Traditional power supply systems based on batteries, as ineffective payloads, significantly hinder the development of ignition systems. To eliminate the dependence on batteries, we developed a self-powered ignition system utilizing a piezoelectric nanogenerator (PENG) based on ZnO-doped polyvinylidene fluoride (PVDF) nanofibers with high β-phase content. When subjected to external mechanical stimulation, the output voltage of the PENG reaches 32 V, which can charge a 22 μF capacitor to 15 V within 200 s and then simultaneously light up five LEDs. A self-powered ignition circuit composed of subsystems for power harvesting, storage, and discharge is assembled to activate igniters such as Ni-Cr wire, Ni-Cr film, standard semiconductor bridge (SCB), high-resistance SCB and small-sized SCB. The energy conversion processes of the igniters, whether via electric explosion or electrothermal manner, complete within 2 μs to 0.5 ms and then successfully ignite nanothermites of Al/CuO, primary explosives of lead styphnate, or mixtures of potassium chlorate and lead thiocyanate. Subsequently, a pressed B/KNO 3 (BPN) pellet, either in contact with or separate from the igniter by up to 3.3 mm, can be successfully ignited, fulfilling the ignition and transmission functions of ignition trains. These results demonstrate that the self-powered ignition system can work reliably without batteries, which is conducive to the miniaturization and intelligence of initiators and pyrotechnic devices.
In this study, the self-assembly method is used to modify Al nanoparticles (Al NPs) with perfluorotetradecanoic acid (PFTD) to obtain Al@PFTD. Based on the C–F…F–C interaction and the hydrogen bond between –CF and –CH, the adsorbed PFTD is used to direct the precipitation of P(VDF-HFP) around modified Al NPs to obtain Al@PFTD@P(VDF-HFP) composite energetic materials. Scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy are used to characterize the prepared samples, which prove a successful preparation process. The prepared Al@PFTD@P(VDF-HFP) is compared with physically mixed Al/P(VDF-HFP) counterparts by thermal analysis, electric ignition and constant-volume combustion tests. Thermal analysis results show that the reaction onset temperature of Al@PFTD@P(VDF-HFP) is 20 °C lower while its heat release is 135% higher. Electric ignition and constant-volume combustion tests show that the ignition delay, combustion time and pressurization rate are 50% shorter, 50% shorter and 40% faster, respectively. The improved energetic performance is mainly due to PFTD-directed precipitation of P(VDF-HFP) around Al NPs. Moreover, the fluorine-containing PFTD also contributes positively to energy density and reactivity through the pre-ignition reaction.
Chuntian Li,Hanwen Zhang,Zhidong Wang,Lian Li,Ruiqi Shen,Luigi T. De Luca,Wei Zhang
Hydroxylamine nitrate-based gel propellant (HAN-GP) materials have received attention due to their special electro-ignition properties, repeatable ignition characteristics, and green, pollution-free advantages. However, as a gel material, HAN-GP has higher conductivity than solid materials, which leads to reduced heat accumulation and may act as a conductor, thereby extending the ignition delay time and greatly limiting its application as a fuel for microthrusters. In this study, a copper-catalyzed HAN-GP was reported, which advances the decomposition temperature of the propellant and increases the heat transfer rate during the propellant's electrolytic process, thereby shortening ignition delay and achieving efficient combustion. By adding 0.2% copper powder, the decomposition temperature of the modified propellant is 77 °C lower than that of the baseline. At room temperature (30 °C), HAN-GP containing 0.2% copper powder (sample 3) increased the thermal diffusivity from 0.12 to 0.55 mm2 s−1 and the thermal conductivity from 0.08 to 0.16 W m−1 K−1, significantly enhancing its thermal conduction performance and heat transfer efficiency. Due to early thermal decomposition and rapid heat conduction effects, the ignition delay of sample 3 (300 ms) was reduced by 64% compared to the baseline (839 ms) at 225 V and 8 mL min−1. The total energy consumption of sample 3 decreased from 2500 J to 1800 J at 225 V and 4 mL min−1, which is a reduction of 28%. Additionally, it was found that its ignition energy could be further reduced to 30 J after multiple ignitions.
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