Oxidation of Ti₃SiC₂ composites in air

The oxidation of Ti3SiC2 Composites (75 at. pct Ti3SiC2 and 25 at. pct TiCx), prepared via self-propagating high-temperature synthesis (SHS) and subsequent shock consolidation, has been studied in the range of 1073 to 1573 K in this research. The oxidation kinetics are parabolic with an activation energy of approximately 240 +/- 20 kJ/mol. As shown by transmission electron microscopy (TEM) during the very early stages of oxidation, the oxide layer formed contains amorphous SiO2 and crystalline rutile (TiO2). As oxidation proceeds, a two-layered oxide scale is observed with the outer oxide layer consisting of columnar TiO2 with trace amounts Of SiO2 and the inner oxide layer being comprised of a mixture of amorphous SiO2 and fine crystalline TiO2. The grain size of the outermost oxide (TiO2) increases with increasing oxidation temperature. The oxidation resistance of the Ti3SiC2 composites prepared by SHS and subsequent shock consolidation is similar to the oxidation of Ti3SiC2 prepared by other means with comparable parabolic constants.