Preparation and microstructural evolution of cellular submicrocrystal Al₂O₃/TZP powders

Cellular submicrocrystal Al₂O₃/TZP powders (CSP) were successfully prepared by Al-Al(NO₃)₃ combustion synthesis assisted rapid atomization and water cooling (CS-RAWC). CSP mainly contains intracellular metastable Al₂O₃ phase with the grain size of ∼ 250 nm and intercellular t-ZrO₂ supersaturated solid solution (SS) phase with the thickness of ∼ 30 nm. The t-ZrO₂(SS) phases are t-Zr_1-x-yAl_xCe_yO_2-x/2 and t-Zr_1-x-yAl_xY_yO_2-x/2-y/2, due to phase transition stabilizers of CeO₂, Y₂O₃ and Al₂O₃. There are also some t-ZrO₂(SS) phases in the small-sized cellular submicro-Al₂O₃ crystals. After CSP heat-treated at 1450 °C for 1 h, it still retains cellular microstructure. Meanwhile, high-density nano- and supra-nano-ZrO₂ particles by in-situ nanoprecipitation are evenly distributed in intercellular ZrO₂ and intracellular Al₂O₃ grains. The special microstructures of the CSP before and after heat-treatment are difficult to be realized by previous methods. Therefore, the CSP approach has played an important guiding role in the preparation of cellular crystal powders and nanocomposite ceramics.