Interfacial regulation of Al-5Li alloy powders via a composite TPW coating for enhanced compatibility and performance in composite solid propellants

A TMPO/mPEG/WAX synergistic interface was successfully constructed on Al-5Li alloy powders. • The surface coating significantly improved the hydrophobicity and compatibility of Al-5Li. • Enhanced optical emission confirmed increased combustion activity of coated particles. • The surface coating improved both the mechanical properties and combustion performance of composite propellants. Focusing on the issues of poor compatibility and interfacial instability of Al-Li alloy powders in composite solid propellants, this study develops a composite coating system composed of trimethyl phosphate (TMP), methoxy polyethylene glycol (mPEG), and paraffin wax (WAX) (denoted as TPW) to regulate the particle surface interface. The coating structure and composition are characterized by TEM, ToF-SIMS, and XPS. The results indicate that TPW forms a relatively continuous and uniform interfacial layer on the particle surface. This interfacial structure improves the compatibility between Al-5Li and typical propellant components, namely hydroxyl-terminated polybutadiene (HTPB) and ammonium perchlorate (AP), stabilizing the thermal decomposition behavior and improving the mechanical performance of the propellant. Meanwhile, the combustion heat of the powder does not decrease significantly after coating, and it shows excellent combustion response characteristics. With this interfacial structure in place, a practical balance can be achieved among compatibility, structural integrity, and energy output, offering a new approach for applying Al-Li alloy powders in composite propellants. Download: Download high-res image (152KB) Download: Download full-size image