Oxidizer In Solid Propellants Research Articles

The potentials of copper chromite nanoparticles on ammonium nitrate decomposition: Towards eco-friendly oxidizers for green solid propellants

Abstract Ammonium perchlorate (AP) is the universal oxidizer for solid propellants; AP combustion is accompanied with the release of white smoke (HCl). HCl has raised an environmental concern; it could cause acidic rain and deteriorate the fertile soil. Chlorine free and eco-friendly oxidizers are highly appreciated for green solid propellants. Ammonium nitrate (AN) could be the greener substitute for AP; yet AN expose low performance. Whereas AP demonstrated exothermic decomposition with the release of -733 J/g; AN demonstrated strong endothermic decomposition process of +1707 J/g. AN with strong endothermic decomposition process could render high burning rates. Copper chromite Nano catalyst of 45 nm was developed via hydrothermal synthesis. Copper chromite was integrated into AN matrix. Catalyzed AN demonstrated advanced exothermic decomposition enthalpy of -1492 J/g. Catalysed AN experienced diminish in activation energy by - 41.5 %, and – 40.6 % using Kissinger and Ozawa models respectively. Copper chromite NPs could secure novel catalytic effect via condensed phase reactions of chromium, and copper ions with nitrate ions (NO-3) to develop NOx gases. This catalytic effect can secure alternative pathway with low energy barrier. Consequently, catalysed AN can expose novel characteristics as a green eco-friendly oxidizer.

Customized Green Energetic Tetra(Imidazole)Copper(II) Nitrate (Cu-Im) Complex/Ammonium Nitrate Co-crystal: A Novel Reactive Halogen-Free Oxidizer with Superior Stability and Decomposition Kinetics

AbstractAmmonium nitrate (AN) is the most promising affordable green oxidizer for solid propellants; however, its endothermic phase transitions and endothermic decomposition restrict its applications. This work shaded the light on multifunctional energetic complex tetra(imidazole)copper (II) nitrate (Cu-Im) with combustion enthalpy of 15.57 KJ/g as a high energy dense material, phase stabilizer, and catalyst for AN-based propellant. The Cu-Im complex was synthesized via a green simple solvent-free melt-assisting technique. As-synthesized Cu-Im complex demonstrated a highly pure crystalline structure with thermal stability up to 200 °C. Cu-Im complex was integrated into AN via an evaporative crystallization technique. The phase transitions and the thermal behavior of the developed Cu-Im complex/AN cocrystal were investigated via DSC and TGA. The Cu-Im complex stabilized the phase transition of AN up to 88.48 °C via an evolved strong hydrogen bonding system within the Cu-Im complex/AN cocrystal. Moreover, the energetic Cu-Im complex offered a significant decrease in the endothermic phase transition peaks associated with IV↔II, and II↔I by 38.81%, and 25.28% respectively. Additionally, AN strong endothermic melting was decreased by 45.32%. The Cu-Im complex converts the AN endothermic thermal decomposition peak with + 1400 J/g into an intensive exothermic peak with the release of -2241 J/g. The Cu-Im complex exhibited a superior catalytic effect via the decrease in AN decomposition temperature by 48.85 °C. Cu-Im complex offered a remarkable reduction in apparent activation energy of AN decomposition by 56.24% and 48.12% via Kissinger’s model and integral iso-conversional nonlinear Vyazovkin method (VYA) respectively. The superior catalytic performance of the Cu-Im complex was attributed to the evolution of CuO nanoparticles during its decomposition. The electron-deficient Lewis acid copper ions have a large affinity to electron lone pair of nitrogen; this effect could support the conversion of NH3 to N2 and H2. This catalytic action could boost the decomposition enthalpy of AN. Consequently, the developed Cu-Im/AN cocrystal could be considered a potential green substitute for perchlorate-based oxidizers.

Preparation of Polydopamine Functionalized HNIW Crystals and Application in Solid Propellants.

The application of hexanitrohexaazaisowurtzitane (HNIW) as an oxidizer in solid propellants aligns with the pursuit of high-energy materials. However, the phase transformation behavior and high impact sensitivity of HNIW are its limitations. Due to the strong adhesion and mild synthesis conditions, polydopamine (PDA) has been employed to modify HNIW. However, the method suffers from a slow coating process and a non-ideal coating effect under short reaction time. Herein, oxygen-accelerated dopamine in situ polymerization coating method was developed. It was found that oxygen not only reduced the coating time but also contributed to forming a dense and uniform PDA layer. HNIW@PDA coated in oxygen for 6 h exhibited the most favorable performance, with a delay of 20.8 °C in the phase transition temperature and a reduction of 145.45% in the impact sensitivity. The -OH groups on the surface of PDA enhanced the interaction between HNIW and polymer binders, resulting in a 20.36% reduction in the dewetting percentage. The lower content of PDA in HNIW@PDA (1.17%) resulted in minimal variation in the heat of explosion for HNIW@PDA-based HTPB propellant (6287 kJ/kg) in comparison to HNIW-based HTPB propellant (6297 kJ/kg). Hence, HNIW@PDA-based propellants are expected to offer an alternative with promising safety and mechanical performance compared to existing HNIW-based propellants, thus facilitating the application of HNIW in high-energy propellants. This work presents a low-cost method for efficiently inhibiting the phase transformation of polycrystalline explosives and reducing the impact sensitivity. It also offers a potential approach to enhance the interfacial interaction between nitro-containing explosives and polymer binders.

Synthesis of perforated single-crystalline Mn2O3 microcubes for thermocatalytic applications

Perforated mesoporous manganese(iii) oxide microcubes (PMOM) were synthesized via morphology-conserved transformation of precursor method and enhanced surface reactions catalyse the decomposition of ammonium perchlorate, a solid propellant oxidizer.

Regulating Chemistry Composition on a Crystal Surface by Introducing a Cation Trapping Agent: A Novel Strategy to Tune Moisture Sensitivity of Crystals.

The crystal moisture sensitivity can be tuned by the chemical composition on the crystal surface. Ammonium dinitramide (ADN) crystal is a promising oxidizer for solid propellants. However, its strong moisture sensitivity greatly limits its practical applications. Here, we report a novel strategy to reduce moisture sensitivity by trapping ammonium cations with montmorillonite (MMT) to modulate the chemistry composition on the ADN crystal surface. An extraordinary phenomenon can be found: the crystal surface of the recrystallized ADN with 1% MMT (ADN-1% MMT) is rearranged with more low-surface-energy -NO2 groups (65.84%) and less high-surface-energy NH4+ groups (4.8%). In addition, ADN-1% MMT presents a more homogeneous low surface energy feature with a narrower surface energy distribution. As a result, ADN-1% MMT exhibits a noticeably lower hygroscopicity at 20 °C and 60% RH, which is accordant with the simulated hygroscopicity based on XRD and moisture sensitivity prediction based on surface energy. This study brings out a novel modification idea to adjust crystal moisture sensitivity by tuning the chemistry composition on the crystal surface based on trapping cations.

Insight into the Thermodynamic Properties of Promising Energetic HNTO·AN Co-Crystal: Heat Capacity, Combustion Energy, and Formation Enthalpy

A novel energetic co-crystal composed of hydrazinium 3-nitro-1,2,4-triazol-5-one (HNTO) and ammonium nitrate (AN), as a composite solid propellant oxidizer, was recently developed to substitute either pure ammonium perchlorate (AP) or nitrate. Unfortunately, the thermodynamic properties of this co-crystal or even the pure HNTO are not available in the open literature. Therefore, in this work, the low-temperature heat capacities of HNTO and HNTO·AN co-crystal were measured in the temperature range from 213.15 K to 378.15 K using differential scanning calorimetry. By fitting the heat capacity data, the thermodynamic functions ΔH298.15K, ΔG298.15K, and ΔS298.15K were derived. In addition, the standard molar energies of combustion ΔcU° of HNTO and HNTO·AN co-crystal were determined, and from the combustion results, the standard molar enthalpies of combustion ΔcHmo and formation ΔfHmo of these energetic compounds were derived at T = 298.15 K. The set of thermochemical data has been proposed in this work for the first time and will be undoubtedly indispensable information for the development of energetic materials based on HNTO and HNTO·AN co-crystal.

A SHORT REVIEW: THE EFFECT OF NANOMATERIALS FOR THERMAL DECOMPOSITION OF SOLID PROPELLANT OXIDIZER AP

This review attempts to discuss data related to the work of kinds of literature on various nanomaterials such as ferrites, oxides, and chromates of transition metals which lead to gain prominent attention in the field of thermal decomposition of solid propellant oxidizer mainly ammonium perchlorate (AP). The effect of catalysts like metal oxides, inorganic and organic compounds, etc., is discussed for the thermal decomposition of ammonium perchlorate (AP). This study underscores the experimental effectiveness of these catalysts in the decomposition process of solid propellants which enhances fast decomposition through decreasing their exothermic peak temperature. Such kind of improvements in propellant oxidizer and binder fuel help to increase the efficiency of rocket missiles.
 GRAPHICAL ABSTRACT
 This short review includes the discussion on thermolysis of propellant oxidizers and their composite solid propellants from the few prime lists of literature. This aims to understand the behavior of nanomaterials as a catalyst for the thermal decomposition of propellant oxidizer ammonium perchlorate. Ammonium perchlorate has a polyhedron-like shape that undergoes decomposition upon heating from room temperature to ~420 ℃ with gaseous by-products. In the presence of catalyst, the decomposition occurred at a lower temperature than the pure ammonium perchlorate. Thus, it can be used in the formulation of propulsion systems that mainly improve their burn rate ultimately helpful in rocketry.

MWNTs Coated with CuO Particles: A Novel Nano-catalyst for Solid Propellants

MWNTs can expose surface area (> 700 m2 g−1) as well as high catalyzing ability; additionally they can act as carrier for energetic components. This study reports on coating MWNTs with copper particles throughout electroless plating. Hybrid Cu-MWNTs was annealed at 250 °C to develop CuO-MWNTs. TEM micrographs demonstrated MWNTs regularly coated with CuO nanoparticles. XRD diffractograms revealed high crystalline structure. Ammonium perchlorates (APC) is common oxidizer for solid propellants; however its decomposition is an endothermic process. Synthesized CuO-MWNTs were encapsulated into APC oxidizer via solvent–antisolvent technique. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were employed to investigate catalytic performance of CuO-MWNTs. At 1 wt%, CuO-MWNTs decreased APC endothermic decomposition by 16.3%. The two subsequent exothermic decomposition stages were fused into one stage with surge in total heat release by 100%. These novel features can inherit CuO-MWNTs exclusive catalyzing ability.

Properties and Structure of ADN‐Prills

AbstractAmmonium dinitramide (ADN) is the upcoming oxidizer for solid propellants of the current decade. Spherical ADN particles, so‐called ADN‐prills, are a key product for the development of environmentally friendly and low‐signature solid propellants for defence and space applications. At the moment the particle size and the spherical shape of the ADN‐prills can be controlled by the emulsion crystallization process or by spray congealing processes. In this work the crystal structure and the thermal‐ and mechanical stability of ADN‐prills were investigated. By temperature resolved X‐ray diffraction measurements new insights about temperature depending crystalline structures inside of ADN‐prills could be gained. Anisotropic crystal properties could be detected at certain temperature ranges between ambient temperature and the melting point of ADN at 93 °C. Due to the unexpected material properties of molten ADN droplets a surprising correlation between process parameters, particle size, crystal structure, thermal stability and mechanical stability was found. This leads to a more profound knowledge about the crystal structure of ADN‐prills and gives the opportunity to produce enhanced ADN particles for propellant applications.

Introducing Novel Tetrazole Derivatives as High Performance Energetic Compounds for Confined Explosion and as Oxidizer in Solid Propellants

AbstractThis paper introduces five novel high‐nitrogen content (N>50%) tetrazole derivatives with desirable physicothermal properties, high detonation and combustion performance as well as suitable sensitivities with respect to external stimuli electric spark and heat. Suitable density functional theory (DFT) and empirical methods were used to predict their crystal density, melting point, condensed phase heat of formation, enthalpy of fusion, Gibbs free energy of formation, velocity of detonation, detonation pressure, Gurney velocity, heat of detonation, power (strength), brisance, impact sensitivity, electric spark sensitivity, heat sensitivity and specific impulse. Two compounds 5,5′‐[(1Z,5Z)‐3,4‐dinitrohexaaza‐1,5‐diene‐1,6‐diyl]bis(1‐nitro‐1H‐tetrazole) and 3,3′,7,7′‐tetranitro‐3,3a,3′,3′a‐tetrahydro‐7H,7′H‐6,6′‐bitetrazolo[1,5‐e]pentazine as compared to the other new derivatives can be introduced as high performance explosives for confined explosion and oxidizers in solid propellants.

The effect of cellulose derivatives on the phase transition and thermal behavior of ammonium nitrate

Ammonium nitrate (AN) is a cheap oxidizer, which is widely used in chemical industries, fertilizers, industrial explosives, military explosives and propellants. It shows low reactivity, high hygroscopicity and polymorphic phase transitions in ambience condition where these behaviors can limit its application as an oxidizer in solid propellants. Since AN provides low decomposition temperature, maximum gas per unit weigh and non-toxic products, it is usually used as an oxidizer in gas generators. In this work, the effect of cellulose derivatives on the phase transition and thermal behavior of AN has been investigated in order to extend its uses in smokeless and environmentally safe solid gas generators. Thermal behaviors of AN/cellulose derivative matrixes, AN/KNO3 and AN/KF have been studied by the simultaneous application of thermogravimetry (TG) and differential scanning calorimetry. Moreover, a suitable computer code has been used to study the theoretical exhaust gases and mass of solid residues. The results suggest that cellulose acetate can be introduced as a good candidate for removing inappropriate phase transitions of AN.

EFFECT OF CU-CO MIXED METAL OXIDES ON THE COMBUSTION OF PSAN-HTPB BASED SOLID PROPELLANTS

Composite propellants based on ammonium perchlorate (AP) as oxidizer are state-of-the-art. However, global environmental impact restricts AP-based propellants because of their high chlorine exhaust. Therefore, efforts are on to innovate propellants with clean exhaust. Ammonium nitrate (AN) has, thus, regained importance in the field of propellants and explosives, more specifically in insensitive formulations, because of its clean burning and low hazard. However, the stumbling block for the application of AN - as solid propellant oxidizer has been its dimensional instability caused by phase transformation which results in increase of volume and porosity of the propellant grain. This can be overcome by the use of phase stabilized ammonium nitrate (PSAN). In the present study AN phase stabilized by incorporating 10% KN to prepare composite solid propellant. Copper-Cobalt mixed metal oxides have been synthesized via citric acid complexing method. Three different catalysts were prepared with different Cu-Co molar ratios 1, 0.5 And 2 in the initial reactants. The synthesized catalysts were then added to the PSANHTPB(Phase Stabilized Ammonium Nitrate- Hydroxyl Terminated Poly-Butadiene) composite formulations. These propellant samples were subjected to burn rate measurement in a Crawford High Pressure Strand Burner and thermal degradation studies in Simultaneous Thermal Analyzer (STA). The thermal decomposition and burn rate of the propellant is observed maximum on the addition of Copper-Cobalt mixed metal oxide catalyst with molar ratio 2. A total of six propellant samples catalyzed and noncatalyzed and one preheated virgin sample were undertaken for the above analysis and results obtained are discussed. It has been observed that except the propellant sample with Cu-Co-III and virgin propellant where PSAN was prepared by solid mixing, other propellant samples were hard to burn.

Trilite adsorption characteristics for perchlorate from Korean military facilities

Perchlorate is used as an oxidizer in solid propellants for rockets, missiles, and fireworks. It is not classified as a carcinogen according to the US EPA, EU, and WHO; however, it affects the respiratory system and skin. Perchlorate removal is not very effectively achieved by biological processes with coagulation and activated carbon. At present, relatively efficient removal methods, which have been tested and backed by study, include ion exchange and membrane processes. Ion exchange is the most commonly used method, and it has proven to be the most effective. The maximum perchlorate concentrations in Korea and USA were 107.7 μg/L and 2600 mg/L, respectively, exceeded the Drinking Water Equivalent Level (DWEL) by the US EPA (24.5 μg/L). The perchlorate removal method was tested using an isothermal adsorption experiment that determined the characteristics of perchlorate adsorption onto Trilite. Evaluation of these results suggests a potential for local application of Trilite for perchlorate removal. The parameters and coefficients for adsorption isotherms were determined with linear and non-linear regression methods. The coefficient of determination of the Langmuir-1 isotherm was the highest (R2 = 0.998), and the maximum adsorption was 145 mg/ml, which was higher than reported for other anion exchange resins. The non-linear regression analysis showed the highest coefficient of determination (R2 = 0.968) for both the Langmuir and Redlich-Peterson isotherms. The optimal adsorption isotherms with the non-linear regression method were the Langmuir and Redlich-Peterson isotherms. The potential for local application of Trilite was evaluated via the Langmuir isotherm, which has a relatively simple formula. The value of R s was 0.028 (between 0< R s ≪1) or “very favorable.” Therefore, Trilite appeared to be among the desirable alternatives for the effective removal of perchlorate.

Effects of temperature on nitration of sulfamates

Ammonium dinitramide (ADN) has attracted great interest as a potential oxidizer for next generation rocket propellants. It is a halogen-free alternative to ammonium perchlorate, which is currently in wide used as a solid propellant oxidizer. However, in ADN synthesis, N-nitration is necessary to form the N-(NO2)2 group. Using a reaction calorimeter, the thermal behavior of nitration of sulfamates (K, Na, and NH4) using a mixture of acids (HNO3/H2SO4 and HNO3/AcOH) as the nitration agent was examined. The heat of decomposition of potassium sulfamate at −10 °C was greater than that at 20 °C. The heat of decomposition decreased in the following order: K salt>Na salt>NH4 salt in HNO3/H2SO4. The dipole moments of the sulfamates were calculated, and the results revealed that the electronic states of nitrogen were different. Thus, the dipole moments of sulfamates affect the decomposition heat of sulfamates. The heat of decomposition in HNO3/AcOH was larger than that in HNO3/H2SO4.

Thermal decomposition of the high-performance oxidizer ammonium dinitramide under pressure

Ammonium dinitramide (ADN) is a promising new oxidizer for solid propellants because it possesses both high oxygen balance and high energy content, and does not contain halogen atoms. A necessary characteristic of solid propellants is chemical stability under various conditions. This study focused on the thermal decomposition mechanism of ADN under pressurized conditions. The pressure was adjusted from 0.1 to 6 MPa, while ADN was heated at a constant rate. The exothermal behavior and the decomposition products in the condensed phase during heating were measured simultaneously using pressure differential scanning calorimetry (PDSC) and Raman spectrometry. PDSC analyses showed the multiple stages of exotherms after melting. The exothermal behavior at low temperatures varied with pressure. Analysis of the decomposition products indicated that ammonium nitrate (AN) was generated during decomposition of ADN at all pressures. At normal pressure, AN was produced at the same time as start of exotherm. However, the temperature at which the ratio of ADN in chemical species in the condensed phase began to decrease under high pressure was higher than that at atmospheric pressure despite the existence of significant exotherm. At initial stage, thermal decomposition of ADN that does not generate AN was thought to be promoted by increased pressure.

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.

Use of potassium ferrocyanide as habit modifier in the size reduction and phase modification of ammonium nitrate crystals in slurries

Ammonium nitrate (AN) is an inorganic crystalline compound used as a solid propellant oxidizer and as a nitrogenous fertilizer. The practical use of AN as solid propellant oxidizer is restricted due to the near room temperature polymorphic phase transition and hygroscopicity. A good deal of effort has been expended for last many years to stabilize the polymorphic transitions of AN, so as to minimize the storage difficulties of AN based fertilizers and to achieve more environmentally benign propellant systems. Also, particles with aspect ratio nearer to one are a vital requirement in fertilizer and propellant industries. In the present study AN is crystallized in presence of trace amount of potassium ferrocyanide (K 4Fe(CN) 6) crystal habit modifier and kept for different time intervals. And the effect of K 4Fe(CN) 6 on the habit and phase modification of AN was studied. Phase modified ammonium nitrate (PMAN) with a particle aspect ratio nearer to one was obtained by this method and the reasons for this modifications are discussed. The morphology changes were studied by SEM, the phase modifications were studied by DSC and the structural properties were studied by powder XRD.

Role of Poly(vinyl alcohol) in the Crystal Growth of Ammonium Perchlorate

One of the key aspects in the development of new inorganic materials is the synthesis of particles with specific sizes and morphologies. Nowadays, water-soluble polymers as crystal-growth modifiers are gaining more importance in the field of morphogenesis of inorganic crystals. Ammonium perchlorate (AP) is an extensively used solid propellant oxidizer. Oxidizer particles with a particular morphology are a challenging requirement in the propellant field. In the present study, AP with different morphologies was synthesized by the polymer-assisted crystal-habit modification route. Poly(vinyl alcohol) and AP salt solutions were prepared and mixed in different proportions. Samples were drawn from the mixture, dried on glass slides, and analyzed by scanning electron microscopy and powder X-ray diffraction (PXRD). AP crystals with a rectangular prism and a rectangular wedge shape were obtained, and the reasons for their shapes are discussed. The PXRD patterns showed that the phase of AP obtained is the same as t...

Ammonium nitrate: a promising rocket propellant oxidizer

Ammonium nitrate (AN) is extensively used in the area of fertilizers and explosives. It is present as the major component in most industrial explosives. Its use as an oxidizer in the area of propellants, however, is not as extensive as in explosive compositions or gas generators. With the growing demand for environmental friendly chlorine free propellants, many attempts have been made of late to investigate oxidizers producing innocuous combustion products. AN, unlike the widely used ammonium perchlorate, produces completely ecofriendly smokeless products. Besides, it is one of the cheapest and easily available compounds. However, its use in large rocket motors is restricted due to some of its adverse characteristics like hygroscopicity, near room temperature phase transformation involving a volume change, and low burning rate (BR) and energetics. The review is an attempt to consolidate the information available on the various issues pertaining to its use as a solid propellant oxidizer. Detailed discussions on the aspects relating to phase modifications, decomposition chemistry, and BR and energetics of AN-based propellants, are presented. To make the review more comprehensive brief descriptions of the history, manufacture, safety, physical and chemical properties and various other applications of the salt are also included.

ADN: A new high performance oxidizer for solid propellants

ADN: A new high performance oxidizer for solid propellants