Role of binders in reactive composites: A case study with spherical B/Pb3O4 particles

The strategic selection of appropriate preparation methods and binder strategies is crucial for enhancing the particle and combustion performance of pyrotechnic delay compositions (PDCs). This study, utilizing droplet microfluidics technology (DMT) and micron-scale raw materials, prepared spherical B/Pb₃O₄ composite particles with varying concentrations of fluorine rubber (F₂₆₀₄). The morphology, specific surface area, bulk density, flowability, friction sensitivity, thermal decomposition, and combustion performance of these microspheres were characterized. The results indicate that as the binder content increases, the particle size of the microspheres first decreases and then increases, the specific surface area decreases, and the bulk density increases, correlating with tighter binding of the reactant powders by the binder. Furthermore, tighter powder-to-powder binding results in a progressive decrease in the thermal decomposition peak temperature of the samples (from 404.2 °C to 346.4 °C). Additionally, increased binder content reduces the friction sensitivity and combustion rate of the samples, which is attributed to the energy absorption properties of the binder. Compared to the control group, the microsphere samples exhibit significantly enhanced bulk density, flowability, friction safety, and combustion delay precision, potentially improving the reliability of PDCs in ignition sequences.