EFFECTS OF PROCESSING ON MECHANICAL-PROPERTIES AND MICROSTRUCTURE OF A CERAMIC COMPOSITE

The effects of processing on the microstructure and mechanical behaviour of a Tyranno SiC fibre-reinforced zirconia titanate composite were evaluated. The microstructure was analysed using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Mechanical behaviour was characterized by strength and toughness measurements, which were correlated with the microstructure of the composite and its fibre/matrix interface. BN-coated fibres modified the interfacial microstructure by allowing debonding and fibre pull-out to occur. Incorporating CO-treated fibres and hot-pressing in an atmosphere of CO at an overpressure of 111.5 kPa limited fibre degradation during consolidation and resulted in improved in situ fibre strength. As a result, a strong (705 MPa) and tough (17.1 MPa m(1/2)) Tyranno SiC fibre-reinforced composite was fabricated via hot-pressing at 1270 degrees C at an applied pressure of 17.25 MPa.