Deoxidation Equilibrium of Silicon in Liquid Nickel and Nickel-Iron Alloys.

Abstract

The deoxidation of liquid nickel with silicon has been determined at temperatures between 1500 and 1650°C using quartz crucibles in order to investigate the deoxidation of nickel based alloys. The effect of temperature on the equilibrium constant of the deoxidation reaction:SiO2(s)=Si+2Owas found to be:log KSi(Ni)= – 15680 / T + 1.83 while the deoxidation product, log K'Si(Ni) ( = [%Si][%O]2), up to 2 mass% of silicon was expressed as follows:log K'Si(Ni)=log KSi(Ni) – 0.06[%Si]The deoxidation of nickel–iron binary with 0.5 mass% silicon has been measured over all the ranges of the binary system including pure iron at temperature of 1600 and 1650°C. On the nickel basis, the deoxidation product of nickel–iron alloys, which increased by the addition of iron up to 20 mass%, was empirically represented to be:log K'Si(Ni–Fe) = log KSi(Ni)–(288 / T–0.197)[%Fe]The temperature dependence of the equilibrium constants for the deoxidation of iron was given by the expression:log KSi(Fe) = – 30960/T+11.86at temperatures between 1550 and 1650°C. On the iron basis, the value of log K'Si(Fe–Ni)' which decreased with the increase of nickel content up to 60 mass%, was calculated as:log K'Si(Fe–Ni) = log KSi(Fe) – 0.01[%Ni].