Thermal decomposition of zirconia-alumina gels prepared by the electrochemical method

Gels of zirconia, alumina and their mixtures were prepared by electrochemical reduction of aqueous solutions of zirconyl chloride and/or aluminum chloride. These gels were continuously deposited onto an electrode and precipitated at the bottom of an electrolytic cell. After freeze-drying, the products were amorphous. TG-DTA-MS analysis showed that they decomposed with loss of water and hydrogen chloride. Cubic zirconia appeared from gels heated to 600 °C. Mixtures of tetragonal zirconia and γ-alumina and of tetragonal and monoclinic zirconia and α-alumina formed from gels heated at 1000 and 1400 °C, respectively.