Fabrication of bulk amorphous and nanocrystalline Al2O3-YSZ materials

This study reports a simple method for the preparation of bulk amorphous materials by rapid solidification of their crystalline powders. Bulk amorphous Al2O3-YSZ materials have been successfully prepared by atmospheric plasma spraying (APS) using Al2O3-YSZ mixed crystalline powders near eutectic composition. Nano-crystalline Al2O3-YSZ materials with homogeneous nanostructure were achieved by heat treating bulk amorphous Al2O3-YSZ materials at 1050 °C. When annealing temperature was above 1250 °C, the lotus leaf structure was formed because of connection between large numbers of Al2O3 nano-grains due to sintering. Therefore, it can be concluded that annealing temperature of amorphous Al2O3-YSZ materials need to be controlled between Tc (onset crystallization temperature) and 1250 °C avoiding large area of sintering to achieve homogeneous nanocrystalline ceramics.