Reactive multilayer films (RMFs) can be integrated into semiconducting electronic structures with the use of microelectromechanical systems (MEMS) technology and represent potential applications in the advancement of microscale energy-demanding systems. In this study, aluminum/molybdenum trioxide (Al/MoO)-based RMFs with different modulation periods were integrated on a semiconductor bridge (SCB) using a combination of an image reversal lift-off process and magnetron sputtering technology. This produced an energetic semiconductor bridge (ESCB)-chip initiator with controlled ignition performance. The effects of the Al/MoO RMFs with different modulation periods on ignition properties of the ESCB initiator were then systematically investigated in terms of flame duration, maximum flame area, and the reaction ratio of the RMFs. These microchip initiators achieved flame durations of 60-600 μs, maximum flame areas of 2.85-17.61 mm, and reaction ratios of ∼14-100% (discharged with 47 μF/30 V) by simply changing the modulation periods of the Al/MoO RMFs. This behavior was also consistent with a one-dimensional diffusion reaction model. The microchip initiator exhibited a high level of integration and proved to have tuned ignition performance, which can potentially be used in civilian and military applications.
Nanothermites are attracting much attention because of the high energy density, self-sustained exothermic reaction, and high combustion temperature. However, they suffer from sintering and incomplete combustion, leading to poor reactivity and low energy utilization efficiency. In order to enhance the energy output and combustion performance of nanothermites, ammonium perchlorate (AP) was introduced into the Al/CuO nanothermites. The nanothermites with varied content of AP were prepared by electrospray. The morphological characterization of the nanothermites confirms that the nanoparticles are homogeneously mixed without agglomeration. Heat release, specific impulse, and peak pressure of gaseous products exhibit remarkable enhancement with increasing AP content. Specifically, the nanothermites with 7.5 wt % AP produce specific impulse and heat energy of ∼2.7 and ∼1.4 times higher than those of Al/CuO-based nanothermites without AP. In addition, the ignition delay time of the nanothermites containing AP is not greatly increased, enabling fast response during practical applications. Thermal analysis implies that the thermite reaction between Al and CuO can be divided into two steps in the presence of AP: solid−solid phase and liquid−solid phase diffusion reaction. These results provide facile strategy to enhance the output performance of nanothermites, which may facilitate the practical propulsion and combustion applications of nanothermites.
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