Synthesis and sintering properties of aluminium nitride nanopowder prepared by the gas-reduction nitridation method

Aluminium nitride (AlN) nanopowder was successfully synthesized from transition alumina nanopowder via a new single-step nitridation process. A gas mixture of NH 3 –C 3 H 8 was employed as a reduction–nitridation agent, which enables direct nitridation of transition alumina at processing temperatures of 1200–1400 ° C. AlN powder prepared under typical reaction conditions was found to be phase-pure and nanocrystalline, with a specific surface area of 36.4 m 2 g −1 and a mean particle size around 50 nm. The AlN nanopowders produced could be densified to a pore-free state in conventional processing, without resort to the use of sintering aids. SEM observation revealed markedly small grain sizes in the sintered specimens compared with the commonly processed AlN.