Enhancement of Nitridation in Synthesis of Aluminum Nitride Nanosize Powders by Pulsed Wire Discharge

High-purity aluminum nitride (AlN) nanosize powders were synthesized by pulsed wire discharge (PWD) of aluminum wires in nitrogen gas mixed with ammonia. The AlN content in the powders, which was determined by X-ray diffraction analysis, was increased by increasing the discharge energy. The highest AlN content of 98 wt% was obtained at the discharge energy of 360 J, and the average particle size was 30 nm. The increase in the AlN content at higher discharge energy can be explained by the energy deposited in the wire during the ohmic heating process. The number of micrometer-sized Al particles, which might be generated from liquid droplets, decreased by increasing the amount of energy deposited in the wire. The production rate of AlN powder was evaluated to be 46 g/kWh, which was 15 times higher than that obtained by the conventional arc discharge method.