Synthesis of AlN Powders by Carbothermal Reduction-Nitridation Reaction of Nonhydrolytic Al2O3 Gels with CaF2 Addition

AlN powders were prepared via carbothermal reduction-nitridation of nonhydrolytic Al2O3 gels. The XRD results showed that only AlN phase formed when the sample was calcined at 1450 °C in N2 flow of 80 ml/min, which was lower than that using Al2O3 powders as starting materials. The AlN powders were near-spherical particles and their particle size was around 400 nm. The effect of the CaF2 addition on the synthesis of AlN powders was aslo investigated. The results showed that the synthesis temperature of AlN powders colud decrease to 1400 °C, when 3wt% of atalytic agent CaF2 was added. Meanwhile, the particles size of AlN powders decreased, but their size distribution became wide range.