Accelerated oxidation behavior of NbSi2 coating grown on Nb substrate at 600–900 °C

Abstract Isothermal oxidation of NbSi 2 coating formed on Nb substrate was investigated in air at 600–900 °C, which exhibited the complex and accelerated kinetics at intermediate temperatures and failed due to either the cracking of the NbSi 2 coating or the oxide layer formed. This complex oxidation behavior was governed by the balance between the stress generated by the forming of oxide phases and the subsequent stress relaxation processes. Pesting-induced accelerated oxidation at 700 °C was affected by extrinsic factors such as pre-existing defects in NbSi 2 coating. Accelerated oxidation originated from the oxide layer cracking at 750 °C was intrinsic to NbSi 2 .