Development of plasma process for preparing ultrafine aluminum nitride

UItrafine powders of aluminum nitride were produced by a de plasma jet. The evaporation process of the aluminum and the mechanism of the AIN synthesis were then studied. Al bulk and Al powder were used as raw materials. The cylinder type Al bulk was rapidly vaporized by an argon-nitrogen mixing plasma. As a result, ultrafine powders of AlN were prepared by the reaction of Al vapor with ambient ammonia gas. It was also observed that the conversion of Al into AlN was mainly affected by the injecting position and flow rate of the NH3 gas. When using Al powder as the raw material, crystalline AlN was obtained on the hot wall reactor, whereas amorphous AlN powder was obtained on the cold wall reactor. To increase the conversion, NH3 gas needs to be injected at a lower temperature because NH3 gas can easily be dissociated into molecular nitrogen and hydrogen at a higher temperature region. The powders observed were fluffy, white-colored with diameters ranging from 10 nm to 300 nm.