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

Abstract

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@ZrO2 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 ZrO2 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 ZrO2 holds its metal properties with low infrared emissivity over 500 °C. The Al@ZrO2 composite could be used in a higher temperature range as a low infrared radiation material.