Application of ball milling Al/FCOs particles in solid propellant combustion

The agglomeration of aluminum particles usually occurs on the burning surface of aluminized composite propellants. It leads to low propellant combustion efficiency and high two-phase flow losses. To overcome the agglomeration, especially the generation of large agglomerates, the aluminum powder was modified by a fluorine-containing organic substance(FCOS) using ball milling method before adding into the propellant. The oxidation and ignition performance, as well as the propellant agglomeration and combustion properties of virgin aluminum and Al/FCOS composites particles were compared. It is observed that the modified particles can be more quickly ignited, and more gaseous products were produced, breaking the large particles into smaller size, which can decrease the agglomeration. The adding content of Al/FCOS was varied and results show the 8.5 wt.% has stronger effect on agglomeration reduction compared with 17 wt.%. The linear burning rate above 5 MPa is in the order of 8.5 wt.% Al/FCOS > Al > 17 wt.% Al/FCOS, while the pressure exponent of 17 wt.% Al/FCOS is the lowest. The FCOS inclusion changes the oxide shell properties of aluminum particle during ignition. Results of this study are expected to enrich in the frame of aluminum agglomeration reduction.