THERMAL-BEHAVIOR OF POLYMER-DERIVED CERAMICS .1. SI-C AND SI-C-O SYSTEMS FROM BOTH COMMERCIAL AND NEW POLYCARBOSILANE (PCS) PRECURSORS

Si-C- and Si-C-O-based ceramics from new or commercial polymeric precu rsors are compared. The emphasis is upon the structural and textural f eatures as observed by high-resolution transmission electron microscop y (HRTEM), and their evolution with an increasing heat-treatment tempe rature up to 1800-degrees-C. Specifically, the behavior of an increasi ng excess of carbon-with regard to the Si-C stoichiometry-is revealed, and the consequences on the nucleation and the growth of the SiC grai ns and the electrical properties are discussed.