| Abstrakt: |
ZrO2powder has been coated with SiO2using an alkoxide sol. The isoelectric point of the coated powder changes to 2.5, a value which is characteristics of SiO2. The ZrO2powders coated with different amounts of SiO2are mixed with Al2O3powder in an aqueous suspension. The mixed powders, containing 10 vol% coated ZrO2are dried, compacted and sintered to prepare ZrO2toughened Al2O3(ZTA) composites. The composites possess very high densities (∼ 98%) and, at a SiO2content of 1 mol% of ZrO2, the Klcis ∼ 5.8 MNm−3/2. The Weibull modulus of the composites improves by a factor of 2. A large improvement in the surface smoothness of the as-sintered samples, prepared using the coated powders, as compared to the ZTA prepared using the uncoated powders, is obtained. These results point to a blunting of the surface flaws in the composites prepared using the coated powders. |
