Study of Possibility of Obtaining Nanopowder Composition of "Aluminum Nitride – Boron Nitride" by Azide SHS Technology

Abstract

Processes and products of combustion of systems of "sodium azide – aluminum and boron halides " are studied. Halide salts AlF3, Na3AlF6, KBF4 and NH4BF4 are used as precursors of Al and B elements. The measured combustion temperature is in the range from 900 to 1800°C. It is established that the end product of combustion synthesis consists of several phases, not only the target phases (AlN and BN), but also the by-products (Na3AlF6, К2NaAlF6, NaF, KF), part of which is removed by water washing. The composite powder of AlN-BN is formed only in the case of AlF3 as precursor of Al; in doing so, it is formed with side, impurity product К2NaAlF6 or Na3AlF6. In the case of precursor Na3AlF6, the washed product of SHS may only be a by-product К2NaAlF6 or Na3AlF6 or along with the by-product, it may contain AlN or BN, but not their composition. That is explained by different combustion temperature.The structure formation of the composite powder is investigated. The obtained agglomerated nitride nano- and micropowders have an irregular and predominantly acicular shape with an average particle size of 50-170 nm in the agglomerates.