Effects of Magnesium Catalyst on the Nitridation of Aluminum Melt in the Synthesis of Aluminum Nitride Powder

Abstract

Aluminum nitride (AlN) powder was easily synthesized by the direct nitridation of Al melt containing ~20 wt.% Mg catalyst and the nitriding behavior was investigated by thermodynamic calculation and through observations of electron microscopy and X-ray diffraction. The addition of Mg catalyst decreased the nitriding temperature below 1,000oC, which is comparable to the high nitriding temperature of 1,400oC required in carbothermal method. It was caused by a significant increase of the solubility of nitrogen gas due to the increase of Mg catalyst in Al melt. The dissolved nitrogen gas met Mg catalyst and was transformed into metastable Mg3N2. Finally the metastable phase reacted with Al to AlN.