Influence of carbon on the synthesis of AlN powder from combustion synthesis precursors

AlN powders were synthesized by carbothermal reduction of combustion synthesis precursors. Water-soluble organics and carbon black were used as carbon sources. The effects of carbon on the synthesis of AlN powders were studied. Results showed that AlN powders were synthesized directly from γ-Al2O3 without γ-Al2O3 to α-Al2O3 phase transition when water-soluble organics were used as carbon sources, and the nitridation of the precursors could be completed at 1400 °C. However, AlN powders were synthesized from the nitridation of α-Al2O3 when carbon black was used as carbon source, and the reaction temperature for a complete conversion increased to 1500 °C. The particles of AlN powders synthesized with water-soluble organics was smaller than the particles of AlN powders synthesized with carbon black and their particle size distribution was sharper. The specific surface area of synthesized AlN powders increased with the increase of carbon content in the precursors.