A New Water‐Resistant Coating for AlN Powders

AlN powders were coated with a protective layer at temperatures between 1150‐1450°C in a vacuum by the reaction with SiO vapor. The waterproof property of the coated AlN powders was studied. The composition of the protective coating varied with the coating temperature. Si‐coated AlN powders at 1200°C showed excellent stability against hydrolysis. On the other hand, the coated layer was not observed when the AlN powders were treated at 1450°C. A silica layer was formed on the surface of the Si‐coated AlN powders by the oxidation treatment at 1000°C. These powders showed superior stability against hydrolysis compared to that of the commercially available silica‐coated AlN produced by the sol‐gel method. Compared to other processes used to coat AlN powders, the vaporization process using SiO vapor is simple and effective.