Elucidating the role of Cu3Mo2O9 copper molybdate in regulating copper-molybdenum metal oxide-based thermite systems: An in-depth investigation

Cu 3 Mo 2 O 9 enables milder thermite combustion with sustained heat output. • Cu-O-Mo bonds suppress early Mo vaporization and gas-phase mass transfer. • Complex oxide structure enables controllable thermite energy release. In this study, copper-rich molybdate Cu 3 Mo 2 O 9 was synthesized via a hydrothermal-annealing route and employed as a foundational oxidizer to construct Al/Cu 3 Mo 2 O 9 composite thermites. A systematic comparative investigation was conducted against Al/(CuO + MoO 3 ) hybrid thermites regarding morphological characteristics, structural properties, combustion behavior, pressure output, thermal release profiles, and reaction pathways. The results demonstrate that the unique three-dimensional framework structure of Cu 3 Mo 2 O 9 effectively immobilizes molybdenum species through stable Cu-O-Mo bonds. This distinctive spatial configuration endows Al/Cu 3 Mo 2 O 9 with elevated activation energy, prolonged ignition delay, and reduced pressurization rates, manifesting a “mild combustion” characteristic with sustained and steady energy release. In contrast, Al/(CuO + MoO 3 ) exhibits violent deflagration behavior, significantly enhanced pressurization rates, and instantaneous heat concentration, attributable to the low-temperature sublimation of MoO 3 and multi-component selective reaction mechanisms. Analysis of pyrolysis and combustion products further confirms that divergent microscale mass transfer pathways constitute the primary origin of macroscopic energy release disparities between the two thermite systems. This study elucidates how complex metal oxide structures intrinsically regulate aluminothermic reaction kinetics and energy output, providing novel design strategies for high-performance, energy-tunable advanced thermite materials and broadening their prospects in thermal engineering applications.