Preparation of ZAO powder and investigation on its infrared emissivity

According to the basic infrared stealth mechanism of low infrared emissivity powders, the ZAO powder materials were prepared by liquid coprecipitation method, and the starting materials were Zn(NO₃) 6H₂O and Al(NO₃)₃9H₂O. The process parameters were obtained, and the relationship between technology parameters and infrared emissivity was investigated. The temperature of thermal treatment, crystal structure and surface micrograph of ZAO powder was analyzed by the help of TG-DTA, XRD and SEM. The infrared stealth performance of ZAO powder was studied by IR-2 emissivity spectroscopy. Results showed that the infrared emissivity was the lowest when pH was 8.0, calcination temperature was 1100°C, calcination time was 2 h, and the Al₂O₃ doping content was 3% (mass percentage). The crystal structure of doped ZAO powder was lead-zinc, and there exists distortion of crystal lattice in nanocrystalline ZnO. The average particle size was 10 μm. The lowest infrared emissivity reached to 0.61 at between 8 μm and 14 μm. It means that the ZAO powders will be excellent infrared stealthy materials.