On the Mechanism of Formation of Thin Oxide Layers on Nickel

Abstract

It could be demonstrated that the initial period of oxidation of nickel at 400° and 500°C is governed by a logarithmic rate law. However, after approximately 5 hr at 400°C and 1 hr at 500°C the rate of oxidation changes into a fourth power rate law ruling in a special oxide‐thickness region. This rate law can be understood if a negative space charge, caused by nickel‐ion vacancies, in the growing layer is assumed and if the current of nickel‐ ion vacancies from the surface of the oxide layer to the metal‐oxide interface is caused predominantly by an electric field established over the layer. The experimental results of the oxidation of nickel are in fair agreement with the proposed mechanism.