Production of aluminum nitride from aluminum metal using molten fluoride

摘要

The production of aluminum nitride (A1N) from aluminum metal was investigated in this study. The nitridation of Al (in rod, powder, and thin-plate forms) was facilitated by dissolving the Al_2O_3 thin films formed on the Al samples with a molten fluoride mixture (KF-45 mol% AlF_3, KF, or LiF-50 mol% KF). A1N was formed when NH_3 gas was supplied to the Al sample (in both solid and liquid forms) wetted by molten fluoride mixture. The lowest temperature at which A1N was successfully produced was 773 K. No A1N was formed when N_2 or H_2-25% N_2 gas was supplied to the Al sample, even when a molten fluoride mixture was used. The reaction rate for the nitridation of Al powder increased with the temperature and reached 99% after 3 h at 1173 K. AlN thin films of 2-5 μm thickness were formed on Al thin plates (0.075-1.0 mm thick) at 873 K.