Fine interfacial control mechanism of ammonium perchlorate and aluminum powder: Thermal reaction characteristics and kinetic studies

To gain insight into the fine interfacial control mechanism exhibited by oxidant-coated Al powder to improve combustion performance, we prepared Al/AP and Al@AP composite fuels using ball milling and spray-drying technology. The thermal reaction characteristics, AP decomposition behavior, and decomposition reaction pathways of Al/AP and Al@AP composite fuels were investigated using thermal analysis and Ab Initio Molecular Dynamics (AIMD) calculations. Under the influence of fine interfacial control, the low-temperature decomposition heat release peak of AP was delayed by 25.5 ℃, while the high-temperature decomposition peak was advanced by 36.2 ℃, leading to an increase in the decomposition heat release of AP from 410.7 J/g to 1068.7 J/g. Compared to the unclad structure, the apparent activation energy of AP in low-temperature decomposition increased, and slightly decreased during high-temperature decomposition in the Al@AP composite fuel. The physical model of AP decomposition shifted to the model with higher degrees of freedom and a faster diffusion rate, characterized by rapid bidirectional diffusion at the interface. Furthermore, due to fine interfacial control, the oxidation reaction pathway of Al has been altered, changing from the final products of AP decomposition (O₂, Cl₂, etc.) to the direct oxidation of AP decomposition intermediates (HClO, ClO₂, etc.). This accelerated and strengthened the oxidation reaction process of Al. As a result of these performance improvements, the final combustion temperature of Al@AP in the Microcanonical Ensemble (NVE) system stabilized at 2370 K, which is significantly higher than 1400 K observed for Al/AP, indicating enhanced ignition and combustion performance.