Preparation and properties of mullite-bonded porous SiC ceramics using porous alumina as oxide

Mullite-bonded porous silicon carbide ceramics were prepared by an in situ reaction bonding technique and sintering in air with SiC, porous Al2O3, and graphite as starting materials. The pores in the ceramics were formed by burning graphite and by stacking particles of SiC and Al2O3. The surface of SiC was oxidized to SiO2 at high temperature. With a further increase in temperature, SiO2 reacted with Al2O3 to form mullite. The reaction-bonding characteristics, phase composition, open porosity, mechanical strength as well as the microstructure of porous SiC ceramics were investigated.