Hiroto Habu

Thermal behavior of new oxidizer ammonium dinitramide

Ammonium dinitramide (ADN) is a promising new oxidizer for solid propellants because of its high oxygen balance and high energy content, and halogen-free combustion products. One of the characteristics needed for solid propellants is stability. Heat, light, and moisture are factors affecting stability during storage, manufacture, and use. For practical use of ADN as a solid propellant, clarification of the mechanism of decomposition by these factors is needed to be able to predict lifetime. This study focused on thermal decomposition of ADN. Exothermal behavior of ADN decomposition was measured by isothermal tests using high-sensitive calorimetry (TAM) and non-isothermal tests using differential scanning calorimetry (DSC). Based on these results, analysis of the decomposition kinetics was conducted. The activation energy determined by TAM tests was lower than that from DSC tests. Thus, the decomposition path in TAM tests was different from that in DSC tests. The amount of ADN decomposition predicted from TAM tests was closer to that found under real storage conditions than the amount of decomposition predicted from DSC tests. Non-isothermal tests may not be able to precisely predict the lifetime of materials with a decomposition mechanism that changes with temperature, such as ADN. The lifetime predicted from DSC results was much longer than that from TAM tests especially at low temperature. It is necessary to use isothermal tests to predict the long-term stability at low temperature.

Influences of aging on thermal decomposition mechanism of high performance oxidizer ammonium dinitramide

Ammonium dinitramide (ADN) is one of the several promising new solid propellant oxidizers. ADN is of interest because its oxygen balance and energy content are high, and it also halogen-free. One of the most important characteristics of a propellant oxidizer, however, is stability and ADN is known to degrade to ammonium nitrate (AN) during storage, which will affect its performance. This study focused on the effects of aging on the thermal decomposition mechanism of ADN. The thermal behaviors of ADN and ADN/AN mixtures were studied, as were the gases evolved during their decomposition, using differential scanning calorimetry (DSC), thermogravimetry–differential thermal analysis-infrared spectrometry (TG–DTA-IR), and thermogravimetry–differential thermal analysis-mass spectrometry (TG–DTA-MS). The results of these analyses demonstrated that the decomposition of ADN occurs via a series of distinct stages in the condensed phase. The gases evolved from ADN decomposition were N2O, NO2, N2, and H2O. In contrast, ADN mixed with AN (to simulate aging) did not exhibit the same initial reaction. We conclude that aging inhibits early stage, low temperature decomposition reactions of ADN. Two possible reasons were proposed, these being either a decrease in the acidity of the material due to the presence of AN, or inhibition of the acidic dissociation of dinitramic acid by NO3−.

Thermal decomposition characteristics of mixtures of ammonium dinitramide and copper(II) oxide

Ammonium dinitramide (ADN) is one of the most promising new solid oxidizers for rocket propellants, since its oxygen balance and energy content are relatively high, and it does not contain halogens. To gain a better understanding of the thermal decomposition mechanism of ADN, the thermal decomposition of ADN and copper(II) oxide (CuO) mixtures was investigated. The thermal behavior and activation energy associated with the decomposition of ADN/CuO mixtures were analyzed using sealed cell differential scanning calorimetry (SC-DSC). SC-DSC results showed that CuO affects the thermal characteristics of ADN and promotes its decomposition. Thermogravimetry–differential thermal analysis–evolved gas analysis was also performed, and in addition, the decomposition behavior was observed using hot stage microscopy. From the results, a thermal decomposition mechanism was proposed for ADN/CuO. In this mechanism, copper dinitramide Cu[N(NO2)2]2 is generated at the surface of the CuO almost simultaneously with the melting of the ADN. Next, a significant exothermic reaction occurs, associated with the decomposition of Cu[N(NO2)2]2, followed by decomposition of CuO via [Cu(NH3)2](NO3)2 and Cu(NO3)2.

Effect of polymer addition amount and type on thermal decomposition behavior of spray-dried particles comprising ammonium nitrate, potassium nitrate, and polymer

Certain properties of ammonium nitrate (AN), such as high hygroscopicity and the thermal transformation of the crystal structure accompanied by volume changes, pose problems for industrial applications of AN. To solve these problems, we previously prepared AN-based particles by spray-drying. The particles contained potassium nitrate (PN) as a phase stabilizer and a polymer (e.g., PVA, CMCs, and Latex) to produce a moisture-resistant material. Herein, we investigate the thermal decomposition of spray-dried AN/PN/polymer particles by differential scanning calorimetry and Thermogravimetry–Differential thermal analysis. Comparison of the thermal decomposition of AN/PN/polymer materials with different amounts and types of polymers suggested that thermal decomposition at lower temperatures resulted from the reaction of AN with the molten polymer or decomposition products derived from the polymer. Therefore, it can be concluded that the thermal stability of the AN/PN/polymer was exclusively determined by the thermal properties of the polymer components.

Experimental Study of an N2O/Ethanol Propulsion System

Nitrous Oxide (N2O) / ethanol propulsion system is distinguished as the liquid propulsion with non-toxic, user-friendly, and storable bipropellant. The current target of the present study is to build a quick-response and maneuverable main engine of a sounding-rocket like flying test bed which will be applied to the hypersonic air-breathing propulsion researches in the near future. The application to the spacecraft propulsion is also considered due to its compatibility in lowtemperature operation environment. Two series of static firing tests were performed with 700 N class gas generator models so far. Current test results showed that valuable design data were collected and operational procedure was verified. Potential of application of composite materials to the combustion chamber was also examined from the chamber wall heat flux data obtained and the result of firing test using a thick SFRP chamber. Nomenclature

Catalytic Decomposition of Ammonium Dinitramide (ADN) as High Energetic Material over CuO-based Catalysts

CuO supported on a La2O3-doped alumina catalyst was prepared and tested in the decomposition process of an ADN–water energetic propellant. The decomposition products were investigated via on-line analysis. Moreover, CuO/Al2O3–La2O3 shows better results of ADN decomposition in comparison with CuO/Al2O3. Both catalysts were characterized by physico-chemical techniques.

Mixing of solid propellant by peristaltic pump based on bowel peristalsis

In recent years, the demand for rocket launching has increased due to the development of space technology. However, using inexpensive rockets is not always possible. Although the cost of solid-propellant rockets is relatively reasonable, safely manufacturing a large amount of solid propellant is difficult, and the manufacturing process is disjointed. Therefore, safe and continues manufacturing of solid propellant is necessary. On the basis of the movements of the intestinal tract, we realized that the movements required for transport and mixing of solid propellants are possible to achieve without the application of a large force. By mimicking these intestinal movements, we can safely and continuously manufacture a large amount of solid propellant. We developed a peristaltic pump, based on bowel peristalsis, using straight-fiber-type artificial muscle, and in this study, we demonstrate the usefulness of this pump for transporting the highly viscous fluids and solid-liquid mixed fluid. We consider that the peristaltic pump can also be effectively used as a mixing device. In this paper, we show that mixing one highly viscous fluid with another is possible by measuring the luminance values. In the manufacturing process, we use glass beads with the same diameter as microparticles and a sodium polyacrylate aqueous solution resembling a high viscosity fluid or hydroxyl-terminated polybutadiene as the raw material in the solid propellant. We then measure the glass beads in the resulting solid-liquid mixed fluid.

Solid Propulsion Systems for Epsilon Launch Vehicle

A new small solid launcher named Epsilon is currently under development in JAXA. The Epsilon launch vehicle is normally three stage rocket system and can be added an optional liquid propulsion system to the third stage for the missions requiring precision orbit insertion. The SRB-A motor boosting the H-IIA vehicle and the H-IIB vehicle will be shared as the first stage motor. Upper-stage motors are inherited from the fifth M-V launch vehicle, from the viewpoints of development cost reduction, performance increase, and advanced technology succession. The solid motor side jet (SMSJ) system, which is used for the roll control during the first stage powered flight and the three-axis control after the SRB-A burnout, will be newly developed based on the technology of the SMSJ for the M-V vehicle. A maiden flight of the first Epsilon is scheduled in the summer of 2013. A successive concept of the advanced propulsion technologies for next-gen Epsilon are also described in the present paper. There are many technical challenges, such as new propellants and mass reduction of nozzle liner, to be tackled with for the next couple of year.

B/TI multilayer reactive igniter for micro solid rocket array thruster

In this study, reactive B/Ti multilayer igniters were investigated for the noncontact ignition of a micro solid rocket array thruster in vacuum. When current is supplied to the B/Ti multilayer igniter, the chemical reaction: 2B + Ti rarr TiB2 + 1320 cal/g occurs, and high temperature plasma is discharged to a distance of several millimeters or more. The B/Ti multilayer igniters with 3 sizes were fabricated, and tested in 6 configurations of solid propellant. Although one rocket with ignition charge was ignited successfully, the noncontact ignition of the solid propellant was not achieved.