Synthesis of Fine AlN Powders by Foamed Precursor-assisted Carbothermal Reduction-nitridation Method

A modified carbothermal reduction-nitridation(CRN) method was proposed to synthesize fine AlN particles using γ-Al2 O3 and sucrose as raw materials which were pre-treated as cellular foams. The reaction procedure and the produced AlN were investigated by XRD, SEM and TEM. XRD result suggests that γ-Al2 O3 transferred into AlN without transformation into α-Al2 O3. HRTEM shows that γ-Al2 O3 particles are covered by amorphous carbon from sucrose inhibiting the transformation of α-Al2 O3 from γ-Al2 O3 in the synthesis procedure. The foamed structure is of benefit to the diffusion of N2 and the produced CO. The minimum reaction temperature is 1450 ℃ for full conversion of Al2 O3 to AlN. SEM photographs show the particle size of synthesized AlN is 50 nm. This study demonstrated an efficient way to synthesize fine AlN powders which are urgently required for the manufacture of advanced AlN ceramics.