Oxidation behavior and mechanism of oxidation of Si3N4/TiC micro-nanocomposite ceramic materials

摘要

Oxidation behavior of hot-pressed Si3N4/TiC micro-nanocomposite ceramic materials with Al2O3 and Y2O3 as sintering additives was investigated at a dry air temperature of 800-1250 degrees C. The experimental study included analyses of oxidation behavior and mechanism. The results show that the relationship between oxidation mass gain and oxidation time is parabolic, where gains in the oxidation mass increase with the growth of TiC content. The surface layer composition of materials after oxidation was investigated with X-ray diffraction. The oxide layer is composed mainly of SiO2 and TiO2, and a small amount of Si3N4 or TiC phase can be found on the oxidation surface layer, thereby implying that the surface layer is significantly covered with oxides after oxidation at 1250 degrees C for 100 hrs. Scanning electron microscopy (SEM) reveals that the oxidation behavior results in a large number of microcracks and holes in the oxide layer.