PROCESSING OF MICROCELLULAR SIC FOAMS .2. CERAMIC FOAM PRODUCTION

A replication process for producing fine open-celled ceramic foam from preceramic polymers is presented and analysed. In this process, a porous sodium chloride compact formed by sintering was first infiltrated with polycarbosilane. After dissolution of the salt, the resulting polymer foam was cured by oxidation in air and pyrolysed to form a silicon carbide foam. The curing stage is the most critical step, and was investigated using a series of controlled curing experiments and finite-difference modelling of heat transfer during curing. Good agreement has been found between theory and experiment. The model was then used to investigate the limits of the process and to provide stategies for successful curing of the foams without melting or cracking.