Preparation of Al-5Li@FSG powders through fluorination-energetic modification to improve the comprehensive performance of alloy powders

Aluminum-lithium alloy powders receive extensive concern as metal fuel in propellants for high heat value and coefficient of combustion. However, the presence of highly active metal lithium leads to the instability of alloy powder, limiting its application in propellants. Herein, the fluorination-energetic modification is developed to solve the activity problem of aluminum–lithium alloy (Al-5Li, Li 5 wt%) powders and increase their energy level. The first fluorinated layer is constructed by fluorosilane and epoxy silane coating to achieve the modifiable and functional aluminum–lithium alloy (Al-5Li@FS). Afterwards, the energetic layer is coated on Al-5Li@FS surface by glycidyl azide polymer (GAP) to obtain the fluorination-energetic composite powders (Al-5Li@FSG). The microstructural and chemical composition characterizations of Al-5Li@FSG are performed by SEM, FTIR, XPS, TEM, and TOF-SIMS. TG-DSC results show that the coated alloy powders can exhibit excellent thermal properties with remarkably enhanced exothermic enthalpy and thermal weight gain. The Al-5Li@FSG shows significantly improved combustion performances with reduced ignition delay time and repressed agglomeration phenomenon. Furthermore, hydrophobicity, water-reactivity, and compatibility with propellant components are also well modified of the Al-5Li@FSG. This work provides a guideline for preparing aluminum–lithium alloy powders with remarkable stability, excellent combustion performance, compatibility, and high energy level.