Polyphenols-inspired interface modification and reduced agglomeration of solid propellants via a functionalized fluorine-containing organic substance coating layer

Interface modification of aluminum particles plays a crucial part in reducing the agglomeration during the combustion of solid propellants. In this study, the aluminum (Al) particles are pretreated with gallic acid (GA) to get Al@GA with an adhesion-favorable surface, which facilitates the further coating procedure. One new fluorine-containing organic substance is prepared, namely p-HFBA. The p-HFBA further coats the Al@GA to produce Al@GA/p-HFBA. The interface between Al@GA and the coating layer p-HFBA forms Al[sbnd]F bonds and induces a pre-ignition reaction with an aluminum oxide shell. Hence, the agglomerate size of propellants containing Al@GA/p-HFBA significantly decreases from 176.30 μm to 84.72 μm. The agglomerates volume is reduced by approximately 97 %. Additionally, more gaseous products investigated by TG-MS provide the Al particles with greater impetus (aerodynamic forces, F_ae), enabling them to leave the burning surface and reduce the residence time. The rise in F_ae and drop in adhesion force (F_ad) effectively reduce the agglomeration intensity according to the skeleton layer model. This work proves that interface modification can effectively enhance the combustion performance of aluminized solid propellants.