Understanding the role of ceric ammonium nitrate (CAN) in low-burning mixed nitrate ester propellants

In this study, the effect of ceric ammonium nitrate (CAN) as a lead-free additive on the combustion and thermal behavior of mixed nitrate ester propellant (MNP) was investigated. CAN was added to the propellant matrix in various contents adjusted to the content of lead-based additives in conventional propellants. Analysis of physicochemical properties showed that CAN-modified MNP has a homogeneous phase, indicating CAN is dispersed in the propellant matrix. The interaction of CAN with the propellant matrix was confirmed by XRD and FTIR characterization, which showed that CAN could modify the structural composition of the matrix. Analysis of mechanical properties showed that the addition of CAN reduce the compressive strength of MNP. Thermal and ballistic analysis showed that CAN at a low concentration (4% wt) can inhibit propellant decomposition by capturing NO∙ radicals using Ce⁴⁺ ions, as evidenced by an increase in the propellant ignition temperature to 186.27 °C and a decrease in the pressure exponent to 0.06 at lower combustion chamber pressures. The results of this study highlight CAN as a promising lead-free burning-rate modifier, with the ability to modify the pressure exponent and ignition characteristics.