Delaminated zeolite-catalysed synthesis of high-molecular weight polycarbosilane as a low shrinkage SiC precursor

Abstract

A polycarbosilane (PCS) with a higher number-average molecular weight (2710 vs. 1570), and hence with a higher ceramic yield (74 vs. 68%), compared to a commercial Nipusi type S PCS has been synthesized via the catalytic decomposition of polydimethylsilane at 400 degrees C using H-ITQ-2, a delaminated zeolite with a very high external surface area, as a solid acid. The silicon carbide film fabricated using this PCS was found to show a much lower level (16 vs. 39%) of shrinkage than the commercial PCS-derived film, together with better mechanical properties, suggesting the potential of its preceramic polymer to produce robust ceramic coatings. (c) 2007 Wiley Periodicals, Inc.