Promoted ignition and combustion of nano-boron powder by transition metals catalysis

Boron possesses a high calorific value, but the surface oxide hinders the diffusion of oxygen during combustion, causing ignition difficulties and incomplete combustion. Herein, eight transition metals were used to promote the ignition and combustion of nano-boron powder (nB) via the catalysis, among which Mo possesses the best performance. Compared with nB, the combustion heat of Mo/nB was increased by 19.80 MJ/kg and the initial oxidation temperature was reduced by 186.3 degrees C. Finally, the combustion mechanism of Mo/nB was proposed: A three-layer structure is formed after Mo/nB ignited. MoO3 produced by Mo oxidation acts as the catalyst to promote the oxidation of nB by serving as oxygen transport carrier to release adsorbed O2. Furthermore, the expansion of O2 under heat destroys the dense surface oxide layer to open an oxygen transport channel for (BO)n in middle layer, extending the stable combustion time, with the energy of nB released fully.