Oxidation behavior at 300–1000C of a (Mo,W)Si2-based composite containing boride

The oxidation behavior of a (Mo,W)Si2 composite with boride addition was examined at 300–1000C for24 h in dry O2. The oxidation kinetics was studied using a thermobalance, and the oxide scales wereanalyzed using a combination of electron microscopy (SEM/EDX, FIB, BIB) and XRD. Accelerated oxidationwas found to occur between 500C and 675C, with a peak mass gain at 625C. The rapid oxidation isattributed to the vaporization of molybdenum oxide that leaves a porous and poorly protective silicalayer behind. At higher temperature (700–1000C) a protective scale forms, consisting of a dense SiO2/B2O3 glass