Effects of ZrO₂ Nanoparticles on the Microstructure and Thermal-protective Properties of PEO Coating on Al-12.5%Si Alloy

Abstract

PEO ceramic coatings including ZrO₂-Al₂O₃-SiO₂ in three phases were prepared on an Al- 12.5%Si alloy in electrolyte solutions containing ZrO₂ nanoparticles. The microstructures and phases of the coatings were analyzed by SEM and XRD, and the heat insulation performance and the thermal shock resistance of the coatings were investigated. The compactness of the coating increased significantly and the hindrance of the Si element on plasma electrolytic oxidation process was effectively weakened. The growth rate of the coating was improved substantially with the addition of ZrO₂ nanoparticles. The PEO ceramic coatings are primarily composed of SiO₂ and high temperature steady phases such as α-Al₂O₃ and c-ZrO₂. Both the content of c-ZrO₂ and the heat-insulating property of the coating increased significantly. The ceramic coatings with special microstructure and composition formed in the solutions containing ZrO₂ nanoparticles possess excellent heat insulation performance and thermal shock resistance

Keywords

Al-12.5%Si alloy / modified plasma electrolytic oxidation / ZrO₂ nanoparticles / heatinsulating properties / thermal shock resistance