Capsule structured Al/FeF3/AP energetic microspheres with enhanced combustion performance and energy release efficiency by a microexplosion reaction

The agglomeration and sintering of aluminum (Al) metal fuels lead to inadequate combustion and low energy release efficiency in the solid propellant systems. Herein, we assemble Al particles with gas generator of ferric trifluoride (FeF3) into capsule structured microspheres to detonate a microexplosion reaction by the evaporation -induced self-assembly technique, with encapsulating by ammonium perchlorate (AP) oxidant. The generated ternary Al/FeF3/AP microspheres achieved superior heat of combustion (12719.75 J g-1) and combustion temperature (1639.6 degrees C) owing to the full contact between components, reduced reaction transport distance, and the fierce shattering microexplosion combustion. Combustion mechanism analysis indicated that Al2O3 layer that hindered the oxidation reaction of Al was etched by the hydrogen fluoride (HF) from FeF3 decomposition, which caused the rapid splashing of nano Al clusters to detonate shattering microexplosion combustion. Furthermore, the ternary Al/FeF3/AP microspheres dramatically improve the combustion performance of hydroxy-terminated polybutadiene (HTPB)-based propellants and achieve a burning rate of 2.975 mm s-1, higher than most of the published HTPB/AP/Al propellants to date. The construction of Al/FeF3/AP microspheres exhibits a huge po-tential for the improvement of the propulsion power of rockets and weapons.