On the oxidation behaviour of MoSi2

The oxidation behaviour of MoSi2 has been analyzed on the basis of thermodynamics and kinetics. Thermodynamically speaking silica is in equilibrium with any of the stable molybdenum silicides. At low temperatures, the limited bulk diffusion in MoSi2 makes it impossible to sustain a sufficient supply of silicon for the formation of a continuous silica layer. This leads to the simultaneous-oxidation of silicon and molybdenum, forming a scale of mixed oxides. The formation of molybdenum oxides leads to ruptures owing to the significant volume change and accelerates the oxidation, leading to the pest phenomenon.