Preparation of porous SiC ceramics by an infiltration technique

:The possibility of infiltration as a technique for synthesizing porous SiC ceramics was examined. SiC powder compacts were infiltrated with a liquid precursor which produced SiO2 during pyrolysis in air at a low temperature. Infiltrated SiO2 might act as a bond between the neighboring SiC particles at contacting points. The process parameters which control the rate of infiltration of liquid precursor to SiO2 into porous SiC powder compacts were studied. Results showed that the infiltration rate could be estimated by using weight gain measurements. Sintering infiltrated bodies at 1300 °C yielded specimens in which only silicon carbide and cristobalite were detected. The presence of cristobalite significantly controlled the porosity as also the mechanical properties. Reasonable flexural strengths (∼ 48 MPa) could be achieved at a porosity level of 26 vol.% with near uniform pore diameter of around 5 μm.