MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF YTTRIA-STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS (Y-TZP) CONTAINING DISPERSED SILICON-CARBIDE PARTICLES

The microstructure and mechanical properties of pressureless sintered and subsequently hot isostatic pressed Y-TZP ceramics containing up to 20 vol% of SiC particles were studied. The grain growth of the ZrO2 matrix was not significantly affected by SiC additions. It was found that the hardness, Young's modulus and fracture toughness K(IC) increased, and the bending strength, sigma(b), decreased with increasing SiC content. The maximum K(IC) and sigma(b) were 7-8 MPa square-root m and 849 MPa, respectively. Silicon carbide additions caused increased flaw sizes, and reduced thermal stability of tetragonal zirconia during low-temperature ageing. The dominant toughening mechanism was microcracking. Stress-induced phase transformation played only a secondary role.