ZrO2 fiber-matrix interfaces in alumina fiber-reinforced model composites

Properties of the fiber/matrix interface in monoclinic ZrO2-coated alumina fiber-reinforced composites were investigated using model composites with dense alumina matrix and single alumina fibers. The fiber-matrix porous interface was produced via dip-coating single fibers in monoclinic ZrO2 suspensions and two different particle sizes were used in order to vary the coating porosity. The interfacial sliding stress was determined via fiber pushin test; crack deflection behavior was analyzed from cracks created via Vickers indentation and via fracture surface. Fracture toughness and elastic modulus of interface, matrix and fibers were evaluated and used to predict the crack deflection behavior using the model of He and Hutchinson. Results showed that monoclinic zirconia interfaces are suitable for dense alumina composites, due to the low fiber/interface chemical interaction. A uniform coating can be produced via dip coating and tailored with using different monoclinic zirconia particle sizes. The sliding stress values obtained with the pushin test were about 120 MPa.