High temperature isothermal oxidation behavior of NbSi2 coating at 1000-1450 °C

Isothermal oxidation behavior of NbSi2 coating grown on Nb substrate was investigated in air at 1000-1450 °C. Oxidation rate of NbSi2 coating increased with temperature at 1000-1300 °C but opposite trend was observed at 1300-1450 °C. Maximum oxidation rate was obtained at 1300 °C due to the highest porosity of oxide scale. Lowest oxidation rate was observed at 1450 °C due to formation of dense oxide scale by combined effect of volatilization of Nb oxide phase, viscous flow and densification of c-SiO2. Oxidation resistance of NbSi2 coating at these temperatures was governed by some inter-related factors.