Fabrication, Structure and Properties of Porous SiC Ceramics with High Porosity and High Strength

摘要

Porous SiC ceramics with high porosity and high strength were fabricated by gelcasting,with tert-butyl alcohol (TBA) as solvent,acrylamide (AM) as monomer,and in-situ reaction bonding with α-Al2O3 as sintering additive.SiC suspension with 10 vol％ solid loading was successfully solidified by gel-casting to form high strength green body.The results showed that the compressive strength of the porous SiC ceramics increased with sintering temperature from 1300 to 1450 °C,but porosity had little change,due to formation of more volume of cristobalite and mullite phases on the surface of SiC grains,accompanied by a large volume expansion effect.Very narrow single-peak distributions with about 2 μm median pore diameter could be found for the porous SiC ceramics.The porosity and compressive strength of the porous SiC ceramics sintered at 1450 °C were 71.21％ and 12.14 MPa,respectively.