High‐Temperature Oxidation of a Cu–Ni Based Cermet: Kinetic and Microstructural Study

Abstract

The oxidation of a cermet composed of nickel ferrite (Ni x Fe 3− x O 4 ), nickel oxide (Ni y Fe 1− y O), and Ni–Cu alloy (Cu z Ni 1− z ) (with x =0.8, y =0.84, and z =0.44) has been studied by thermogravimetry, at 960°C, under controlled oxygen partial pressure. The rate of oxidation increases with the oxygen partial pressure up to 5.1 × 10 3 Pa, then it becomes independent of the oxygen pressure. This is due to the presence of the two copper oxides, CuO and Cu 2 O, above this oxygen pressure. Scanning electron microscopy observation of oxidized samples has shown that the oxidation mechanism involves both external and internal oxidation.