Carbothermal Synthesis of Aluminium Oxynitride (ALON) Powder: Influence of Starting Materials and Synthesis Parameters

摘要

Carbothermal synthesis of cubic aluminium oxyni-tride (ALON) have been performed in a graphite furnace at different temperatures (1700-1860℃) and pressures (0.1-10 MPa). The products were characterized by XRD, SEM and elemental analyses, and the overall compositions were determined by reoxidation in air. The control of excess nitrida-tion was a crucial task in the preparation of ALON. A two-step procedure, first annealing at about 1550℃ then at about 1800℃, was found to be effective to this end. CO additions to the N_2 gas stimulated ALON formation, but a pressure increase resulted in a lower nitridation rate. The particle size and morphology of ALON depended on raw material type and synthesis parameters such as temperature program, pressure, CO content in the N_2 gas, and sample compartment type. Thermody-namic calculations in the Al-O-C-N system have been performed in order to explain the experimental results.