Synthesis of highly sinterable AlN nanopowders through sol-gel route by reduction-nitridation in ammonia

Abstract

Abstract Aluminum nitride (AlN) nanopowders were synthesized through sol-gel route by reduction-nitridation reaction in a temperature range of 1000 °C-1300 °C in NH 3 for 2 h. Effects of combustion atmosphere on characteristics and nitridation reaction of the precursor were systematically investigated. It was found that the precursor combusted in argon, with the features of higher carbon content and smaller specific surface area, was completely converted to AlN after being calcined at 1300 °C without additional carbon removal process. The TEM and FESEM images showed that the completed nitridation product was primarily composed of nearly spherical AlN granules with sizes of 20–30 nm. In addition, the formation process and potential mechanism of AlN low-temperature synthesis were proposed on the basis of thermodynamics calculations. The AlN ceramic was prepared by calcining the AlN green body at 1600 °C for 4 h with pressureless and additive free sintering. The relative density and Vickers hardness of the sintered sample were calculated to be 98.5% and 11.97 GPa, respectively, which attested to excellent sinterability of the synthesized AlN nanopowders.