The Thermodynamics of the Ni-Co-S Ternary System

The thermodynamic properties of the Ni-Co-S ternary system were determined by equilibrating the system with a known sulfur pressure established by using a gas mixture of H2S/H2 at 1373, 1473, and 1573 K. The isoactivity contours for Ni and Co were determined by application of the Gibbs-Duhem equation using Schuhmannʹs method for ternary systems. For this purpose, a computer program was developed to calculate the activities of nickel and cobalt. The cobalt activity coefficients in dilute solutions of cobalt in the nickel-cobalt-sulfur system were evaluated and found to be 0.33, 0.50, and 0.55 at 1373, 1473, and 1573 K, respectively.