Samarium-doped ceria catalysts for boron-aluminum composite propellants: effect of synthesis method

Solid propellants based on ammonium perchlorate (AP) are widely used in rocket and missile propulsion systems due to their high energy density and reliable combustion characteristics. Although aluminum (Al) is the conventional metal fuel in AP-based formulations, boron (B) has gained increasing attention as a partial or full substitute owing to its significantly higher volumetric energy density. However, the low combustion efficiency of boron particles remains a critical challenge, making the use of catalysts essential to enhance the thermal decomposition of AP and overall propellant-burning performance. In this study, samarium-doped ceria (SDC20) catalysts were synthesized by three different methods including coprecipitation, templating, and autocombustion synthesis, and their effects on the thermal decomposition of AP and the burning rate characteristics of B-Al composite propellants were comparatively investigated. Thermal decomposition behavior was analyzed by thermogravimetry/differential thermal analysis, and apparent decomposition activation energies were calculated using the Kissinger method. Burning rate measurements were performed using a strand burner at different pressures and pressure exponents were determined. Results showed that SDC20 produced by the coprecipitation method had the highest catalytic activity, reducing the apparent decomposition activation energy of AP from 163.5 kJ mol–1 to 125.2 kJ mol–1. Burning rate tests further confirmed that catalyst addition significantly enhanced propellant performance and altered pressure sensitivity. These findings highlight the critical role of synthesis method on catalyst microstructure and catalytic efficiency in AP-based solid propellant systems.