Fabrication and Characterization of Slip-Cast Layered Al2O3-ZrO2 Composites
Monolithic and three-layered Al2O3-15 vol. % ZrO2 composites were fabricated by slip casting aqueous slurries. The outer and inner layers of three-layer composites contained unstabilized and partially stabilized ZrO2, respectively. Transformation of part of the unstabilized ZrO2 led to surface compressive stresses in the outer layers. Strain gage, xray, indentation crack length, and strength measurements were used to determine the magnitude of residual stresses in the composites. The strength of the three-layer composites (1.1 to 1.2 GPa) was 500–700 MPa higher than that of the monolithic outer layer composites at room temperature and 350 MPa higher at 750°C. The strength differential decreased rapidly above the monoclinic to tetragonal transformation temperature. Three-layered composites showed higher Weibull modulus and excellent damage resistance. Cam follower rollers were fabricated to demonstrate the applicability of this technique for making automotive components.
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