A STUDY IN SHORT ALUMINA FIBER-REINFORCED MULLITE COMPOSITES

A study has been made of the fabrication and characterization of short alumina fibre-reinforced mullite ceramic matrix composites. The specimens were fabricated via a conventional ceramic process, i.e. pressureless sintering of mixed fibre and powder compacts. A reasonable sintered density (> 90% theoretical) was obtained, depending on the fibre loading and the uniformity of fibre dispersion. These conventionally sintered composites exhibit improved fracture toughness. As an example, an indentation toughness of approximately 13 MPam0.5 was measured for the composites containing > 20 vol% alumina fibres. The relationship between microstructure and mechanical properties in these short ceramic fibre-reinforced ceramic matrix composites is discussed, together with suggestions for further work.