Processing of closed-cell silicon oxycarbide foams from a preceramic polymer

A novel processing route for fabricating closed-cell ceramic foams has been developed. The strategy for making the ceramic foams involves: (i) forming some shapes using a mixture of preceramic polymer and expandable microspheres by a conventional ceramic forming method, (ii) foaming the compact by heating, (iii) cross-linking the foamed body, and (iv) transforming the foamed body into ceramic foams by pyrolysis. By controlling the microsphere content and the pyrolysis temperature, it was possible to adjust the porosity ranging from 56 to 85%.