Aluminized Composite Propellants: Surface Morphology, Aluminum Agglomeration and Condensed Combustion Products

An aluminized composite propellant was experimentally investigated to examine its combustion characteristics, surface morphology, and the formation of condensed combustion products (CCPs). Burn-rate measurements conducted in a Crawford bomb over 2–7 MPa yielded a pressure exponent of 0.34. The surface morphology and elemental composition were characterized using scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS) for both unburnt and extinguished propellants. For extinguished propellant, the aluminum was found to be distributed over fine and coarse ammonium perchlorate (AP) particles. The presence of binder melt and aluminum agglomerates was also observed on the surface of the extinguished propellant. CCPs from end-burning and port-burning configurations were collected using a closed quench bomb at different quench distances and analyzed using laser diffraction particle size analyzer, SEM–EDS, and X-Ray diffraction. The particle size distribution exhibited a broad multimodal range from 0.1 μm to 400 μm. Fine alumina particles were predominantly spherical, whereas coarse particles consisted of irregular agglomerates and fragmented alumina structures formed through particle coalescence. The results establish correlations between burning-surface features and CCP evolution under varying combustion environments.