m this r e g r e s s i o n line the n i t r o g e n solubility in pure n i c k e l is e s t i m a t e d 9 x o
1. T. Slot, R H. Stentz, and J. T. Berhng: Controlled-Strata Testing Procedures from the Viewpoint of High Temperature Matermls Behavior, GE-NSP report GEMP-698, May, 1969; also a chapter in Am. Soc Testing Mater., Spec Tech. Publ. No. 465, 1969.
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Gas Solubility Measurements and the Derivation of Inherent Thermodynamic Information KLAUS W. LANGE AND HERMANN SCHENCK
th~s mvest~aHon Blosse.q,R.5 , Pehl/,e , K D (1.966) 8) Blossey, g 3 ; Pch/ke, s D {19G6) 7) v S t o m e k h / n , A Ya e t a / ( 1 9 ~ 5 ) 3) @ Ageev, P. Ya , ['heenov, B 6. (r -to) llurnberf, J , Eli/oft, J. F. (1960) "11) a Sohenok,/I ei'~/ (1958) 12) 0 Aver/n, VV ctd ( 1 9 6 8 ) 13) * Fedorchenko, V.J et#l (Lqgs) I~)
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i n f o r m a t i o n can be d e r i v e d from gas s o l u b i l i t y m e a s u r e m e n t s than just the knowledge of s o l u b i l i t y values. If the gas s o l u b i l i t y in m i x e d s o l v e n t s is s m a l l the solubility data give q u a n t i t a t i v e i n f o r m a tion about the t h e r m o d y n a m i c behavior of the c o m p o n e n t s of the m i x e d solvent. If these t h e r m o d y n a m i c data a r e known f r o m other independent m e a s u r e m e n t s , the t h e r m o d y n a m i c s of the m i x e d solvent d e r i v e d from gas solubility m e a s u r e m e n t s can be used to check the t h e r m o d y n a m i c c
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