Oxidation kinetics of a Ni-Cu based cermet at high temperature

The oxidation kinetics of a cermet composed of Ni-Cu alloy and nickel ferrite was studied by thermogravimetry at 960 degrees C under oxygen in the range 0.5-77 kPa. After an initial mass increase up to 15 g/m(2) due to oxidation of surface metallic particles, the mass change was attributed to both outwards NiO growth and internal oxidation. Above 40 g/m(2), the NiO scale thickness remained constant and the oxidation kinetics followed a complete parabolic law. The variations of the kinetic rate with oxygen partial pressure allowed to propose mechanisms, rate-controlling steps and kinetic laws in both transient and long term oxidation periods. (C) 2012 Elsevier Ltd. All rights reserved.