High-temperature behavior of Al-doped polymer-derived SiAlOC glasses in air environment

Aluminum-containing silicon oxycarbide (SiAlOC) glasses have been obtained through pyrolysis in argon atmosphere at 1000 °C of a polymethyl(phenyl)siloxane resin and aluminum tri-sec-butoxide-derived siloxane networks. To investigate their high-temperature behaviors in air environment, these glasses were further annealed at 1000, 1200, 1400, 1600, and 1700 °C. It was found that the redistribution reactions between Si-O and Si-C bonds initiated at 1000 °C and almost finished at 1200 °C; oxidation of the SiAlOC glasses occurred at temperature above 1000 °C; and the crystallization of mullite took place at 1400 °C due to the inclusion of Al ion into the silica network to form Si-O-Al linkages.