Fabrication of ZrO2-Al2O3 hybrid nano-porous layers through micro arc oxidation process

Zirconia-alumina layers, with a pores size of 40-300 nm, were fabricated via micro arc oxidation method for the first time. The layers were grown under alternative current in the electrolytes of ZrOCl2 salt. They consisted of α-Al2O3, γ-Al2O3, monoclinic ZrO2, tetragonal ZrO2. Increasing the voltage resulted in higher zirconium concentrations in the layers. A porous structure was obtained when the layers were grown under intermediate voltages. Microcracks were observed to appear when the applied voltage increased. Finally, a formation mechanism was proposed with emphasis on the chemical and the electrochemical foundations.