On the Mechanism of MoSi2 Pesting in the Temperature Range 400–500°C

The oxidation of a MoSi2 composite was studied in the temperature range 400–500°C. The peak pesting temperature was identified and the oxidation kinetics was observed up to a holding time of 4000 hours. The reaction kinetics was tracked using thermogravimetric analysis :IS well iis oxide thickness nieasurenients. A detailed analysis of the morphology and composition of the oxide was performed using SEM and EDX. The peak pesting temperature was found to be 470°C. The reaction kinetics in static air could be described with two consecutive parabolic oxidation curves, one up to 500 hours and another between 500–4000 hours. With a higher water vapor coiitent the kinetics showed linear behwior. MoO3 evaporation took place during the entire duration of the oxidation. The oxide appeared to grow by inward diffusion of oxygen to the oxidehulk interface.