Silicon oxycarbide ceramic foams from a preceramic polymer

Open-cell ceramic foams were obtained from the pyrolysis, at 1000 degrees to 1200 degrees C under nitrogen, of a preceramic polymer (a silicone resin) and blown polyurethanes. The morphology of the expanded polyurethane was reproduced in the final architecture of the ceramic foam. The foams produced in this way consisted of an amorphous silicon oxycarbide ceramic (SiOC), having a bulk density ranging from 0.1 to 0.4 g/cm(3) and variable cell size (300 to 600 mu m). Young's modulus ranged from 20 to 170 MPa, and the compression strength from 1 to 5 MPa. The foams displayed excellent dimensional stability up to their pyrolysis temperature.