Direct nitriding of large grains of aluminum with 2 mm size

Aluminum grains with 2 mm size have been completely nitrided in one batch process. Aluminum grains with added promoter(13.8 wt.% of Y(NO3)(3) . 6H(2)O) were almost completely nitrided by heating at 1300 degreesC for 2 h in N-2 atmosphere. It was deduced that aluminum was vaporized by heat of initial nitriding to react with nitrogen in vapor phase in a short period of time. Nitriding of large-sized aluminum was also attempted without additive. Electrolytically etched aluminum wires were also used as starting material. The aluminum wires without additive were also completely nitrided at 1300 degreesC by preheating at 600 degreesC for 2 h. It seemed that the oxide layer produced by a trace amount of oxygen in N-2 gas during preheating activated the initial nitriding. Finally, the complete nitriding of aluminum grains was achieved by preheating at 600 degreesC, without the additive. The oxygen content in the product was only 0.3%. in spite of the oxidation of the aluminum surface. This is because the surface area of the aluminum grains with 2 mm size is relatively small. (C) 2001 Elsevier Science B.V. All rights reserved.