Synergistic enhancement of oxalic acid-etched Al/I2O5@MoO3 thermite via surface pore engineering and oxidizer modulation

Oxalic acid etching creates porous surface on micron-Al particles. • Porous Al surface enlarges contact area with I 2 O 5 and MoO 3 oxidizers. • MoO 3 triggers low-temperature preheating and high-temperature Mo + I 2 exotherm. • Etched ternary thermite reduces activation energy by up to 106 kJ·mol −1 . • Ignition delay decreases 170 ms; flame temperature rises 749 °C. Micron-sized Al/I 2 O 5 thermite exhibits inferior ignition performance and low combustion efficiency due to the dense Al 2 O 3 passivation layer, which restricts the interfacial contact between Al and the oxidizer. Herein, a synergistic dual strategy combining oxalic acid surface etching (0.3 mol·L −1 ) of micron Al powder and MoO 3 incorporation is proposed to fabricate Al/I 2 O 5 @MoO 3 ternary thermite. Acid etching constructs uniform porous surface structures and substantially enlarges the Al-oxidizer contact area while maintaining a high active Al content. The introduced MoO 3 triggers a low-temperature exothermic reaction with Al at ∼380 °C, which preheats the thermite system and facilitates subsequent I 2 O 5 decomposition, as well as the high-temperature Mo-I 2 reaction at ∼1000 °C. Benefiting from the synergistic effects, the optimized thermite achieves a maximum activation energy reduction of 106 kJ·mol −1 , an ignition delay time reduction of up to 170 ms, and a flame temperature increase of 749 °C. The optimal MoO 3 mass fraction in the oxidizer is determined to be 0.1–0.2, while excessive MoO 3 induces combustion instability. This work provides mechanistic insights and practical guidelines for the design of high-performance Al/I 2 O 5 -based thermites via synergistic surface engineering and oxidizer modulation. Download: Download high-res image (171KB) Download: Download full-size image