Oxygen Sinks in SiC-Based Ceramics

Abstract

AbstractDuring an HREM/AEM investigation, two different oxygen sinks were identified for a variety of SiC-ceramics involving different sintering mechanisms: segregation of oxygen to i) internal interfaces, and ii) “excess-carbon” secondary phases consisting of basically turbostratic graphite and an intermediate amorphous Si-C-O phase. Si-C-O glasses and polycarbosilanebased nonstoichiometric SiC materials (Nicalon fibers) are well suited as model systems to evaluate the structure and the stability range of the amorphous Si-C-O phase in SiC-based ceramics.