(676e) Synthesis of Nanocomposites of Boron and Magnesium for Energetic Applications

Boron (B) has been considered as a promising reactive material for energetic applications such as solid rocket fuels and liquid propellants because of its potential ability to release enormous energy (58 KJ/g) during oxidation reactions compared to those of other metals like Aluminum (31 KJ/g) and Magnesium (25 KJ/g). Reducing the B particles into nanoparticulate form can lead to the improved oxidation kinetics owing to the resulting high specific surface area. However, also the high reactivity of B in nanoparticulate form reduces their energetic performance due to the formation of native oxide layer, which covers the significant mass fraction of the nanoparticle and acts as a diffusion barrier for the oxidizer. We need to channelize the transport of oxidizer by some means along with the reduction of native oxide layer. Magnesium (Mg) is an active metal with excellent combustion characteristics and comparatively lower melting and boiling points. So, if we use Mg along with B in energy systems, the preignition of Mg can induce the ignition of B by elevating the environment temperature and reducing the native boron oxide layer to form metallic B. This can enhance the oxidation kinetics of the B nanoparticles. Here, we are reporting the synthesis of nanocomposites of B and Mg having B in the core and Mg and Mg boride on the surface. We hypothesized that Mg could enhance the energy release from B nanoparticles along with their thermal stability. To prove our hypothesis, we performed various characterization experiments on Mg/B nanocomposites. Characterization was done with XPS and XRD methods to analyze the chemical bonds and the phases present in the nanocomposites. STEM-EDS in high angle annular dark-field (HAADF) was performed to demonstrate the elemental distribution of Mg and B in the nanocomposite. Thermal analysis (TGA, DSC) results provide information about the improved energy release, enhanced thermal stability, and higher reaction kinetics during the oxidation of Mg/B nanocomposites when compared to B oxidation under similar conditions. Also, particle size analysis using dynamic light scattering was performed to know about the particle size and its distribution. So, the Mg/B nanocomposite concept can be applied to the cutting edge design of the nanoenergetic materials for solid and liquid fuels.