Enhancing combustion performance of composite propellants through chemical modification to bond nano-aluminum powder and RDX building blocks for energy release coupling

Abstract

Due to the difficulty in establishing organic functional groups on the surface of aluminum powder, the effective combination of aluminum powder with other oxidizing particles is inhibited, thereby limiting its energy characteristics. By introducing effective functional groups on the aluminum powder surface that can form chemical bonds, it is possible to establish links between particles and achieve three-dimensional growth of nano-aluminum powder on various oxidizer particle surfaces. In this study, we propose the creation of two building blocks: nano-aluminum (nAl) modified with 3-mercaptopropyltrimethoxysilane (MPTS) and 1,3,5-trinitro-1,3,5-triazine (RDX) modified with tannic acid (TA). Through the chemical bonding of these two building blocks, three-dimensional growth of nano-aluminum powder on the RDX surface was achieved, resulting in the preparation of RDX@Al. The results demonstrate that RDX@Al effectively reduces the activation energy of RDX, showcasing the energy coupling and synergy between RDX and nAl. Adding RDX@Al to composite propellants significantly improves the combustion performance of the propellants. Due to the shortened mass and heat transfer distances between RDX and nAl, the combustion rate of the propellant increased by 38 %, and the combustion intensity was also enhanced. Additionally, the size of the condensed phase combustion products from the propellant was reduced by 59.8 %. This work provides new insights into the design of composite energetic materials and the elucidation of the combustion mechanisms of composite solid propellants.