scholarly journals Study on Indium (III) Oxide/Aluminum Thermite Energetic Composites

2021 ◽  
Vol 5 (7) ◽  
pp. 166
Author(s):  
Pierre Gibot ◽  
Estelle Puel
Keyword(s):  
Energetic Materials ◽  
Combustion Velocity ◽  
Heat Of Reaction ◽  
Confined Geometries ◽  
Gas Generation ◽  
Aluminum Nanopowder ◽  
Heats Of Reaction ◽  
Energetic Composites ◽  
First Time ◽  
Combustion Speed

Thermites or composite energetic materials are mixtures made of fuel and oxidizer particles at micron-scale. Thermite reactions are characterized by high adiabatic flame temperatures (>1000 °C) and high heats of reaction (>kJ/cm3), sometimes combined with gas generation. These properties strongly depend on the chemical nature of the couple of components implemented. The present work focuses on the use of indium (III) oxide nanoparticles as oxidizer in the elaboration of nanothermites. Mixed with an aluminum nanopowder, heat of reaction of the resulting Al/In2O3 energetic nanocomposite was calculated and its reactive performance (sensitivity thresholds regarding different stimuli (impact, friction, and electrostatic discharge) and combustion velocity examined. The Al/In2O3 nanothermite, whose heat of reaction was determined of about 11.75 kJ/cm3, was defined as insensitive and moderately sensitive to impact and friction stimuli and extreme sensitive to spark with values >100 N, 324 N, and 0.31 mJ, respectively. The spark sensitivity was decreased by increasing In2O3 oxidizer (27.71 mJ). The combustion speed in confined geometries experiments was established near 500 m/s. The nature of the oxidizer implemented herein within a thermite formulation is reported for the first time.

scholarly journals Taming nitroformate through encapsulation with nitrogen-rich hydrogen-bonded organic frameworks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jichuan Zhang ◽  
Yongan Feng ◽  
Richard J. Staples ◽  
Jiaheng Zhang ◽  
Jean’ne M. Shreeve
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Energetic Materials ◽  
Decomposition Temperature ◽  
High Oxygen Content ◽  
The Poor ◽  
Simple Preparation ◽  
First Time ◽  
Hydrogen Bonded

AbstractOwing to its simple preparation and high oxygen content, nitroformate [−C(NO2)3, NF] is an extremely attractive oxidant component for propellants and explosives. However, the poor thermostability of NF-based derivatives has been an unconquerable barrier for more than 150 years, thus hindering its application. In this study, the first example of a nitrogen-rich hydrogen-bonded organic framework (HOF-NF) is designed and constructed through self-assembly in energetic materials, in which NF anions are trapped in pores of the resulting framework via the dual force of ionic and hydrogen bonds from the strengthened framework. These factors lead to the decomposition temperature of the resulting HOF-NF moiety being 200 °C, which exceeds the challenge of thermal stability over 180 °C for the first time among NF-based compounds. A large number of NF-based compounds with high stabilities and excellent properties can be designed and synthesized on the basis of this work.

Effect of Heat of Reaction on Temperature Distribution and Acid Penetration in a Fracture

1980 ◽  
Vol 20 (06) ◽  
pp. 501-507 ◽  
Author(s):  
M.H. Lee ◽  
L.D. Roberts
Keyword(s):  
Temperature Distribution ◽  
Thermal Energy ◽  
Balance Equation ◽  
Reaction Rate ◽  
Energy Equation ◽  
Fluid Temperature ◽  
Heat Of Reaction ◽  
Mass Balance Equation ◽  
Acid Rock ◽  
First Time

Abstract In a fracture acidizing treatment the acid reacts with the fracture faces. This acid/rock reaction generates heat that causes the acid temperature itself to increase. To predict accurately the temperature profile and acid spending rate of acid traveling down a hydraulically created fracture, this heat must be considered.Since the heat generated by reaction depends on the reaction rate, the thermal energy equation must be coupled with the acid spending equation. A model has been developed that, for the first time, examines the effect of the heat of reaction on fluid temperature and acid penetration in a fracture. Some sample calculations have also been made to illustrate the effects of the most important parameters on acid penetration in a fracture. Introduction Acid hydraulic fracturing is a common method of stimulating a reservoir. Acid selectively reacts with, and dissolves, portions of the fracture wall so that a finite fluid conductivity remains when the well is returned to production. An important aim in designing such fracturing treatments is determining the distance that live acid will penetrate down the hydraulically induced fracture. This distance is usually called the acid penetration distance and is essential to estimate the production improvement from a given treatment.Because of its importance in predicting stimulation ratio, acid penetration in fractures has been studied by numerous investigators. They assumed the temperature in the fracture was uniform. In real fractures, however, the temperature will vary from the wellbore to the tip of the fracture. Therefore, the assumption of constant temperature seems to be an oversimplification.Whitsitt and Dysart were among the first to study the temperature distribution in a fracture. They constructed a model but it could be applied only to a nonreacting fluid flowing in a fracture because the heat generated by an acid/rock reaction was not considered. In a fracture acidizing treatment, the acid is reacting with the rock walls. This acid/rock reaction generates heat, which causes the acid temperature itself to increase. To predict accurately the temperature profile along the fracture, this heat also must be considered. A model has been developed that, for the first time, examines the effect of the heat of reaction on fluid temperature and acid penetration distance. Mathematical Development The mathematical model is a modification of that introduced by Whitsitt and Dysart to allow for the heat of reaction in the energy-balance equation. Since the heat generated by the acid reaction also depends on the reaction rate, the thermal-energy equation is coupled with the mass-balance equation. These two equations must be solved simultaneously .The model for acid spending in a fractures is illustrated in Fig. 1. The fluid leakoff velocity Vw is assumed constant over the fracture length. Assuming steady-state flow in a vertical fracture and constant fluid properties, the mass-balance equation for acid flowing in a fracture is ................(1) SPEJ P. 501＾

Overview of Nanoscale Energetic Materials Research at Los Alamos

2005 ◽  
Vol 896 ◽  
Author(s):  
Steven F. Son ◽  
Timothy Foley ◽  
V. Eric Sanders ◽  
Alan Novak ◽  
Douglas Tasker ◽  
...  
Keyword(s):  
Energetic Materials ◽  
Chemical Potential ◽  
Optical Measurements ◽  
Los Alamos ◽  
Gas Gun ◽  
Front Position ◽  
Materials Research ◽  
Ignition And Combustion ◽  
Peak Pressures ◽  
First Time

AbstractMetastable Intermolecular Composite (MIC) materials are comprised of a mixture of oxidizer and fuel with particle sizes in the nanometer range. Characterizing their ignition and combustion is an ongoing effort at Los Alamos. In this paper we will present some recent studies at Los Alamos aimed at developing a better understanding of ignition and combustion of MIC materials. Ignition by impact has been studied using a laboratory gas gun using nano-aluminum (Al) and nano-tantalum (Ta) as the reducing agent and bismuth (III) oxide (Bi2O3) as the oxidant. As expected from the chemical potential, the Al containing composites gave higher peak pressures. It was found, for the Al/Bi2O3 system, that impact velocity under observed conditions plays no role in the pressure output until approximately 100 m/s, below which speed, impact energy is insufficient to ignite the reaction. This makes the experiment more useful in evaluating the reactive performance. Replacing the atmosphere on impact with an inert gas reduced both the amount of light produced and the realized peak pressure. The combustion of low-density MIC powders has also been studied. To better understand the reaction mechanisms of burning MIC materials, dynamic electrical conductivity measurements have been performed on a MIC material for the first time. Simultaneous optical measurements of the wave front position have shown that the reaction and conduction fronts are coincident within 160 μm.

Heats of formation of RuO4, RuO42−, and related compounds

1969 ◽  
Vol 47 (4) ◽  
pp. 581-586 ◽  
Author(s):  
E. E. Mercer ◽  
D. T. Farrar
Keyword(s):  
Sodium Periodate ◽  
Heats Of Formation ◽  
Basic Solution ◽  
Heat Of Reaction ◽  
Kcal Mole ◽  
Heats Of Reaction ◽  
Related Compounds

The heat of reaction of ruthenium metal with bromine in basic solution, according to the equation[Formula: see text]has been measured calorimetrically. In addition, the heat of oxidation of barium ruthenate hydrate by sodium periodate to form RuO4(aq) has been determined. From these heats of reaction, and several other heats measured here, the heats of formation of several ruthenium species have been calculated. The more important of these are: Na2RuO4(aq), ΔHf = −224.1 ± 0.8; RuO42−(aq), ΔHf = −109.4 ± 1.0; RuO4(aq), ΔHf = −57.5 ± 1.1; RuO4(l), ΔHf = −57.0 ± 1.1 kcal/mole.

Self-Blowing Process of Al Foam Assisted by Exothermic Reaction

2006 ◽  
Vol 519-521 ◽  
pp. 1335-1340 ◽  
Author(s):  
Makoto Kobashi ◽  
Naoyuki Kanetake
Keyword(s):  
Aluminum Foam ◽  
Liquid Aluminum ◽  
Exothermic Reaction ◽  
External Source ◽  
Processing Parameters ◽  
Hydrogen Gas ◽  
Heat Of Reaction ◽  
Aluminum Foams ◽  
Gas Generation ◽  
Reactive Powder

Aluminum foam is a class of porous materials; in which closed pores are produced by a gas generation in liquid (or semi-liquid) aluminum. Aluminum foams are, generally, fabricated by heating a foamable precursor (a powder compact consisting of aluminum and TiH2 powders). Decomposition of TiH2, which is followed by a hydrogen gas release, produces bubbles in molten aluminum. In this research, aluminum foam was fabricated with the help of a chemical exothermic reaction. Titanium and boron carbide (B4C) powders were blended in the Al-TiH2 precursor as reactive powder elements. When one end of the precursor was heated, a strong exothermic reaction between titanium and B4C took place (3Ti + B4C 􀃆 2TiB2 +TiC + 761KJ), and the neighboring part of the precursor was heated by the heat of reaction. Hence, once the reaction happens at the end of the precursor, it propagates spontaneously throughout the precursor. The blowing process takes place at the same time as the reaction because aluminum melts and TiH2 decomposes by the heat of reaction. The advantage of this process is that the energy to make aluminum foam is not necessarily supplied form the external source, but generated form inside of the precursor. Therefore the blowing process is self sustainable (Self-Blowing Process). In this work, the effect of processing parameters on the Self-Blowing Process was observed. The processing parameters we focused on were blending ratio of the starting powders (aluminum, TiH2, titanium, B4C) and heating methods.

Heats of Reaction of Natural Rubber with Sulfur

1970 ◽  
Vol 43 (6) ◽  
pp. 1275-1293 ◽  
Author(s):  
N. Bekkedahl ◽  
J. J. Weeks
Keyword(s):  
Hydrogen Sulfide ◽  
Standard Deviation ◽  
Natural Rubber ◽  
Volume Change ◽  
Side Reaction ◽  
Enthalpy Change ◽  
Heat Of Reaction ◽  
Use Of Data ◽  
Heats Of Reaction

Abstract An adiabatic copper calorimeter was used to determine the heats of vulcanization of pale crepe natural rubber with sulfur for mixtures varying in composition from 0 to 32 per cent added sulfur. The side reaction that produces hydrogen sulfide was avoided by using reaction temperatures near 155° C. Heats of reaction at 25° C and at 155° C are reported. The enthalpy change at 25° C for compounds containing up to about 18 per cent sulfur is given in joules per gram of vulcanizate by the equation, ΔH25=−21.1·S with a standard deviation of 11 J/g. Here S is the percentage of combined sulfur. Above 18 per cent sulfur the heat of reaction at 25° C remains approximately constant at 380 ± 8 J/g. A comparison is made between the heat of vulcanization and the volume change on vulcanization, both as functions of combined sulfur, by making use of data in the literature.

The solubility of potassium from soil illites. V. Interlayer hydrogen ions; heats of reaction; and synopsis

Soil Research ◽  
1967 ◽  
Vol 5 (2) ◽  
pp. 203 ◽  
Author(s):  
BM Tucker
Keyword(s):  
Calcium Chloride ◽  
Calcium Ions ◽  
Temperature Rise ◽  
Chloride Solution ◽  
Calcium Chloride Solution ◽  
Hydrogen Ion ◽  
Heat Of Reaction ◽  
Hydrogen Ions ◽  
Kcal Mole ◽  
Heats Of Reaction

When potassium is readsorbed at interlayer sites in soil illites after displacement in calcium chloride solution, hydrogen ions are released in proportions ranging from 1/6 to 1/10 of the potassium adsorbed. This supports the conclusions of earlier work that release of potassium by calcium ions from these sites requires the intervention of hydrogen ions in the approximate ratio of one hydrogen ion to three calcium ions. The release of potassium increased about 1.4 times for a temperature rise from 10 to 30�C. The heat of reaction was 3 or 4 kcal/mole potassium released. This is consistent with a reaction between ions and charged sites as the heats of many ionic reactions are of this magnitude; and it appears to be less than the heats of decomposition of the clay mineral lattice. A summary of the findings of Parts I-V of this series appears in the Synopsis

Heat of Reaction Measurements of Sodium Borohydride Alcoholysis

2005 ◽  
Author(s):  
Jinsong Zhang ◽  
T. S. Fisher ◽  
Jay P. Gore ◽  
P. Veeraraghavan Ramachandran
Keyword(s):  
Ethylene Glycol ◽  
Sodium Borohydride ◽  
Aqueous System ◽  
Heat Of Reaction ◽  
New Approach ◽  
On Demand ◽  
Heats Of Reaction ◽  
Prior Literature ◽  
Storage Methods ◽  
The Cost

On-board hydrogen storage has been identified as one of the most challenging technical barriers to the transition from gasoline to hydrogen powered vehicles. The Hydrogen-On-Demand™ system patented by Millenium Cell Inc. uses sodium borohydride and water to generate hydrogen when needed. The system has many advantages over other types of storage methods such as compressed hydrogen, liquid hydrogen and metal hydrides. Nevertheless, the cost of making and regenerating sodium borohydride is too high. A recently filed patent indicates that sodium borohydride alcoholysis (e.g. using ethylene glycol) may offer some advantages over the aqueous system in terms of regeneration, which may significantly reduce the cost to regenerate sodium borohydride. To begin evaluating the energy efficiency of this new approach, this work experimentally characterizes the heat of reaction of sodium borohydride with ethylene glycol. The heat of reaction was measured to be approximately 220 kJ/mol (exothermic). For the sodium borohydride and water reaction, two different heat of reaction values have been reported in prior literature. The present work shows that the heats of reaction for both sodium borohydride hydrolysis and alcoholysis are both near 220 kJ/mol exothermically.

scholarly journals Structure and Stability of Aromatic Nitrogen Heterocycles Used in the Field of Energetic Materials

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3232
Author(s):  
He-Hou Zong ◽  
Chuang Yao ◽  
Chang Q Sun ◽  
Jian-Guo Zhang ◽  
Lei Zhang
Keyword(s):  
Energetic Materials ◽  
Nitrogen Heterocycles ◽  
Lone Pair ◽  
Molecular Architecture ◽  
Lone Pair Electron ◽  
Nitrogen Lone Pair ◽  
The Individual ◽  
First Time ◽  
Broad Interest ◽  
Chemistry Community

Understanding the stabilization of nitrogen heterocycles is critical in the field of energetic materials and calls for innovative knowledge of nitrogen aromatics. Herewith, we report for the first time that nitrogen lone pair electron (NLPE) delocalization in five-membered nitrogen heterocycles creates a second σ-aromaticity in addition to the prototypical π-aromaticity. The NLPE delocalization and the attendant dual-aromaticity are enhanced as more carbon atoms in the ring are substituted by unsaturated nitrogen atoms. The presence of adjacent nitrogen atoms in the ring can enhance the aromaticity of the nitrogen heterocycles and improve in-crystal intermolecular binding strength but will decrease the firmness of the individual molecular architecture. Notably, such σ-aromaticity is not present in six-membered nitrogen heterocycles, probably due to the longer bonds and broader regions of their rings; therefore, six-membered heterocycles present overall lower aromaticity than five-membered heterocycles. This work brings new knowledge to nitrogen aromatics and is expected to inspire broad interest in the chemistry community.

scholarly journals Enhanced Crystal Stabilities of ε-CL-20 via Core-Shell Structured Energetic Composites

2020 ◽  
Vol 10 (8) ◽  
pp. 2663 ◽  
Author(s):  
Honglei Zhang ◽  
Qingjie Jiao ◽  
Wanjun Zhao ◽  
Xueyong Guo ◽  
Dayong Li ◽  
...  
Keyword(s):  
Energetic Materials ◽  
In Situ Polymerization ◽  
High Energy ◽  
Morphological Characterization ◽  
Core Shell ◽  
Scanning Calorimetry ◽  
Polymer Bonded Explosives ◽  
Friction Sensitivity ◽  
Energetic Composites

2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a widely used high-energy explosive for the application of energetic materials. However, the phase transformation from ε-CL-20 to γ-CL-20 restrains its further application in polymer bonded explosives (PBXs) and propellants. To inhibit the phase transition of CL-20, dopamine was first used in an efficient and facile method of in situ polymerization to passivate CL-20 crystals. The core-shell microcapsule particles were obtained, and the morphological characterization demonstrates the formation of a dense core-shell structure. The differential scanning calorimetry (DSC) and in situ X-ray diffraction (XRD) test results show that the compact and dense coating delays the ε-CL-20 crystal transformation temperature by about 30 °C, which enhances thermal stability. In addition, with the coating via polymers, the friction sensitivity of ε-CL-20 crystals decreases significantly. The findings indicate a successful application of dopamine chemistry in high-energy explosives, which provides an attractive method to modify the properties of CL-20 crystals.

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