Microstructure and Oxidation of (La,Sr)CrO3-Added Ti3SiC2 Composites

Composites of Ti3SiC2-(10, 20, 40)wt% La0.8Sr0.2CrO3 were synthesized by hot pressing powders of Ti3SiC2 and La0.8Sr0.2CrO3. These powders reacted to form stable TiC carbides and LaTiO3, Cr2Ti4O11, La2O3, and SrCrO4 oxides during hot pressing. The composites consisted primarily of a fine TiC-rich matrix phase and coarse Ti3SiC2 dispersoids. The addition of oxidation-immune La0.8Sr0.2CrO3 into Ti3SiC2 increased the oxidation rate because TiC formed during hot pressing. During oxidation of the composites at 800-1000 degrees C for 100 h in air, Ti diffused outward to form an outer rutile-TiO2 layer, and oxygen transported inward to form an inner oxide layer.