Positive effects of organic fluoride on reduction of slag accumulation in static testing of solid rocket motors of different diameters

The serious slag accumulation produced by the combustion agglomeration of aluminum (Al) in solid composite propellants always reduces the specific impulse of the solid rocket motors and affects their reliability. The actual effects of the organic fluoride OF on reducing slag accumulation under solid rocket motor conditions are systematically investigated by adding the OF into HTPB propellants and performing a series of tests. The XRD patterns and SEM observation show that the slag is mainly composed of the unreacted Al and alumina (Al₂O₃), and most of the slag has a lamellar structure. OF noticeably reduces slag accumulation and increases the combustion efficiency of aluminum in the Φ315 and Φ480 motors. When adding 2 wt% OF into HTPB propellants, the mass and residual aluminum content of the slag in the Φ315 motors decrease by about 26.5% and 34.9% respectively, and the mass and residual aluminum content of the slag in the Φ480 motors decrease by about 42.7% and 57.2% respectively. Furthermore, the characteristic slag size decreases from greater than 30 cm to smaller than 3 cm in the Φ480 motors. The throat ablation has also been weakened after adding OF in the formulations.