Influence of Ap Particle Size on the Burning Characteristics of an/Ap-Based Composite Propellants

The burning characteristics of AN/AP-based propellants prepared with AP of various particle sizes were investigated to reveal the burning rate characteristics and the combustion wave structure model of AN/AP/HTPB propellant. The burning rate increases as the AP content increases, and the increment of the burning rate increases with decreasing the particle diameter of AP and rising of pressure. Some propellants prepared with small AP (below 69 μm) had a self-quenched or unstable combustion: partial flashing flame and flame propagation along the side of the propellant strand. The content of AP in the oxidizer of the propellant that had the self-quenched or unstable burning behavior was 0.4 and 0.6. The combustion pressures of these propellants did not remain constant and the pressure profiles showed violent variations. The burning rate characteristics of AN/AP-based propellants are remarkably affected by the particle size of AP and the AN/AP ratio. It was found that some of the AN/AP propellants prepared with fine AP would have a self-quenched or unstable burning behavior because of the remarkable heterogeneity of the combustion wave, i.e. the interference of the burning waves of AP and AN.