Investigation of the agglomeration reduction mechanism of the aluminized HTPB propellant containing ferric perfluorooctanoate [Fe(PFO)3]

In this study, ferric perfluorooctanoate [Fe(PFO)₃] was used in the aluminized HTPB propellant to reduce Al agglomeration during solid propellant combustion, and the agglomeration reduction mechanism was experimentally demonstrated via the burning rate measurement, heat of explosion and Al agglomeration analysis. The behavior of the burning particles on the burning surface as well as the morphology and composition of the quenched burning particles were characterized by microscopic high-speed photography and X-ray photoelectron spectroscopy, respectively; the thermal decomposition properties and gaseous decomposition products of Fe(PFO)₃ were investigated by thermal gravimetry-differential scanning calorimetry joint analysis (TG-DSC), Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). The results show that Fe(PFO)₃ can significantly increase the burning rate of the aluminized HTPB propellant and reduce Al agglomeration. The aluminized HTPB propellant containing Fe(PFO)₃ exhibited a more efficient aluminum combustion process and smaller solid combustion product generation; the agglomeration reduction mechanism was revealed by the comprehensive effects of Fe(PFO)₃ on the thermal decomposition of AP and promotion of the thermite reaction with aluminum. It led to the special “immediate detachment upon ignition” phenomenon of Al particles in the propellant and caused the generation of smaller detached burning Al particles. The highly reactive gaseous decomposition products of Fe(PFO)₃ could reduce the accumulation of the generated Al₂O₃ on the burning Al particles.

In this study, ferric perfluorooctanoate [Fe(PFO)₃] was used in the aluminized HTPB propellant to reduce Al agglomeration during solid propellant combustion, and the agglomeration reduction mechanism was experimentally demonstrated.

Highly Reactive Metastable Intermixed Composites (MICs): Preparation and Characterization

Highly reactive metastable intermixed composites (MICs) have attracted much attention in the past decades. The MIC family of materials mainly includes traditional metal-based nanothermites, novel core-shell-structured, 3D ordered macroporous-structured, and ternary nanocomposites. By applying special fabrication approaches, highly reactive MICs with uniformly dispersed reactants, "layer-by-layer" or "core-shell" structures, can be prepared. Thus, the combustion performance can be greatly improved, and the ignition characteristics and safety can be precisely controlled by using a certain preparation strategy. Here, the preparation and characterization of the MICs that have been developed during the past few decades are summarized. Traditional preparation methods for MICs generally include physical mixing, high-energy ball milling, sol-gel synthesis, and vapor deposition, while the novel methods include self-assembly, electrophoretic deposition, and electrospinning. Various preparation procedures and the ignition and combustion performance of different MIC reactive systems are compared and discussed. In particular, the advantages of novel structured MICs in terms of safety and combustion efficiency are clarified, based on which suggestions regarding the possible future research directions are proposed.