Kinetics and Mechanism of Nickel-Sulfur Reaction

Abstract

Kinetics and mechanism of the reaction between nickel and sulfur vapors were investigated in the temperature range 480°–640°C under atmospheric pressure. The sulfurization of nickel has been found to follow, under these conditions, the parabolic rate law. The activation energy of this process amounts to 22 kcal/mole. The examination of x‐ray patterns of the scale formed on the surface of the metal has demonstrated that this scale layer is composed almost entirely of . Morphologic investigations show that the scale is composed of two distinct layers. The outer layer, constituting the main part of the whole scale, is compact, polycrystalline, and exhibits an ordered growth texture. The inner layer is porous and does not exhibit any growth texture. The investigations carried out with the aid of the radioactive sulfur isotope 35S have demonstrated that the sulfide scale on nickel is formed exclusively by the outward diffusion of the metal.