Effect of bentonite addition on fabrication of reticulated porous SiC ceramics for liquid metal infiltration

SiC with different particles and a clay mineral bentonite (montmorillonite) were mixed in water to prepare ceramic slurry. The slurry was then infiltrated high porous polyurethane sponge. Excess slurry was squeezed out to adjust ceramic rate in the infiltrated body. The pore walls were coated with ceramic mix after the infiltrated body was dried. The polyurethane containing SiC particles and bentonite was fired in a box furnace to burn out the polyurethane from the body at 500 °C for 30 min. The remaining porous ceramic bodies were sintered at elevated temperatures to give strength. SiC particles with bentonite surface coating took polyurethane pore forms after firing the sponge. Bentonite was both used as binder for ceramic slurry at room temperatures and the sintering additives at elevated temperatures. Therefore, increasing bentonite addition gives higher strength to the resulting ceramic performs.