ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Thermodynamics of Zirconium Deoxidation Equilibrium in Liquid Iron by EMF Measurements
Ryo InoueTatsuro AriyamaHideaki Suito
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2008 Volume 48 Issue 9 Pages 1175-1181


Thermodynamics of Zr deoxidation equilibrium in liquid iron has been studied at 1873 K by using ZrO2–9mol%MgO and mullite (3Al2O3·2SiO2) electrolytes coupled with the quantitative alalysis of soluble Zr and insoluble Zr as ZrO2 by using a potentiostatic electronic extraction method. The soluble O content for a given soluble Zr content is lower than the previously reported values in the plot of soluble O vs. soluble Zr contents, and the oxygen activity for a given soluble Zr content is higher than the previously reported values. The free energy change of solid Zr dissolution into iron melt: Zr(s)=Zr at 1873 K is obtained as ΔG°=−153±10 kJ. The interaction coefficients for eOZr, rOZr and rOZr,O are estimated as −70±15, 901±131 and 10300±1500, respectively. However, the following interaction coefficients are represented by using a continuous function of logarithms of X, where X=[%sol.Zr]+5.7[%sol.O]+17.1[%sol.Zr]·[%sol.O]/(2[%sol.Zr]+5.7[%sol.O]):
eOZr=−3.70−2.20 ln X−2.07(ln X)2+(ln X)3
rOZr=dY/dX={−0.33+1.87 ln X+3.01(ln X)2}/X
OZr,O<11.4rOZr={−3.72+21.4 ln X+34.3(ln X)2}/X

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© 2008 by The Iron and Steel Institute of Japan
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