MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF YTTRIA-STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS CONTAINING DISPERSED TIC PARTICLES

The microstructure and mechanical properties of hot-pressed yttria-sta bilized tetragonal zirconia polycrystals (Y-TZP) ceramics containing u p to 30 vol % TiC particles were studied. Adding TIC particles to Y-TZ P improved the bending strength and fracture toughness. With 20 vol % TiC particles the maximum bending strength and fracture toughness reac hed 1073 +/- 30.4 MPa and 14.56 +/- 0.25 MPa m(1/2), respectively. The residual tensile stress induced by the thermal expansion difference b etween ZrO2, and TiC must have inhibited the tetragonal-monoclinic tra nsformation. The stress-induced phase transformation was therefore not the dominant toughening mechanism. High-densities of dislocations wit hin TiC particles and microcracking were detected by TEM. The improved toughness of the materials is considered to be the result of crack de flection, crack bowing of TIC particles and microcracking toughening o f ZrO2.