Processing, microstructure and mechanical strength of reaction-bonded Al2O3 ceramics

Reaction-bonded Al2O3 (RBAO) ceramics were fabricated from attrition-milled Al/Al2O3 powder mixtures. Two different Al precursor powders and several contents of Al were used. The raw materials and the RBAO powder mixtures were studied in terms of grain size, oxidation behaviour (TGA/DTA), morphology and microstructure. The influence of the important parameters controlling the RBAO process is first discussed. Secondly, the microstructure of RBAO bodies uniaxially pressed and heat-treated in air, up to 1100 and 1250 °C, is reported and their mechanical strength is evaluated and compared to conventional Al2O3 ceramics.