Silicon carbide-titanium carbide composite foams produced using a polymeric precursor

A polysilane solution used as a silicon carbide (SiC) precursor was mixed with different amounts of titanium carbide (TIC) powder and open cell polyurethane (PU) foams were dipped in these suspensions. The resulting pre-foams were pyrolyzed at 900 degreesC in nitrogen and then heated further at various temperature between 1100 and 1600 degreesC in the same atmosphere to produce SiC-TiC composite foams. The evolution of the composite foams has been studied using thermogravimetry and X-ray diffraction. The PU foam, pre-foams and the SiC-TiC composite foams were characterized by optical and scanning electron microscopy. These studies show that the pre-foams retained their shape well during pyrolysis and the composite foams produced consist of an open cell structure and hole-free solid struts. Prevention of cracking in the foams were dependent on the TiC content. The shrinkage observed during the conversion of the pre-foams to the composite ceramic foams can be controlled by varying the TiC content and the sintering temperature. (C) 2001 Elsevier Science Ltd. All rights reserved.