Investigation on preparing boron nitride by nitriding pureboron at 1200–1550 1C

Boron nitride (BN) was prepared by nitriding pure boron (B) deposited on carbon substratesby chemical vapor deposition (CVD). Thermodynamic analysis of preparing BN by nitriding CVD B at1200–1550 1C was firstly performed. And then, the effects of nitridation conditions, includingtemperature, nitridation atmosphere and CVD B microstructure, on the conversion of B to BN wereanalyzed by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-rayphotoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Results show that theconversion degree of B to BN firstly increased and then slightly decreased with rising temperature. Thenitridation degree was controlled by mutual actions between the nitridation of B and consumption of theeffective nitrogen source (NH3). The morphology of products and the reaction mechanism between B andN were influenced by nitridation temperature. At high temperatures (1400–1500 1C), BN with highlyordered microstructure was produced. On using N2–H2 as nitridation atmosphere instead of NH3–H2–N2, no BN was obtained in the studied temperature range. The microstructure and component of BNobtained in nitridation process were little affected by the microstructure of CVD B.