The study of preparation of AlN powder

Highly purified fine AlN powder was synthesized with low oxygen content. The optimal raw materials were Al₂O₃ dehydrated from Al(OH)₃, carbon black, and AlN seed crystal, and their weight proportion was 1:0.5:0.01, respectively. Appropriate addition of AlN seed crystals might make the product finer. The order of the reaction was zero whose rate constants were 0.23 mol/L-s at 1400°C and 0.48 mol/L-s at 1500°C. AlN powder obtained at 1400°C was in the small size with regular shape and narrow size distribution. The product was fine too at 1500°C and a large amount of it possessed a hexagonal form. When the reaction was nearing completion, the baked powder was treated at depressed pressure to reduce the residual oxygen. Then the end-product was prepared containing 33.5% nitrogen, 0.4% oxygen, and 0.11% carbon (total) with an average particle size of 2-4 μm