Low-Temperature Synthesis of Nano-AlN Based on Solid Nitrogen Source by Plasma-Assisted Ball Milling

Abstract

Plasma-assisted ball milling was carried out on the Al+C3H6N6 system and Al+C4H4N4 system, respectively. The phase structure, functional groups and synthesis mechanism were analyzed by XRD and FT-IR, and the differences in the synthesis process of nano-AlN with different solid nitrogen sources were discussed. The results show that C3H6N6 has a stable triazine ring structure, and its chemical bond is firm and difficult to break, so AlN cannot be synthesized directly by solid-solid reaction at room temperature. However, there are a large number of nitrile groups (-CN) and amino groups (-NH2) in C4H4N4 molecules. Under the combined action of plasma bombardment and mechanical energy activation, C4H4N4 molecules undergo polycondensation and deamination, so that the ball milling tank is filled with a large number of active nitrogen-containing groups such as N=, ≡N, etc. These groups and ball milling activated Al can synthesize nano-AlN at room temperature, with a conversion rate of 92%. SEM, DSC/TG analysis showed that the powder obtained by ball milling was formed by soft agglomeration of many fine primary particles about 50–80 nm. The surface morphology of the powder was loose and porous, and it had strong activity. After annealing at 800°C, the conversion rate of the Al+C4H4N4 system reached 99%.