Dielectric interface modification enables low-power microwave ignition of aluminum particles: Mechanisms and combustion performance evaluation

Microwave ignition technology holds transformative potential in multi-point simultaneous uniform ignition for propulsion systems and energy conversion, attributable to its non-intrusive energy delivery and rapid response characteristics, yet it faces challenges in igniting metallic fuels like aluminum (Al) particles inert to microwaves. To address this critical problem of microwave energy coupling inefficiency in Al, interfacial layers of PF (C 8 H 12 ClNO 2 and CF 3 (CF 2 ) 7 CH 2 CH 2 SH) and APTES (C 9 H 23 NO 3 Si) were constructed to introduce chemical bonding and electrostatic adsorption on the Al surface, followed by inducing CUFO (CuFe 2 O 4 ) dielectric interface anchoring and forming Al@PF@CUFO and Al@APTES@CUFO. This construction of core/shell not only shortens the mass and heat transfer distance but also enhances the interfacial polarization, leading to a strong response to microwaves. Microwave ignition analysis indicates that Al@APTES@CUFO (23.41 ms) exhibits a shorter ignition delay time compared to Al@PF@CUFO (29.51 ms), which can be attributed to the superior bridging capability and rapid decomposition of APTES. APTES not only shortens mass and heat transfer pathways but also facilitates rapid microwave energy absorption by Al/CUFO under microwave irradiation, generating localized hotspots and accelerating the ignition reaction kinetics. Furthermore, Al@PF@CUFO reveals a 327% increase in combustion rate compared to Al@APTES@CUFO, attributed to the fluorination reaction induced by PF decomposition and carbon catalysis derived from the decomposition of PDA. These findings establish dielectric interface engineering as a paradigm-shifting approach to overcome microwave ignition barriers in metallic fuels, with implications for next-generation microwave-controlled solid propellants, pyrotechnics, explosives, etc.