Oxidation of Ti3SiC2 between 900 and 1200 degrees C in air

Abstract

Ti3SiC2 materials were synthesized by hot pressing using a new starting-material system consisting of a TiCx(x=0.6)/Si powder mixture. The oxidation of Ti3SiC2 at temperatures between 900 and 1200 degrees C in air for up to 100 h resulted in the formation of an outer TiO2 layer, an intermediate SiO2-rich layer and an inner (TiO2 + SiO2) mixed layer. During oxidation, Ti diffused outwards to form the outer TiO2 layer, and oxygen transported inwards to form the inner (TiO2 + SiO2) mixed layer. At the same time, the carbon in Ti3SiC2 escaped into the air. Below the scale, there was a narrow oxygen-affected zone, The oxidation at the scale-matrix interface proceeded by the disintegration of the lamellar Ti3SiC2 grains to form crystallites with a size of a few tens of nanometers containing oxygen. The detailed scale characteristics and oxidation mechanism are described.