Oxidation behaviour and high temperature strength of alumina-silicon carbide nanocomposites

The processing of Al₂O₃-SiC nanocomposites has been examined in detail. It has been found that processing in water as opposed to organic solvents leads to a more reproducible nanocomposite. High strengths at room temperature have been obtained with the addition of only 5 vol% nanometric SiC in nanometric α-Al₂O₃, densified by hot pressing. In the current study, the high temperature strength of alumina-silicon carbide nanocomposite materials prepared in this way has been measured at 1150, 1250 and 1350°C. Oxidation in air and corrosion experiments in a flue gas composed of 80.8% N₂, 15% CO₂, 4% O₂ and 0.2% S₂, were also conducted at these temperatures. Al₂O₃-5 vol% SiC nanocomposite maintained strengths of greater than 550MPa at temperatures up to 1250°C. The gain in mass per unit area during oxidation in air was very low, even after 96 hours at 1350°C.