Coating of LiBH₄ and its effect on the decomposition of RDX and AP

The novel fuel additive LiBH₄ was introduced as an energetic component for its outstanding hydrogen content, perfect burning performance and high reactivity. In order to limit the hygroscopicity and to improve the stability in the air, LiBH₄ was coated on the surface with wax and polyester carbonate. The final product was characterized by scanning electron microscopy (SEM), X-ray photoelectron energy spectroscopy (XPS) and Raman spectroscopy, while the stability in air was investigated by regular checking of variations in weight. The results show that a uniform coating layer was formed on the surface of the LiBH₄, and the coverage was estimated from the boron content as approximately 82%. A healing effect was confirmed on defective surfaces exposed to air; the coating layer improves the relative stability by 50.7%. Furthermore, LiBH₄ as an additive to promote the thermal decomposition of 1,3,5-trinitro-1,3,5-trazinane (RDX) and ammonium perchlorate (AP) was explored by differential scanning calorimetry (DSC), in which the catalytic effects of pure LiBH₄ and coated LiBH₄ were compared, and indicated that the coating does not decrease the reactivity of LiBH₄. It is suggested that surface coating with some inert materials is a simple and effective method for improving the storage and performance of LiBH₄, while ensuring its reactivity.