Facile Grinding Method for Preparing Nano-Cu-Cr-Fe Composite Metal Oxides with Enhanced Catalytic Activity for Thermal Decomposition of Ammonium Perchlorate

Ammonium perchlorate (AP) is a commonly used oxidant for solid propellants, and improving the thermal decomposition performance of AP has been the focus of research, as its thermal decomposition performance directly affects the performance of the propellant. Among a variety of catalysts, nanocomposite metal oxides have demonstrated a significant role in facilitating the thermal decomposition of AP. In this study, Cu-Cr-Fe ternary metal oxides with different molar ratios (5:2:8, 5:4:6, 5:6:4, 5:8:2) were prepared by a facile mechanical grinding method to investigate their catalytic effect on the thermal decomposition properties of AP. The structure and morphology of Cu-Cr-Fe ternary metal oxides were investigated using X-ray diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the catalytic effect of different ternary catalysts on the thermal decomposition performance of AP was also investigated using thermal weight (TG) and differential scanning calorimetry (DSC) techniques. The results show that Cu-Cr-Fe ternary nanocomposite metal oxides with a molar ratio of 5:2:8 prepared by mechanical grinding exhibit excellent catalytic effect on the thermal decomposition of AP, as well as nanometallic oxides (Cu-Cr-Fe = 5:2:8) prepared using the co-precipitation and physical mixing methods. Furthermore, the ternary Cu-Cr-Fe (molar ratio of 5:2:8) composite metal oxide prepared by mechanical grinding resulted in a significant decrease in the thermal decomposition temperature of AP, which decreased from 441.3°C to 352.5°C, the heat of decomposition increased from 941 J/g to 1680 J/g, and the Gibbs free energy of AP decreased from 199.8 kJ/mol to 173.2 kJ/mol. This demonstrates the good synergistic catalytic effect between CuO, Cr2O3 and Fe2O3 nanoparticles, which is expected to facilitate the application of ternary nanocomposite metal oxides in the field of solid propellants.