Effect of starting materials’ dispersion on the properties of AlN powder synthesized by carbothermal reduction and nitridation

This study examined the effects of starting material dispersion on the formation of AlN powder synthesized by carbothermal reduction-nitridation (CRN) route. After preparing aqueous and non-aqueous slurries containing 6.5 vol. % of Al2O3 and carbon black powder with/without a dispersant, the particle dispersion was evaluated by sedimentation and viscosity measurements. The zeta potential was also measured to determine the optimal dispersion conditions for electrostatic repulsion because carbon black is challenging to disperse in water, owing to its low surface charge and poor wettability. The aqueous slurry prepared with 5 wt. % Gen0451 dispersant at pH = 10 showed the highest degree of dispersion. Complete AlN conversion was achieved by nitridation at 1600 °C for 6 h under 10 L/min N2 flow. This result clearly showed the importance of starting material dispersion on the synthesis of AlN by CRN, demonstrating the feasibility of aqueous processing instead of conventional solvent-based processing.