Reactive plasma atomization of aluminum nitride powder

Experiments were performed to synthesize AlN powders by reacting Al with N using a conventional DC arc plasma as a heat source. Attempts to form AlN powders by feeding Al powder into an argon/nitrogen plasma open to the atmosphere produced mainly aluminum oxide. Subsequent experiments were run inside a chamber which was backfilled with nitrogen. The nitrogen environment suppressed the formation of aluminum oxide, but little AlN was formed by using Al powder as the feedstock material. A furnace and crucible assembly was designed to feed molten Al directly into a DeLaval nozzle attached to the face of the DC arc plasma gun. The submicron powders formed using this arrangement show a significant increase in the level of AlN formation. The presence of AlN was verified by chemical analysis and X-ray diffraction. Results were dependent upon chamber pressure, plasma velocity and molten liquid feed rate. The experimental parameters, equipment design and results will be reported in detail. The effects of atomization, vaporization and condensation on the reaction product will be discussed.