Macro- and micro-cellular porous ceramics from preceramic polymers

Macrocellular and microcellular SiOC open cell ceramic foams were fabricated from a preceramic polymer. Macrocellular foams, with a cell size ranging from about 100–600 (mu)m and a bulk density ranging from about 0.25–0.58 g/cm^3, depending on the processing parameters, were fabricated using a direct foaming approach. Microcellular foams, with a cell size of about 8 (mu)m, were fabricated using poly(methyl methacrylate)microbeads as sacrificial templates. The bulk density ranged from about 0.31–0.48 g/cm^3, depending on the amount of microbeads in the starting material. The compression strength of the foams increased with increasing relative density, and microcellular foams possessed a 2–5 times higher crushing strength than macrocellular foams of similar density.