Tetragonal Zirconia Polycrystals Reinforced with SiC Whiskers

Abstract

The microstructure and the mechanical properties of hot‐pressed tetragonal ZrO 2 polycrystals (TZP) reinforced with up to 30 vol% SiC whiskers were studied. The SiC whisker‐TZP composites were stable under the hot‐pressing conditions at 1450°C. Annealing in an oxidizing atmosphere at ∼1000°C resulted in glass formation and microcracking caused by whisker oxidation and transformation of the ZrO 2 grains near the whiskers to monoclinic symmetry. The fracture toughness was markedly improved by the dispersed whiskers (∼12 Mpa·m 1/2 at 30 vol% SiC) compared to the values measured for the matrix (∼6 Mpa·m 1/2 ). The flexural strength of the hot‐pressed TZP‐30 vol% SiC whisker composite at 1000°C (∼400 MPa) was twice that of the TZP matrix.