High-temperature evolution behavior of MK silicon resin derived SiOC ceramics under different environments

Silicon oxycarbide (SiOC) ceramics has been prepared by polymethylsilsesquioxane (MK silicon resin) under inert environment at 1000 °C in the present work. The evolution behavior of compositions and structures of MK silicon resin derived SiOC ceramics at high temperatures in different environments were studied systematically. It was found that in inert environment, the rearrangement of Si–C and Si–O bonds took place at 1200 °C–1500 °C and the carobothermal reductions of SiOC ceramics were activated at 1500 °C. While in reduced pressure environment, lower pressure reduced the activation temperature of carbothermal reductions to 1400 °C. In air environment, partial Si[(O,C)4] network oxidation and free carbon oxidation occurred at high temperatures, which would generate a large amount of SiO2 and played a protective role in the interior of SiOC ceramics.