Oxide laminated composites with aluminum phosphate (AlPO₄) and alumina platelets as crack deflecting materials

Oxide-oxide laminated composites with aluminum phosphate (AlPO₄) and alumina platelets as crack deflecting interphases were developed by the tape casting method. Dense bodies of Al₂O₃, mullite, 50 vol% Al₂O₃·50 vol% YAG in situ composite, and 3Y-TZP were sintered and characterized. Tape casting formulations for different oxides with solid contents of 25.1 and 30 vol%, respectively, were developed. XRD indicated compatibility between alumina, mullite, zirconia and AlPO₄. Laminated, matrix-interphase composite systems consisting of Al₂O₃-AlPO₄, mullite-AlPO₄, 50 vol% Al₂O₃·50 vol% YAG in situ composite-AlPO₄, and 50 vol% Al₂O₃·50 vol% YAG in situ composite-alumina platelets were made. The 50 vol% Al₂O₃·50 vol% YAG in situ matrix-alumina platelet composite showed 'quasi-elastic' load-displacement behavior under the conditions of fabrication, and had a 3-point bending strength and work of fracture of 188±8 MPa and 0.65±0.02 kJ/m², respectively. The 3Y-TZP-AlPO₄ laminated composite could not be made because of delamination due to thermal expansion mismatch.