Modified flake Al powder by ZrO2 coating as potential low infrared radiation material for high temperature over 500 °C

Electronic structure adjustment on materials' surfaces often leads to materials obtaining novel performances. Flake Al powder is a classical low infrared emissivity material at room temperature. However, this powder shows intense infrared radiation over 500 °C due to its high-temperature oxidation , which restricts flake Al powder's application as low infrared radiation material in higher temperatures. For this reason, the Al@ZrO 2 composite was prepared by a solvothermal method to improve its thermostability. This composite can be used as low infrared radiation material over 500 °C for the long term, even at 700 °C for a short time. According to the experimental and theoretical investigation, a delocalization bond of Al–O–Zr is formed in the interface between the Al surface and ZrO 2 so that the Al surface's electronic structure is adjusted. This change of electronic structure weakens the electroaffinity of Al atoms to bond with the electron-rich groups, and the oxidation reaction of Al needs to proceed in a higher-temperature range. In this case, flake Al powder coating with ZrO 2 holds its metal properties with low infrared emissivity over 500 °C. The Al@ZrO 2 composite could be used in a higher temperature range as a low infrared radiation material.