Metal-organic frames (MOFs) effects on the microwave ignition of ADN-based liquid propellant

Ammonium dinitramide (ADN) liquid propellants are mostly used in catalytic ignition, but catalyst deactivation is a common issue during the heating process. Microwave is used as the energy source to ignite ADN, so as to avoid the technical bottleneck of traditional catalytic ignition of ADN. However, pure ADN solution fails to ignite under microwave radiation. Metal-organic frameworks (MOFs) can significantly enhance the absorption of electromagnetic energy owing to their superior electromagnetic absorption capabilities. In this work, we introduce a methodology for igniting and combusting ADN through the incorporation of MOFs, which serve as hotspots and absorbent materials under microwave irradiation. The ignition conditions of ADN with magnetic and non-magnetic MOFs under microwave radiation were systematically compared and analyzed. In comparison to pure ADN solutions, MOFs’ exceptional wave absorption performance augments the sample’s capacity to absorb and convert electromagnetic energy per unit time. By adjusting the ratio between ADN and MOFs, the maximum microwave absorption effect is achieved. Ignition experiments demonstrate that the incorporation of MOFs facilitates successful ignition of ADN under microwave radiation. Microwave ignition of ADN was achieved at MOF 5.0 wt%, with delay times inversely proportional to input power. The optimal 7.5 wt% MOF composition demonstrated prefer ignition efficiency in the ADN/MOF system. Despite variations in MOFs types, ADN/MOFs composites exhibit identical ignition and combustion phenomena under microwave radiation. In summary, this study establishes a foundation for microwave radiation-induced ignition of ADN with MOFs and enhances the efficiency of microwave energy utilization.