Thermal decomposition and combustion studies of catalyzed AN/KDN based solid propellants

Effects of catalyst on the thermal decomposition were envisaged for AN and AN/KDN mixtures as an oxidizer and on the composite propellants based on them. AN/KDN based oxidizer samples were prepared in the ratios of 75/25 and 50/50 by a co-crystallization method. Propellants were formulated based on AN and AN/KDN mixtures as an oxidizer, and HTPB as a fuel binder with the addition of catalyst. The catalysts used for present studies are, (i) cupric (II) oxide (CuO) and (ii) copper–cobalt based metal oxide (Cu–Co*). For all samples, 2% by weight of catalyst was added to the total weight of the samples. Thermal decomposition and burning rate studies were carried out for prepared propellant samples. All prepared oxidizers and propellants samples are subjected to DSC/TG studies using Simultaneous Thermal Analyzer (STA), while strand burners are used for burn rate determination of propellants in pressure regimes 100–4760 kPa and at sub-atmospheric pressures regimes (<100 kPa). Evolved gas analysis-QMS (EGA) was also performed to understand the decomposition mechanism of propellant samples. Propellants based on AN/KDN (50/50) in the presence of Cu–Co* showed the highest burning rate and also sustain combustion up to 40 kPa. Propellants based on CuO was also observed to enhance the burning rate but lesser as compared to the propellants based on Cu–Co*.