Roughness and oxidation: application to NiO growth on Ni at 800°C

The changes with oxidation time of the oxide outer surface roughness, the oxide grain size and the oxidation rate constant kc for NiO growth on Ni were studied at 800°C in 1 atm oxygen. The roughness was determined by optical interferometry establishing 2D-profiles and 3D-images. Correlations were found between the variations of the oxide outer surface roughness or the kc values and the oxide grain size. These are attributed to the decrease of the oxide grain boundary density with time, which induces a decrease of the effective diffusion coefficient.