SiAlON-based ceramics from filled preceramic polymers

Commercial polysiloxanes filled with alumina nanoparticles and AIN and Si ₃N ₄ micropowders have been used for the preparation of β-SiAlON in nitrogen, at 1450°-1550°C. SiAlON was preceded by intermediate alumino-silicate phases like mullite and sillimanite. Although reduction and nitridation to β-SiAlON finally occurred, the SiAlON yield at high temperatures was lowered by corundum contaminations. The yield was also possibly affected by phase separation in the SiOC glass residue derived from silicones. A composition refinement reduced contamination and provided a promising route for SiAlON from filled preceramic polymers.