To enable the practical implementation of electrical ignition systems for spacecraft thrusters using an energetic ionic liquid, understanding the relationship between the composition, propellant performance, and electrochemical properties is important. The objective of this study is to investigate the effect of composition on propellant properties (e.g., theoretical specific impulse, solid precipitation at-35 degrees C) and electrochemical properties (e.g., electrolysis onset potential and specific resistivity) in a binary mixture of ammonium dinitramide and 2-hydroxylethylhydrazinium nitrate (ADN/HEHN). The theoretical specific impulse for ADN/HEHN mixtures increased with increasing ADN content, reaching a maximum of 298 s at an ADN molar ratio of 62%. A freezing test at-35 degrees C revealed that no solid precipitation occurred at ADN molar ratios of 50% or lower. Linear sweep voltammetry measurements showed that the electrolysis onset potential for the anode was 1.5 +/- 0.3 V vs. Ag, whereas the electrolysis onset potential for the cathode was-1.0 V vs. Ag for pure HEHN and-0.4 V vs. Ag for compositions containing ADN. Electrochemical impedance spectroscopy measurements showed that the specific resistivity decreased with increasing ADN molar ratio, reaching approximately one-third of the value for pure HEHN (611 Omega cm) at an ADN molar ratio of 60% (195 S2 cm). Among the compositions without solid precipitation at-35 degrees C, the ADN/HEHN mixture with an ADN molar ratio of 50% exhibited the highest specific impulse and the lowest specific resistivity.
Hybrid rocket engines are rarely used in practice because they have low regression rates. Therefore, attempts to increase regression rates have included augmentation of solid fuels with additives having high heat of combustion. This study specifically evaluated the performance of solid fuels with additives and assessed the combustion completeness of those additives: specifically boron, Al, and Mg powders. Boron powder has high combustion heat but its particles have an oxide shell that requires large amounts of heat to ignite. Actually, Al has the second highest heat of combustion after boron, but it also has an oxide shell and presents inherent ignition difficulties. Therefore, we introduced of magnalium (Mg-Al), which has higher ignitability than that of Al alone. By virtue of this characteristic, Mg-Al powder was expected to be effective at increasing boron powder ignitability. Two-dimensional (2D) visualization experiments demonstrated that the additives increased the regression rate, but the metal powder addition to the fuel beyond a certain percentage decreased the regression rate. Combustion experiments using a hybrid rocket engine verified Mg and Al composition effects on the boron combustion completeness. Experimentally obtained results demonstrated that the characteristic velocity increased and that the fuel regression rate decreased under conditions with boron and Al only. Because Al was a finer powder than the Mg powder used for this experiment, the liquefied fuel viscosity was expected to be greatest when it contained boron and Al only.
Nitrocellulose (NC) is typically synthesized by nitrating cellulose from cotton linter using a mixed acid of H2SO4 and HNO3. Okara, a soybean-processing byproduct often disposed of as waste, contains approximately 40 wt% of insoluble dietary fiber rich in cellulose, making it a promising alternative raw material for NC. In this study, NC was synthesized from okara under different pretreatment and nitration conditions. Light yellow powder (okara NC) was obtained with a maximum crude yield of 18.0%. Elemental analysis and Fourier transform infrared spectroscopy revealed that the chemical structure of okara NC was comparable to that of the reference NC, with a nitrogen content of approximately 12%. When NaOH-pretreated okara was used as the raw material, the resulting product exhibited a structure that more closely resembled that of the reference NC. In this case, thermal analysis indicated a heat amount of 2.20 kJ g(-1) and a decomposition temperature of 143.6 degrees C. Hot water washing after nitration increased the decomposition temperature; however, it remained lower than that of the reference NC.
Miniaturization of exploding foil initiator (EFI) system with micron-sized bridge foil (similar to 200x200 mu m(2)) may provide substantial improvement on detonator reliability and safety as well as manufacturing cost by lowering all-fire operational voltage and relieving many constraints on system design and fireset components. This numerical modeling study presents thermomechanical modeling on plastic flyer acceleration after bridge foil burst by pulsed energy input and high-speed flyer impact detonation initiation of HNS-IV explosive charges in such microscale EFI systems and low-energy fireset circuit. The compensation of deviation from linear bridge vapor expansion is introduced and detonation initiation criteria is recalibrated based on firing test results with thin flyer thickness in present modeling. The computational results on flyer velocity is well validated against the firing test measurements of EFI system with copper bridge foil and polyimide flyer. The influences of bridge and flyer thicknesses on detonation threshold are thoroughly investigated and the combined range of bridge and flyer thicknesses could be suggested for optimal EFI design of micron-sized bridge foil in terms of minimization of threshold charging voltage.
Carbonates have been used as only pyrotechnic colorants with other oxidisers. But it was considered that the using carbonates which did not contained chloride, nitrogen oxides, and sulfur as oxidiser in pyrotechnics composition is one of the solution methods for reducing of toxic and harmful ingredients and smoke. Calcium carbonate (CaCO3), which produces an orange flame in fireworks and not typically used as the main component in pyrotechnic compositions, was tested to be used as oxidiser in combination with Ti in this study for developments of carbonates-based pyrotechnics composition. And the substitution of commercial CaCO3 powder with eggshell, with calcium carbonate as their major component, was tested for making effective use of a food waste product. The mixture between CaCO3 and Ti was ignited under argon atmosphere as traditional pyrotechnics composition. The reaction products of the mixture which were TiC and CaTiO3 were determined, and the equation of combustion reaction was summarised. The mixture exhibited continuous combustion and low sensitivity, demonstrating the potential to be used in pyrotechnics. The spark generation was found to be enhanced on substituting CaCO3 with eggshell powder.
