The Influence of Erosion-Induced Roughness on the Oxidation Kinetics of Ni and Ni-20Cr Alloys

Surface roughness plays a dominant role inincreasing the oxidation rate of metals and alloysduring erosion compared to the oxidation rate in staticair. Ni and Ni-20Cr were eroded at two different impact velocities (35 and 65 m/s) and for twodifferent impact angles (90° and 30°). Theeroded samples were subsequently isothermally oxidizedin static air at three different test temperatures. Theincreased oxidation kinetics in the case of Ni could beexplained on the basis of increased roughness caused byerosion prior to oxidation. In the case of Ni-20Cr, theeffect of increased roughness on oxidation was largely offset by the fact that the number ofgrain-boundary diffusion paths decreased due tocoarsening of the grains of the oxide scale.