Enhancing the interfacial kinetics and energetic performance of micro-Al-based thermites through glycolic acid-induced surface engineering

Defect−rich Al powder was prepared via eco−friendly glycolic acid etching. • Combustion mechanism shifted from melt-dispersion to defect-mediated diffusion. • Apparent activation energy of Al/CuO system was reduced by 25.2%. • Enhanced interfacial affinity boosted combustion dynamics with shorter ignition delay and higher peak pressure. To overcome the inherent limitations of micron-sized aluminum (μm-Al) in energetic applications, that is, prolonged ignition delay and incomplete combustion, this study proposes an eco-friendly surface engineering strategy via controlled glycolic acid etching. The deliberate acidification of 10 μm-Al yields a sub-micron pit architecture that simultaneously enhances the reactive surface area and active Al content. When integrated into Al/n-CuO thermites, the optimized etched Al (8-hour etching) demonstrated superior reactivity. Kinetic analysis revealed a 25.25% reduction in activation energy (from 479.08 kJ·mol −1 to 358.12 kJ·mol −1 ) compared to the raw Al system. More importantly, constant-volume combustion tests showed that the etched Al thermite exhibited a peak pressure of 342.02 kPa and a violent pressurization rate of 5.86 MPa·s −1 , which are 1.4 and 3.2 times those of the raw Al counterpart, respectively. These enhancements, coupled with a 53.67% increase in combustion temperature and a 27.8% reduction in ignition delay, are attributed to the alleviated interfacial mass transfer barriers provided by the pit structure. This strategy offers an eco-friendly pathway to tailor the combustion kinetics of metallic fuels for advanced energetic composites. Download: Download high-res image (228KB) Download: Download full-size image