Oxidation behavior of silicon carbide based biomorphic ceramics prepared by chemical vapor infiltration and reaction technique

The oxidation behavior of biomorphic SiC based ceramics with different microstructure and composition was studied at 1450 °C in airflow for 50 h by thermal gravimetric analysis (TGA). SiC with amorphous, coarse grain, crystalline and fine grain crystalline microstructures as well as SiC–Si₃N₄ composite ceramics were processed from paper preforms by chemical vapor infiltration and reaction technique. The ceramics were characterized by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDX) before and after oxidation. The results show that the crystalline SiC with fine grain structure and SiC–Si₃N₄ composite ceramics show very good oxidation resistance at a temperature of 1450 °C.