CARBOTHERMAL SYNTHESIS OF ALUMINUM NITRIDE USING SUCROSE

Several aluminum oxides (alpha-Al2O3, theta-Al2O3, and AIOOH) were examined to study the differences in reaction behavior and powder characteristics during carbothermal nitridation to AlN 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 AlN and produced a uniform powder morphology using a near-stoichiometric 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 AlN powder. The most favorable reaction temperature was 1600-degrees-C, with the reaction time to full conversion being dependent on the type of Al2O3. The particle and agglomerate size of the AlN powders did not change significantly with reaction time. However, the particle size and morphology were strongly dependent on that of the initial Al2O3 with sucrose, whereas agglomeration of the AlN occurs when using carbon black. A solid-solid reaction mechanism is proposed.