In-situ reaction bonding of porous SiC ceramics

Porous SiC ceramics were prepared by an in-situ reaction bonding process from SiC, Al2O3 and graphite in air at 1400–1550 °C. The reaction bonding behavior during the sintering was studied. The surface of SiC particles is oxidized to amorphous silica above 750 °C. When the sintering temperature reaches 1100 °C, the amorphous silica begins to be crystallized to cristobalite. After 1400 °C, the oxidation-derived silica reacts with Al2O3 to form mullite. Porous SiC ceramics are bonded by the silica and mullite. In addition, the effects of sintering temperatures on the reaction bonding behavior, open porosity and flexural strength were investigated.