Isothermal oxidation behaviour of a polymer-derived amorphous SI/C/N ceramic
Abstract
Polymer-derived non-oxide ceramics are candidate materials for various applications especially in the high-temperature regime above 1200°C, where conventionally liquid-phase sintered ceramics start to fail due to softening of their glassy grain boundary phase. The polymer-to-ceramic approach uses high-purity educts from polymer chemistry. It allows for an additive-free synthesis of ceramic materials and thus avoids the presence of glassy grain boundary phases in the body. In this work, the oxidation behaviour of poly(hydridomethyl)silazane NCP200-derived ceramic materials is investigated in more detail. Therefore, after standardised crosslinking and ceramisation the amorphous ceramic material was milled and sieved to a powder fraction with r ? 32µm. These powders with high surface-to-volume ratio were isothermally oxidised for 20 h using a TGA at temperatures between 1000°C and 1500°C in steps of 100K, each a sample of approx. 120mg in an alumina crucible. Preliminary results on the oxidation behaviour of the specimens are reported and the mechanisms of oxidation are outlined.
