Fabrication and optimization of boron carbide foams by polymeric sponge replication

This study optimized the pore size distribution of boron carbide (B₄C) ceramic foam, which is manufactured by using the replica method by way of a polyurethane sponge template. Boron carbide particles and clay mineral bentonite powders were mixed in distilled water to prepare ceramic slurry. The slurry was then used to infiltrate polyurethane sponge that had an average pore size of 100 μm. The pore walls of the polyurethane sponge were coated with ceramic slurry after the sponge containing boron carbide particles and bentonite powder was fired in a box furnace at 500°C for 30 min to evacuate the polyurethane material and water from the body. The remaining structure was sintered at elevated temperatures to reach optimum pore distribution. The flow behavior of the ceramic slurry with different solid concentrations was evaluated with viscosity measurements, and a solid content of 55 wt% was obtained as the optimal ratio. Based on the results, the addition of 7·5% bentonite and a sintering temperature of 700°C are suitable for boron carbide foam. These rates have optimum values and are confirmed to be adequate for homogenous pore distribution of the foam.