Combustion Synthesis Of Nanocrystalline Boron Nitride And Nanocomposites

In this paper, various materials with different morphologies were prapared by changing the combustion conditions under low temperature/self-generated pressure or ambient temperature/pressure. Combing the experiments analysis results and the related reports, the formation mechanisms and the reactions conditions were studied. The main results were summarized as follows:1. Uniform rhombohedral boron nitride (rBN) with good crystallization were produced at a yield about almost 100% by the reaction between B₂O₃ and NaNH₂ at low temperature(500～600℃). The sample consists of triangle-flakes with lengths of the sides from 200 nm to 1 urn. The influences of the temperature, reaction time and reagent ratio on the formation of rBN were investigated.2. Boron nitride nano-flakes were successfully synthesized through a liquid-solid interracial combustion of liquid bromine and solid compacts of sodium borohydride and sodium amide. The influences of initial combustion temperature and ratios of NaBH₄: NaNH₂ were also investigated.3. Combustion reaction was developed to obtain nitride nanocomposites. Homogeneous mixtures of hBN and cubic TiN nanoparticles with good crystallization and high yields were first synthesized by simultaneous combustion reactions under ambient temperature/pressure or low temperature (400-600℃)/self-generated pressure. The combustion conditions were discussed. And the formation mechanisms were also simply proposed.