Thermal decomposition and combustion characteristics of HTPB-coarse AP composite solid propellants catalyzed with Fe2O3

Abstract

ABSTRACTMany factors and their mutual interactions induce complexity in the combustion of hydroxyl-terminated polybutadiene (HTPB)–ammonium perchlorate (AP)–ferric oxide (Fe2O3) composite solid propellant (CSP). Among them, we investigated exothermicity of coarse AP decomposition for thermal decomposition and high-pressure combustion of HTPB-AP. Thermal decomposition of coarse AP was characterized by high twin-peak exothermicity, while HTPB-AP decomposed in single-stage at 329°C. Coarse AP improved thermal decomposition due to significant first-stage exothermicity. High exothermicity and predominance of coarse AP dominate thermal decomposition of CSP. Fe2O3 catalyzed decomposition of AP by shifting second exothermic peak to lower temperature and releasing more heat. Fe2O3 increased the burning rate of HTPB-AP and the highest burning rate was achieved for 1 wt % nano-Fe2O3 of average size 4 nm. Similar results for milli- (average size 200 μm) and micro-Fe2O3 (average size 2 μm) were recorded at higher concentrations. Exothermicity of coarse AP and catalytic activity of Fe2O3 on AP speed up subsurface processes and help in the enhancement of burning rates.