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About this book

This book focuses on the combustion performance and application of innovative energetic materials for solid and hybrid space rocket propulsion. It provides a comprehensive overview of advanced technologies in the field of innovative energetic materials and combustion performance, introduces methods of modeling and diagnosing the aggregation/agglomeration of active energetic metal materials in solid propellants, and investigates the potential applications of innovative energetic materials in solid and hybrid propulsion. In addition, it also provides step-by-step solutions for sample problems to help readers gain a good understanding of combustion performance and potential applications of innovative energetic materials in space propulsion. This book serves as an excellent resource for researchers and engineers in the field of propellants, explosives, and pyrotechnics.

Table of Contents

Frontmatter

Properties of Innovative Energetic Materials

Frontmatter

Chapter 1. Study of a Concept of Energetic Materials Consisting of a Solid Fuel Matrix Containing Liquid Oxidizer

Abstract
Composite energetic materials such as solid propellants are characterized by a solid fuel, typically a polymeric binder matrix, containing solid oxidizer particles. The energetic performance of solid propellants is inferior to that of liquid or hybrid propellants. The main reason is that the available practical solid oxidizers are less energetic than the available liquid oxidizers. This article presents and studies the novel concept of an energetic material consisting of a solid fuel matrix containing liquid oxidizer units. The oxidizer units may be capsules filled with a liquid oxidizer. The size of the capsules may be similar to that of typical solid oxidizer particles. In this way, one maintains the structural characteristics of a solid material (e.g., solid propellant), yet benefiting from the superior energy of a liquid oxidizer. The study reveals the theoretical energetic performance (specific impulse) of solid propellants containing different liquid oxidizers compared to standard solid propellants consisting of ammonium perchlorate (AP) oxidizer. It is shown that the combination of certain liquid oxidizers such as hydrogen peroxide or nitrogen tetroxide with a hydroxyl-terminated polybutadiene (HTPB) matrix can increase the overall energy by about 20%, implying about 12% increase in the specific impulse. The combustion processes are discussed as well.
Avishag Deborah Pelosi, Alon Gany

Chapter 2. Enhancing Micrometric Aluminum Reactivity by Mechanical Activation

Abstract
The pursuit of solid rocket motor and hybrid rocket engine performance enhancements is pushing toward the research of novel energetic materials replacing the conventional micron-sized aluminum. Nanotechnology opened the way to new concepts, introducing very promising ingredients like nano-sized aluminum powders. Their effectiveness in increasing energetic system performance has been already proven at lab-scale level. However, the high cost, the dispersion difficulties, and the increased handling risk hinder a widespread application of nanomaterials. On the other hand, activation techniques offer the possibility of micron-sized additives reactivity enhancement while maintaining high safety levels and reduced costs. This work deals with the design, the production, and the characterization of mechanically activated ingredients for solid propellants and hybrid rocket fuels. General guidelines for the powder processing implementation are critically discussed. Additives are characterized in the pre-burning phase, and their effects on the ballistic response of solid propellants and hybrid fuels are investigated. Activated powders improved hybrid fuel regression rate and reduced the size of the condensed combustion products of solid propellants, confirming their suitability for the micron-sized aluminum replacement.
Stefano Dossi, Christian Paravan, Filippo Maggi, Luciano Galfetti

Chapter 3. Preparation and Energetic Properties of Nanothermites Based on Core–Shell Structure

Abstract
Nanothermites refer to the mixtures of metal fuels and oxidizers, at least one component of which is nanoscale. In the past few decades, nanothermites have attracted much attention as a kind of highly reactive nanoenergetic materials (nEMs). Since nanothermites are mixtures rather than single compounds, the mass-transport efficiency between the reactants dominates their reaction kinetics, thus many efforts have been made to increase the number of contact sites between fuels and oxidizers. Building core–shell structured nanothermites is an effective way to overcome the uneven distribution of fuels and oxidizers and increase the contact area between the reactants. According to the construction sequence of fuel and oxidizer, the core–shell nanothermite can be divided into two main categories, including fuel–oxidizer and oxidizer–fuel. Their exothermic properties, combustion, and pressure performance have been preciously controlled by adjusting composition, size, and structure. In this chapter, the preparation strategies and energetic properties of core–shell nanothermites are introduced and summarized. In particular, the advantages of core–shell structured nanothermites in terms of energy density and combustion efficiency are clarified, based on which suggestions regarding the possible future research directions are proposed.
Xiaoxia Ma, Kaili Zhang

Chapter 4. Current Problems in Energetic Materials Ignition Studies

Abstract
Several problems of ignition of energetic materials (EMs), which are able to burn in the absence of an external oxidizer, are discussed in this chapter. Scientific investigation of the EMs ignition has started at the end 1930th when the first field missiles (Katyusha) were developed in the USSR. Later the investigations were actively performed in USA and Europe but despite rather long history there still remain unsolved problems related to complete description of nonstationary transition to self-sustaining combustion, correct determination of the ignition moment, determination of the EM high-temperature reaction kinetics, etc. In the early studies, the limiting cases of the EM ignition solely due to exothermic reactions either in the condensed or gas phase were investigated but later it was revealed that for many EMs such reactions can proceed simultaneously in both phases. This implies the necessity of analyzing the ignition mechanisms involving reactions in the condensed as well as in the gas phase. In this chapter, the attention is paid to theoretical description of transient burning rate behavior of the EMs exothermically reacting in both phases, to the formulation of ignition criterion and to the experimental methods of measuring transient burning rate. In addition, the problems of correct determination of the EMs high-temperature kinetics are discussed as well as the problems of ignition of EMs with shielded reacting surface (opaque and semitransparent substances). Obviously, due to restricted volume, the chapter could not answer all questions but its content may become useful for researchers working in this field in order to better understand state of the art of EMs ignition studies and better plan some future researches in this direction.
V. E. Zarko, A. G. Knyazeva

Combustion Performance of Energetic Materials

Frontmatter

Chapter 5. Transient Burning of nAl-Loaded Solid Rocket Propellants

Abstract
The introduction of nano-sized energetic ingredients first occurred in Russia about 60 years ago and produced great expectations in the rocket propulsion community. While steady combustion regimes of solid rocket propellants loaded with nanometals are discussed in a companion paper, several instances of unsteady combustion regimes are examined in this paper. Ignition, extinction by fast depressurization, self-sustained oscillatory burning, pressure deflagration limit, and other transient burning processes are considered. Both steady and unsteady combustion papers describe the main features in terms of solid propellant performance and intend to emphasize the unique properties or operating conditions made possible by the addition of nano-sized energetic ingredients. Attention is mainly focused on nAl addition to AP/HTPB formulations, the workhorse of solid space launcher motors.
Luigi T. DeLuca, WeiQiang Pang

Chapter 6. Aluminized Solid Propellants Loaded with Metals and Metal Oxides: Characterization, Thermal Behavior, and Combustion

Abstract
In this chapter, the combustion behavior of multicomponent aluminized propellants loaded with different metals and metal oxides (in particular, B, Zn, Ni, Cu, Mo, Co3O4, V2O5, MnO2, Fe2O3, and CuO) are described. The correlation between properties of propellant composition and components and regularities of burning process are presented for formulations based on mixture of HMX, CL-20, and ammonium perchlorate. The burning law was defined experimentally by means of Vielle bomb over the pressure range 1–10 MPa, while some combustion properties were obtained theoretically. The effects of metal powder chemical and phase composition on burning law were considered as well as their oxidation reactivity, morphological, and the other properties. The most significant increasing of burning rate was observed for substances promoting catalytic propellant components decomposition with nearly constant thermodynamic properties. Thus, addition of metal and metal oxide could be effective way to adjust burning rate of propellants without affecting its ballistic properties.
Alexander A. Gromov, Konstantin V. Slusarsky, Alexey V. Sergienko, Elena M. Popenko, Ella L. Dzidziguri, Kirill B. Larionov, Ilya V. Mishakov

Chapter 7. Bimetal Fuels for Energetic Materials

Abstract
Metal powders (mainly aluminum), due to their high energy density, are important fuels for propulsion systems, material synthesis, and energetic materials. However, the use of aluminum is complicated by the fact that during storage and combustion on the surface of the particles an inert oxide layer is formed, which prevents the access of an oxidizer and increases the ignition and burning times of particles. Prospective solution to the problem of increasing the efficiency of metal fuel combustion is the complete or partial replacement of aluminum by energy-intensive components or Al/Mg alloys in energetic materials. This chapter presents the thermal analysis data, the ignition parameters, the combustion, and agglomeration characteristics for the propellants based on ammonium perchlorate, butadiene rubber, and Alex, Alex/Fe, Alex/B ultra-fine powders. The experimental results showed the reduction of the ignition delay time and increase of the burning rate for the EM sample containing Alex/Fe ultra-fine powder in comparison with the Al-based energetic material. The presence of amorphous boron in the bimetal fuel of EM significantly increases the agglomeration of condensed combustion products and practically maintains the burning rate of propellant unchanged.
Alexander G. Korotkikh, Oleg G. Glotov, Ivan V. Sorokin, Vladimir A. Arkhipov

Chapter 8. Combustion/Decomposition Behavior of HAN Under the Effects of Nanoporous Activated Carbon

Abstract
This work presents experimental results on thermal decomposition and combustion of hydroxylammonium nitrate (HAN)-based propellant (HAN—95 wt% water solution) in the presence of nanoporous activated carbon with a high specific surface area (SSA) up to 3000 m2/g. The activated carbon AC was obtained by primary carbonization of rice husk (RH) and subsequent activation of carbonized rice husk (CRH) with potassium hydroxide at the temperature of 700 °C in a rotating spherical furnace. Combustion of HAN in the presence of activated carbon (AC) was investigated in a constant-pressure bomb within the initial pressure range of 1–6 MPa. The linear burning rate (rb) increased for the system of HAN admixed with AC compared to those of the HAN alone. The rb of HAN with AC was equal to 400 mm s−1 at an initial pressure of 6 MPa. It was shown that nonporous AC is a good candidate as an additive for increasing the productivity (high burning rate, high gas exhaust, low initial pressure value for combustion propagation, and low commercial cost of the additive) of HAN-based propellants. Thermal decomposition of HAN-based propellant admixed with AC was assessed by DTA–TG method. Addition of AC reduces the temperature of the onset of HAN decomposition from 185 to 86 ± 0.5 °C. The obtained results allow to assume that addition of just 1% AC affects both the temperature of the onset of complete decomposition and maximum temperature of HAN decomposition. The increase in AC concentration up to 10% leads to a significant decrease in the temperature of HAN complete decomposition. The volatile products emitted during thermal decomposition of HAN doped with AC were characterized by electron ionization mass spectrometry analysis. The primary products of HAN decomposition at different heating rates (m/z = 33 (NH2OH), m/z = 63 (HNO3), etc.) were determined. Significant reduction of NOx emissions during thermal decomposition of HAN was observed. It is shown that addition of AC reduces the amount of NOx gases up to 30%.
Zulkhair A. Mansurov, Rachid Amrousse, Keiichi Hori, Meiram K. Atamanov

Chapter 9. Combustion of Ammonium Perchlorate: New Findings

Abstract
The combustion characteristics of ammonium perchlorate (AP) monopropellant have been discussed. Both experimental and computational tools were utilized to explore AP combustion. Three different methods were used to determine the low-pressure deflagration limit (LPDL) of AP monopropellant. Method I and Method II are found to introduce the ignition dynamics and affect the LPDL. Method III (slow depressurization) is independent of ignition and pressure dynamics. The LPDL of AP is found to be 14 bar using method III. Silica grease is found to act as an insulator. The use of silica grease on the sides of pellet reduces the convective heat loss and both the burning rate and the temperature sensitivity of AP are found to increase. The burning rate and temperature sensitivity of AP at 70 bar are 10.66 mm/s and 0.0038 K−1, respectively. LPDL of AP with 1% of iron oxide (IO) and copper chromite (CC) is significantly lower due to reduced convective heat loss and the prominence of the catalytic effect, which was overlooked in literature. A two-dimensional, unsteady combustion model is used to simulate AP. The combustion parameters of the model are suitably updated and a good match is obtained with the experimentally observed burn rate, pressure index, and temperature sensitivity.
Kumar Nagendra, Chaitanya Vijay, Mahesh Ingole, P. A. Ramakrishna

Chapter 10. Recent Achievements and Future Challenges on the Modeling Study of AP-Based Propellants

Abstract
In the past decades, studies on modeling of the combustion process of ammonium perchlorate (AP) and AP-based propellants have facilitated to support the existing experimental results and more completely, the understanding of the physical and chemical mechanisms during the reaction processes. The development of a large spectrum of models allows more accurate prediction of the structural properties and combustion behaviors of composites that govern their performance. Despite the widespread use and wide investigations, a lot of general processes still remain challenges. It should be noted that currently the problem of analytical and theoretical determination of the burning rate of AP-based propellants (as well as other propellants) has not been solved. Here, the recent achievements in this field are described, many of which promise to contribute to the development of advanced models and new approaches. The emphasis of this chapter is put on recent researches in the combustion modeling of AP-based propellants, the problems of which are of very significant scientific and practical interest. Advances in this direction make it possible to better understand the physical nature of the combustion processes and determine the factors that control the law of burning rate.
Meiram K. Atamanov, Jie-Yao Lyu, Xiang Lyu, Qi-Long Yan

Chapter 11. Survey of Low-Burn-Rate Solid Rocket Propellants

Abstract
This chapter presents the topic of low-burn-rate composite solid rocket propellants. While the majority of presently developed systems require high burn rates, several applications benefit from propellants with decreased regression rates. This includes solid rocket motors as well as gas generators. Background descriptions of the general aspects that impact on the burn rate of composite propellants are provided. Focus is given to means that enable obtaining low regression rates. While operational chamber pressure and grain temperature enable burn rate adjustment, they are in a relatively narrow range for most applications. Temperature cannot be arbitrarily set because it is defined by the firing conditions for a given composition. As for pressure, its decrease leads to loss of performance and has a strong impact on the overall motor design, and may have to be avoided. Internal flow field optimization and inhibiting heat transfer into the propellant grain is also significant. However, for the most demanding applications, limiting or preventing propellant erosion is not a sufficient solution. Most importantly, burn rate moderation can be done via the use of coolants, which serve as the most popular burn rate suppressants. Over 100 additives, which were investigated worldwide are listed. Methods enabling burning moderation include influencing the kinetics of decomposition of the oxidizer and binder regression. Moreover, oxidizer particle size and packing are significant. Bimodal and trimodal oxidizer distributions are typically used. Particle dimensions, but also shape, impact on combustion. Also fuel particle size, shape, surface area and surface finishing are important for the regression rate. Furthermore, the use of alternative oxidizers to ammonium perchlorate may be considered. Challenges in development of low-burn-rate propellants are discussed. This includes obtaining necessary properties, performance and meeting system-level requirements for various applications. A review of historical developments of low-burn-rate propellants is given with information on the most recent advances. Compositions, their burn rate and performance, are discussed. Moreover, the impact of several low regression rate propellants on solid rocket motor design is provided. This includes material oxidation, nozzle erosion and expected heat loads. Finally, an outlook on further low-burn-rate propellant development and utilisation is given.
Adam Okniński, Paweł Nowakowski, Anna Kasztankiewicz

Chapter 12. Burning Rate of PVC—Plastisol Composite Propellants and Correlation Between Closed Vessel and Strand Burner Tests Data

Abstract
The objective of this study is to assess two different methods used to determine the burning rates of solid rocket propellants and to find a convenient correlation of the measured data. The well-known strand burner test (Crawford test) and the closed vessel test were employed. In order to clarify the relation between the two techniques, a composite propellant containing polyvinyl chloride (PVC) as matrix and ammonium perchlorate (AP) as an oxidizer is used. It is prepared using normal AP (without heat treatment, nPoAP) or porous AP (after heat treatment, PoAP). Dioctyl phthalate (DOP) or dibutyl sebacate (DBS) was used as plasticizer. The PVC-Plastisol propellant burning rate behavior with respect to pressure, oxidizer nature, and propellant composition is analyzed. The obtained results show an acceptable correlation between the two techniques over the pressure range from 5 to 25 MPa.
Abderrahmane Mezroua, Michel H. Lefebvre, Djalal Trache, Kamel Khimeche

Application of Energetic Materials in Chemical Propulsion

Frontmatter

Chapter 13. Modern Approaches to Formulation Design and Production

Abstract
Changes in technology and understanding are giving new options for the design and manufacture of energetic formulations, whether they are explosives or propellants. It is now possible to approach the problem of matching formulation to desired characteristics in a systematic manner. This approach can cover all aspects from conception to disposal and includes performance optimization. This chapter will discuss and illustrate this: beginning with the use of predictive modeling, based on known properties both of ingredients and of the required output, and also consider its use for the design of novel ingredients to support synthesis research. The options for the physical nature of the ingredients; size, shape, crystal habit, polymorph, etc., and the ways of treating these for use will also be discussed. Composition design follows from this together with the understanding and management of both ingredient and composition characteristics. The ability to design for safety and life will also be discussed as will the need for reduced and managed environmental impact throughout that life. This should include awareness of environmental impact in use and disposal. Finally, the approaches to processing will be considered. The aim is to argue that such an integrated approach is the most cost-effective and productive method of formulating for the future.
Adam S. Cumming

Chapter 14. Method of Model Agglomerates and Its Application to Study the Combustion Mechanisms of Al, Al+B, and Ti Particles

Abstract
The new experimental approach called “method of model agglomerates” has been developed for studying the metal particle combustion behavior and evolution. The approach is based on special samples that consist of non-metalized propellant-matrix with inserted finite number of metalized inclusions. In the combustion wave of matrix these dosed inclusions transform into individual burning particles of given size and structure. The main difficulties in the interpretation of the sampling data such as polydispersity of an ensemble of agglomerates, difference in the structure of individual agglomerates, and uncertainty in describing the motion of burning agglomerates can be overcome using the proposed approach. The valuable information on the combustion mechanisms of Al, Ti, and Al+B agglomerates at atmospheric and elevated pressure was obtained and reported in this chapter.
Oleg G. Glotov

Chapter 15. Deagglomeration and Encapsulation of Metal and Bimetal Nanoparticles for Energetic Applications

Abstract
Experimental studies of the thermal properties of metallized propellant matrices with composite nanoparticles of aluminum, nickel, and iron had been considered. Thermal, thermodynamic, and kinetic effects of the oxidation of encapsulated aluminum and bimetallic nanopowders had been determined. It has been shown that the use of encapsulated aluminum powders in high-energy material (HEM) compositions changes the characteristics of HEM components. In particular, the encapsulation of aluminum particles, with both active and passive binders, leads to an increase in the resistance of particles to the oxidation, improving their combination with HEM components and increasing their mixing rate.
Alexander Vorozhtsov, Marat Lerner, Nikolay Rodkevich, Georgiy Teplov, Sergei Sokolov, Elizaveta Perchatkina

Chapter 16. Effects of Innovative Insensitive Energetic Materials: 1,1-Diamino-2,2-Dinitroethylene (FOX-7) on the Performance of Solid Rocket Propellants

Abstract
The microstructure physico-chemical properties of 1,1-diamino-2,2-dinitroethylene (FOX-7) and the probable formation of FOX-7/CL-20 and FOX-7/HMX co-crystals were analyzed by scanning electron microscopy (SEM) and molecular dynamics (MD) simulation, respectively. Several industrial- and research-type of hydroxyl-terminated polybutadiene (HTPB), nitrate ester plasticized polyether (NEPE) solid propellants and composite modified double-base (CMDB) propellants containing different mass fraction of FOX-7 with the same nominal composition were prepared and experimentally analyzed. The effects of FOX-7 on the combustion properties (strand burning rate and pressure exponent) and hazardous properties as well as the associated thermal decomposition were investigated, and compared with those of the propellant without FOX-7. The results indicate that the energetic properties (theoretical specific impulse and density) of NEPE and CMDB solid propellants decrease with an increase in mass fraction of FOX-7 in the formulations with a partial replacement of HMX or RDX by FOX-7, while their mechanical sensitivities decrease significantly. The friction sensitivity and impact sensitivity of NEPE propellant decrease from 100% to 88% and from 27.5 cm to 38.0 cm, respectively. The burning rate and pressure exponent of NEPE solid propellant increase with a partial replacement of HMX by FOX-7 in the formulation; the burning rates of the CMDB propellants as well increase with increasing mass fraction of FOX-7 in the formulations, while the pressure exponent of CMDB propellant decreases from 0.88 to 0.75 in the pressure range of 2–22 MPa when 20% of RDX is replaced by FOX-7 in the formulation. The maximum tensile strength of NEPE solid propellant increases from 0.84 MPa to 1.06 MPa at +20 °C and from 0.68 MPa to 0.75 MPa at +50 °C, respectively, while the elongation of propellant decreases from 83.2% to 33.9% and from 86.1% to 32.5%, respectively. The maximum tensile strength and elongation of CMDB propellants containing FOX-7 are higher than those of propellant without FOX-7 at 20 °C. When RDX is substituted completely by FOX-7, σm is increased by 2.32% and εm is increased by 12.73%.
WeiQiang Pang, Luigi T. DeLuca, HuiXiang Xu, Ke Wang, XueZhong Fan, FengQi Zhao

Chapter 17. Simulation of Condensed Products Formation at the Surface of a Metalized Solid Propellant

Abstract
This article considers mathematical simulation of a process of condensed products formation near the surface of a burning solid propellant. These products include agglomerates and smoke oxide particles (SOP). The idea of predicting properties of these products is based on classification of propellants with various combustion regularities depending on formulation factors. For these types of propellants, the developed models are used to determine (estimate) the relations between the two main fractions, size of the agglomerates and SOP, parameters of the chemical composition and structure of the agglomerates. Validity of the used approaches is confirmed by comparing the calculation results and experimental data.
Valery A. Babuk, Nikita L. Budnyi, Alexander A. Nizyaev
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