Novel synthesis of fine γ-AlON powders from the hydrolysis of Al metal

In this study, fine aluminum oxynitride (γ-AlON) powder was synthesized by solid-state hydrolysis byproduct for the first time, through the in-depth research of the hydrolysis of metal Al powder. It was found that hydrolysis begins on the surface of the Al particles, the initial solid-state hydrolysis byproduct is AlOOH and then Al(OH)₃, and during the reaction stage, a unique core-shell structure with hollow outer core composite precursor is formed. Pure phase AlON powder can be synthesized by utilizing a composite precursor with an appropriate Al₂O₃/Al ratio (Al₂O₃/Al=10.27) under a flowing N₂ atmosphere. The core-shell structure shortens the diffusion distance between raw materials and reduces the nitridation temperature (1700°C). Furthermore, the unique hollow structure composite precursor makes some of the synthesized AlON powders also have a hollow structure, which is conducive to powder crushing, and fine nanoscale (D₅₀=292 nm) powders can be obtained only grinding process. The combination of Al-H₂O reaction and direct nitridation method has developed a new synthesis method of AlON powder, and also provides a new way for the recovery of solid-state hydrolysis byproduct of metal Al powder.