Preparation of AlN Powders by Vapor Phase Reaction of Al(i-Bu)₃-NH₃ System

Abstract

Preparation of AlN powders by vapor phase reaction of Al(i-Bu)₃-NH₃ system was studied by using a flow method. Mixing temperature of Al(i-Bu)₃-H₂ and NH₃ streams was 200°C and reaction temperatures were 600°-1400°C. AlN powders produced were not crystalline at low temperatures, but became slightly crystalline at high temperature. Particle size of AlN powders decreased with an increase of reaction temperature (600°C: 0.034μm, 110°C: 0.025μm, 1400°C: 0.017μm). The carbon content in AlN powders was minimum at around 1200°C. Heat treatment of as-synthesized AlN powders in H₂-NH₃ (10:1 in mol) at 1400°C for 2h decreased impurity oxygen and carbon from 18.8wt% to 4.5wt% and from 1.2wt% to 0.6wt% respectively. Crystallization of as-synthesized AlN powders by heat-treatment in the same atmosphere was appreciable above 1200°C, and heat treatment at 1400°C gave well crystallized AlN powders. Heat-treated AlN powders having the average particle size of 0.03μm densified to 90% theoretical without sintering aid by firing at 2000°C for 1h under N₂ of 10kg/cm².