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.