High-temperature evolution behavior of polymer-derived SiAlOC ceramics under inert atmosphere

SiAlOC ceramics were fabricated by pyrolysis of Al-doped polymethyl(phenyl)siloxane at 1000 °C. Then SiAlOC ceramics were annealed under inert atmosphere at 1200 °C, 1400 °C, 1500 °C and 1600 °C, respectively, to investigate their high-temperature evolution behaviors. The transformations of microstructural units resulting from bonds redistribution are observed from 1000 °C to 1400 °C. Creation of mullite at 1400 °C and its crystallization at higher temperatures are confirmed. Carbothermal reaction is effectively suppressed due to low content of free carbon and formation of mullite in SiAlOC ceramics. Accordingly, enhanced thermal stability of SiOC ceramics is realized by incorporation of Al element.