Some features of the formation of A1N during the reduction-nitriding of ultrafinely divided alumina

A study was made of the process of carbothermic reduction-nitriding of ultrafinely divided alumina in the temperature range 1200–1450‡C. It was established that the carbothermic reduction-nitriding of ultrafinely divided alumina is accompanied by the formation of intermediate oxycarbide and oxynitride phases. This is a result of the alumina reduction process having a stepwise character and of the formation of solid solutions in the AI-O-N system. It is shown that the resultant aluminum nitride is in the form of polycrystalline particles. The sizes of the particles and of the grains in them are 1–3 and 0.01–0.2 Μm, respectively. With rise in nitriding temperature, the particles decrease and the grains increase in size.