Abstract
For the homogeneous dispersion of ZrO2 particles in Al2O3/ZrO2 ceramics, Zr-precursors were mixed with oxide Al2O3 powders by chemical routes such as partial precipitation or partial polymerization of Zr-nitrate solutions.When the Zr-Y-hydroxide were coprecipitated among the ultrafine Al2O3 oxide powders followed by calcination, homogeneous dispersion of nano-sized ZrO2 particles in Al2O3/ZrO2 composite ceramics could be obtained. But because of the coalescence of dispersed ZrO2 particles, dispersed ZrO2 was grown up to more than 200nm when sintered at the temperature of higher than 1500C. But when the sintering temperature was kept to lower than 1400C by using nano-sized alumina, the particle size of dispersed ZrO2 could be sustained below 100nm. But the coalescence of dispersed ZrO2 between Al2O3 particles could not be avoided so that the mechanical properties were not enhanced much as expected.In the contrary, when Zr-polyester precursors were precipitated and coated to the surface of ultrafine alumina powders by the polymerization of Ethylene Glycol with Citric Acid and Zirconium Nitrate, much more uniform dispersion of ZrO2 was achieved at 1450~1600C of sintering temperature ranges. And due to especially discrete dispersion of ZrO2 particles between Al2O3, their mechanical strength was more enhanced than mechanical mixing or hydroxide precipitation methods.
