Preparation and characterization of nano-sized Al₂O₃/ZrO₂ powders

Synthesis of high performance composite powders is the key to prepare nanocomposite ceramics. The final powders of Al₂O₃/ZrO₂ with excellent chemical homogeneity were synthesized by heating of ethanol-aqueous salt solutions combined co-precipitation method. The effect of the precipitant on the agglomeration was researched. The powders are identified by transmission electron microscopy (TEM), X-ray diffraction (XRD), BET, TG and differential thermal analysis (DTA). The results demonstrate that the using of ammonium hydrogen carbonate produced a basic carbonate precursor that was loosely agglomerated and the resultant powders showed good dispersivity and excellent sinterability. The formation temperature of tetragonal zirconia crystals increases, while the conversion temperature of α-Al₂O₃ phase decreases sharply. The powders convert to t-ZrO₂ phase and α-Al₂O₃ phase completely at 1100°C. The powders have good dispersion, uniform grain size and no hard agglomeration. Nanoscaled Al₂O₃/ZrO₂ powders with particle size of 15-20 nm and specific surface area of 69.5 m²·g^-1 can be obtained.