Effect of forming methods on porosity and compressive strength of polysiloxane-derived porous silicon carbide ceramics

Abstract

Open-cell silicon carbide foams were fabricated from a blend of carbon-filled polysiloxane using three different plastic forming methods: compression molding, injection molding, and extrusion. Compression molding process led to more homogeneous microstructure than the other forming methods, resulting in superior compressive strength (20.6 MPa at 72.4% porosity). In contrast, extrusion molding led to higher porosity (∼84%) than the other forming methods (72–74%) as a result of a higher level of expansion of expandable microspheres. Injection molding process led to a partial segregation of expanded microspheres and resulted in moderate compressive strength (9.1 MPa at 74.1% porosity).