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.