Carbon‐containing droplet combustion–carbothermal synthesis of well‐distributed AlN nanometer powders

Abstract

AbstractA novel three‐step technique was employed to synthesize the well‐distributed AlN nanopowders. First, the hollow spherical precursor particles with an average diameter of 2–5 μm, consisting of an amorphous structure mixture of Al2O3 and C, was prepared by carbon‐containing droplet combustion method by using glucose, urea, and aluminum nitrate as starting materials. The carbothermal reduction and nitridation (CRN) was carried out at 1500°C under N2 flow for 2 h and subsequently the CRN product was calcined at 700°C in air for 1 h to remove residual carbon and transform the CRN product to high‐purity AlN powders consisting of nanostructured hollow spheres. The formation mechanism of precursor and AlN hollow spheres was discussed in detail. The AlN powder exhibited well‐distributed spherical particles with a size of 30–50 nm and good sinterability. After additive‐free and pressureless sintering at 1800°C for 2 h, the relative density of the sintered AlN sample was measured to be 99.02%.