Oxidation behaviour of nano-sized SiC particulate reinforced Alon composites

摘要

Silicon carbide (SiC)-aluminium oxynitride (Alon) ceramic composites exhibited improved mechanical properties, but the high temperature oxidation behaviour was unknown. The aim of this investigation was to identify oxidation characteristics and kinetics of 8 wt% SiC-Alon composites over a temperature range between 700 °C and 1200 °C in air. The Alon matrix and SiC particles near the surface were oxidized to form Al_2O_3 and SiO_2, respectively. The starting oxidation temperature of Alon was observed to be about 1000 °C. While the addition of nano-sized SiC particles resulted in a reduced starting oxidation temperature due to the large cumulative surface area and high total surface energy, the oxidation resistance at higher temperatures of 1100 °C and 1200 °C was remarkably enhanced. The oxidation kinetics changed from a linear weight gain for pure Alon into a logarithmic weight gain for the composites due to the formation of a dense protective oxidation layer arising from the presence of SiO_2.