A functional fluorine (F)-containing oxidiser of nano-networked NH4CuF3 to improve the combustion efficiency of Al powder

Abstract

Aluminium (Al) powder is the most common solid fuel component in metastable intermolecular composites (MICs). It is used in the field of propellants to provide energy for the flight of rockets and missiles. However, the passivation layer overlaying its surface hinders its energy release. Using fluorine (F)-containing oxidisers may etch the passivation layer, enabling Al to achieve a more direct redox process and improving its energy-release capacity. Herein, NH₄CuF₃, which has nano-network structure, was synthesised through the solvo-thermal method, and n-Al was filled into the nano-pore channels using a simple ultrasonic mixing method to form a new n-Al/NH₄CuF₃ MICs with excellent dispersion and interfacial contact. The thermal decomposition process of NH₄CuF₃ was investigated, and the results showed that NH₄CuF₃ could release hydrogen fluoride (HF) and ammonia (NH₃) gaseous products. The passivation layer on the surface of the Al powder was etched by HF, and the abundance of gaseous products during the reaction of n-Al/NH₄CuF₃ Extended the combustion region. This can enhance air capture in the reaction system, minimise reaction sintering and aid in performing external work. Furthermore, n-Al/NH₄CuF₃ exhibits a lower onset reaction temperature, shorter ignition delay time and greater external work ability than n-Al/CuF₂ and n-Al/CuO.