Nitridation reaction of aluminum powder in flowing ammonia

AlN powder was prepared by the nitridation of metal Al in flowing NH3. The effects of reaction temperature and the temperature gradient of the reaction zone on the nitridation of Al were investigated. Comparative analysis of products formed in different reaction zones and reaction temperatures suggested that the nitridation reaction of liquid Al particles in flowing NH3 was through the following mechanisms: NH3 dissociated into reactive nitrogen (N) and hydrogen (H) radicals at the surface of Al particles. N reacted with Al to form AlN, while H promoted the decomposition of NH3, which provided enough energy for the dissociation of NH3. All of the experimental results had been discussed on the basis of this model, which indicated high reaction temperature or positive temperature gradient was favorable for the nitridation of Al. (C) 2003 Elsevier Science Ltd. All rights reserved.