Carbothermal Synthesis of Aluminum Nitride Using Sucrose

Several aluminum oxides (α-Al₂O₃, θ-Al₂O₃, and AIOOH) were examined to study the differences in reaction behavior and powder characteristics during carbothermal nitrida-tion to AIN using sucrose and carbon black. The reaction conditions investigated were carbon-to-alumina ratio, reaction temperature, and time. Carburized sucrose resulted in Full conversion to AIN and produced a uniform powder morphology using a near-istoichiometric ratio of C:Al₂O₃ while carbon black required higher C:Al₂O₃ ratios (i.e., >4:1) for full conversion and led to agglomeration of the AIN powder. The most favorable reaction temperature was 1600°C, with the reaction time to full conversion being dependent on the type of Al₂O₃. The particle and agglomerate size of the AIN powders did not change significantly with reaction time. However, the particle size and morphology were strongly dependent on that of the initial AI₂O₃ with sucrose, whereas agglomeration of the AIN occurs when using carbon black. A solid–solid reaction mechanism is proposed.