Kinetic Studies on Crystallization and Grain Growth of Amorphous Al2O3-ZrO2 Powder

Nanocrystalline Al2O3-ZrO2 powders were prepared through controlled crystallization of amorphous phase, and kinetic studies on crystallization and grain growth were carried out. Based on Kissinger equation, the activation energies for crystallization were determined to be 981.8 kJ·mol-1 for (Zr0.94Y0.06)O1.88 and 1364.1 kJ·mol-1 for α-Al2O3. Average size of crystallite was obtained by Scherrer equation according to FWHMs in XRD peaks; the grain growth was slow below 1100°C, and turned severe at higher temperatures. The appropriate calcination temperatures was determined to be 1100°C, at which stable phases were formed and further severe grain growth can be restrained. SEM micrograph of Al2O3-ZrO2 powder after calcination at 1100°C revealed uniform distribution of spherical particles with size of about 20 nm, close to that determined by XRD results.