Synthesis of aluminum nitride powder by carbothermal reduction of a combustion synthesis precursor

A new homogeneous mixing precursor of alumina and carbon (Al2O3 + C) was prepared by low temperature combustion synthesis (LCS) with aluminum nitrate (Al(NO3)3·9H2O), urea (CO(NH2)2), and glucose (C6H12O6·H2O) as starting materials. The precursor prepared was a foamy and porous mass due to the large amount of gases liberated in the combustion reaction and composed of nanosize particles. XRD analysis showed that this precursor consisted of amorphous alumina and carbon. The amorphous alumina in the precursor first transformed into γ-Al2O3, and then γ-Al2O3 was directly nitrided to yield AlN during the calcination process. The reaction temperature needed for a complete conversion for the precursor was about 1400 °C, which is much lower than that when using alumina and carbon black as starting materials. The synthesized AlN powder was composed of very fine particles and had good dispersability.