Effect of PVB on Microstructure and Properties of SiC Ceramics with Gradient Pore Channel Structure

SiC ceramics with gradient pore channel structure were fabricated by directional freeze-casting and low temperature vacuum drying method. A slurry was selected, which consisted of tert-butyl alcohol(TBA), polyvinyl butyral(PVB), SiC powders and sintering additives. Effect of PVB content on porosity, microstructure and mechanical properties of the SiC ceramics with gradient pore channel structure was studied. The results show that pore size gradually decreased and compressive strength of the SiC ceramics increased with the increase of PVB content, but open porosity had little change. The SiC ceramics containing 3vol% PVB sintered at 1 400 ℃ had an axial compressive strength of 87.5 MPa and a porosity of 62.4%.