High-temperature oxidation of materials

Abstract

The high-temperature oxidation of a wide variety of materials has been investigated, viz: group I-VIII metals and their alloys; refractory compounds involving carbides, nitrides, borides, and silicides of the group IV-VI transition metals, and materials based on them; and composite materials for various applications. The basic laws and mechanisms of interaction of these materials with gaseous media have been determined. Heat resistance vs composition relationships for various types of binary systems have been defined, based on studies carried out over a broad range of temperatures (500–1600°C), concentrations of second component (0–100%), and an oxidation time of 10 hours. The redistribution of alloying elements during oxidation has been studied, and its effect on oxygen solubility, heat resistance, phase composition and morphology of the scale, and structure of the scale—alloy interface clarified. The definitive role of metal — ion diffusion in the oxidation behavior of titanium and zirconium, and the catastrophic oxidation of zirconium and its alloys, has been demonstrated. Alloying group IV metals with elements of higher valency produces a reduction in oxygen solubility due to the increase in electron concentration, and a reduction in the extent of scaling. The relationship of the heat resistance vs composition diagrams to the phase diagrams of the binary systems has been elucidated.