Abstract: The effect of NH₄Cl/KCl as the additives on the nitridation of aluminium powders was investigated.
Pure nanosized AlN powders were obtained after nitriding Al powders at 1000℃ for 5h when NH₄Cl/KCl was used as the additives.
TG/DSC analysis was used to record the nitridation process of aluminium powders when different additives such as NH_4Cl, KCl and NH₄Cl/KCl
were used. The resulting powders under different experiment conditions were characterized by XRD, SEM and XRF. The results show that NH₄Cl
can lower the nitridation temperature and prevent the melting and coalescence of reactant Al particles, thus nanosized AlN particles will be
obtained. Apertures generated by the evaporation of KCl avoid the formation of a dense nitride layer on Al particles and enable the diffusion of NH₃
to complete the nitridation of Al. NH₃ as the reactant gas can eliminate the effect of moisture impurity introduced by additives. NH₄Cl/KCl is
a good additive with low residue and for the production of high purity AlN.

Key words: NH₄Cl, KCl, aluminium, nitridation