The action of borates as inhibitors for the high temperature oxidation of alloys

Abstract

The oxidation of metals and alloys at high temperature is usually considered to be a diffusion limited process, controlled ultimately by the concentration of defective lattice sites in the growing oxide film. Measures for controlling rates of oxidation usually depend, therefore, on replacing the oxide phase normally formed by another with a more favourable structure, or by doping the oxide to reduce the concentration of defects. These measures require the presence of a modifying agent either as a constituent of the alloy or as a relatively thick surface coating, and very few cases are known in which useful effects have been obtained by applying traces of material to the surface. There has therefore been no effective development of inhibitors for high temperature oxidation analogous to the well known inhibitors of wet corrosion, suitable for application ex post facto .