Mixing Safety of Composite Solid Propellant Slurry in a Blade-Free Planetary Mixer

Blade-Free Planetary Mixer (BFPM) can rapidly and efficiently mix highly viscous materials because of the strong centrifugal forces generated by the planetary motion of the mixing vessel. The safety of energetic propellant slurry during BFPM processing is critical. In this work, the mixing performance and process safety of composite solid propellant slurry in a BFPM were investigated through morphology observation, mixing index analysis, temperature measurement, rheological testing, mechanical sensitivity evaluation, and thermal analysis. The results showed that the BFPM achieved safe, efficient, and uniform mixing of the slurry. Under the baseline condition of 1000 rpm, the mixing index reached 95.73% after 24 min, and the slurry temperature increased to only 31.1 °C. The influence of BFPM processing on slurry safety was mainly reflected in the spatial redistribution of energetic solid components and the solid-liquid mixing state. And mechanical sensitivity tended to increase in regions of higher apparent viscosity. Increasing the rotational speed and adopting alternating rotation promoted particle dispersion and reduced local apparent viscosity, but an excessively high rotational speed reduced thermal stability. Overall, 1200 rpm combined with alternating rotation was identified as the most suitable operating condition. This work provides a practical basis for the safe and efficient BFPM processing of energetic propellant slurries.