Trifunctional synergy of CuFe2O4 as oxidizer, catalyzer and microwave sensitizer in Ti-based pyrotechnics: Low ignition latency and superior combustion

Microwave ignition (MWI) technology enables synchronized large-area multi-point ignition, multi-pulse operation, higher combustion temperature and efficiency, and dynamic thrust modulation through microwave field adjustments compared to conventional electric ignition methods. However, MWI application is still limited by the absence of a microwave-responsive ignition agent. Herein, A series of nano-titanium/copper ferrite/potassium perchlorate ( n- Ti-CFO/KP (0∼40%)) microwave-sensitive agents were successfully synthesized via electrostatic spraying, where KP enhances combustion, while CFO acts as both catalyst and microwave sensitizer. MWI results demonstrate that n- Ti-CFO/KP (10%) exhibits the shortest ignition delay time (IDT) by 6.34 ms, owing to its high chemical reactivity and the high microwave absorption of Ti, CFO. Combustion analysis suggests that n- Ti-CFO/KP (40%) composite achieves 10-fold combustion enhancement over KP-free ignition agents by a peak pressure of 552.2 kPa and combustion rate of 221.4 m·s -1 , while n- Ti-CFO/KP exhibits the combustion flame temperature of 1250 °C compared to n- Ti-CFO by 700 °C. This remarkable improvement is attributed to the synergistic catalytic activation and combustion - supporting effects of CFO. Furthermore, n- Ti-CFO/KP (10%) exhibits comparable combustion and sensitivity performance to conventional agents ( μ- Ti/KP and B/KNO 3 ). The n- Ti-CFO/KP (10%) shows its main exothermic peak at 310 °C, significantly lower than the 550 °C peak observed for μ- Ti/KP, as well as the excellent catalytic decomposition effect of CFO on KP was further confirmed, where the low reaction temperature can shorten the microwave dielectric heating time. The synergistic effect and combustion intensification result from the coupled interaction between the microwave thermal characteristics of n- Ti-CFO and low-temperature oxygen release kinetics of KP. This coupling achieves significantly reduced MWI delay and enhanced energy release rates, thereby overcoming traditional combustion's reliance on high-temperature conditions. This result provides a new insight into the design of pyrotechnics and propulsion for fast plasma generation and microwave combustion.