Showing papers on "Friction sensitivity published in 2017"

Nano-CL-20/HMX Cocrystal Explosive for Significantly Reduced Mechanical Sensitivity

Abstract: Spray drying method was used to prepare cocrystals of hexanitrohexaazaisowurtzitane (CL-20) and cyclotetramethylene tetranitramine (HMX). Raw materials and cocrystals were characterized using scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, Raman spectroscopy, and Fourier transform infrared spectroscopy. Impact and friction sensitivity of cocrystals were tested and analyzed. Results show that, after preparation by spray drying method, microparticles were spherical in shape and 0.5ź5źµm in size. Particles formed aggregates of numerous tiny plate-like cocrystals, whereas CL-20/HMX cocrystals had thicknesses of below 100źnm. Cocrystals were formed by CźHźO bonding between źNO2 (CL-20) and źCH2ź (HMX). Nanococrystal explosives exhibited drop height of 47.3źcm, and friction demonstrated explosion probability of 64%. Compared with raw HMX, cocrystals displayed significantly reduced mechanical sensitivity.

Crystal structure and morphology of β -HMX in acetone: A molecular dynamics simulation and experimental study

Abstract: Single crystals of β-Cyclotetramethylene tetranitramine (HMX) were prepared by the solvent evaporation method. The structure was then determined using infrared spectroscopy and single crystal X-ray diffraction. The modified attachment energy (AE) model was used to predict the morphologies of β-HMX in vacuum and in acetone. The morphology and sensitivity of HMX before and after recrystallization were characterized. The results of calculation showed that the (011) and (110) surfaces of β-HMX are of great morphological importance. The predicted β-HMX morphology agreed qualitatively with the SEM result. The sensitivity results show that recrystallization in acetone can effectively reduce the impact and friction sensitivities of β-HMX.

(E)-1,2-Bis(3,5-dinitro-1H-pyrazol-4-yl)diazene – Its 3D Potassium Metal–Organic Framework and Organic Salts with Super-Heat-Resistant Properties

Abstract: (E)-1,2-Bis(3,5-dinitro-1H-pyrazol-4-yl)diazene (H2NPA, 1) and its energetic salts, which are a series of new, energetic, highly heat-resistant, dense explosives, were synthesized. The explosives contain four nitro groups and an azo-bridged framework and were characterized by 1H and 13C NMR (in some cases 15N NMR) spectroscopy, IR spectroscopy, and elemental analysis. The crystal structures of K2NPA (a three-dimensional metal–organic framework, 3D MOF) and the guanidinium salt 4 were determined by single-crystal X-ray diffraction, and their properties (density, thermal stability, and sensitivity towards impact and friction) were investigated. The detonation properties were evaluated from the measured density and calculated heat of formation by the EXPLO5 v6.01 program. All of the salts exhibit thermal stabilities with decomposition temperatures ranging from 156 to 315 °C, high densities (1.70–2.15 g cm–3), high detonation velocities (8224–9083 m s–1), and high positive heats of formation (45.7–1040.1 kJ mol–1). The obtained 3D metal–organic framework explosive K2NPA combines exceptional thermal stability (Td = 315 °C) with a high density (d = 2.15 g cm–3) and possesses ideal calculated detonation velocity (vD = 8275 m s–1) and pressure (PCJ = 31.1 GPa) values. Moreover, its suitable impact sensitivity (IS) of 1.5 J and friction sensitivity (FS) of 60 N make K2NPA an outstanding, highly heat-resistant, green primary explosive. The guanidinium salt 4 also exhibits a high thermal stability (Td = 304 °C) that is superior to that of HMX, insensitivity to impact (IS > 40 J) and friction (FS > 360 N) comparable to those of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), and a high detonation performance (vD = 8391 m s–1).

Formation of Additive-Containing Nanothermites and Modifications to their Friction Sensitivity

Abstract: Nanothermites can provide high energy densities and reaction rates but can also display extreme friction sensitivities. Additives that provide friction modification offer the potential to reduce the friction sensitivity of nanothermites. In the present work, MoS2, graphene, and hexadecane additives were dispersed in MoO3 prior to nanothermite formation with the aim of reducing friction sensitivity. Nanothermites were subsequently prepared using a palmitic acid–passivated nano-aluminum (L-Al) and additive-containing nano-MoO3 by the resonant acoustic mixing of dry powders. In general, the incorporation of additives results in a reduction in friction sensitivity with the baseline minimum ignition friction rising from 10 to 120 N using 0.5% wt/wt micrometer-sized MoS2 or 5% wt/wt hexadecane. However, the relationships between loading and performance are complex and vary by additive; for example, the friction sensitivity dependence using micrometer-diameter MoS2 displays a maximum at 0.5% wt/wt and de...

Optimization of the key steps of synthesis and study of the fundamental physicochemical properties of high energy compounds — 4-(2,2,2-trinitroethyl)-2,6,8,10,12-pentanitrohexaazaisowurtzitane and 4,10-bis(2,2,2-trinitroethyl)-2,6,8,12-tetranitrohexaazaisowurtzitane

Abstract: The key steps of the synthesis of two high energy compounds, namely, 4-(2,2,2-trinitroethyl)-2,6,8,10,12-pentanitrohexaazaisowurtzitane and 4,10-bis(2,2,2-trinitroethyl)-2,6,8,12-tetranitrohexaazaisowurtzitane, were optimized. Their enthalpy of formation, density, impact and friction sensitivity, and thermal stability were experimentally determined.

Evaluation of 4‐(Dimethylsilyl) Butyl Ferrocene Grafted HTPB as a Burning Rate Modifier in Composite Propellant Formulation using Bicurative System

Abstract: High burning rate composite propellants are achieved by incorporation of fine particles of oxidizer, transition metal oxides, and liquid ballistic modifiers. However, they pose processing problems, inertness to the composition and migration related issues. To overcome such problems, an attempt was made to incorporate ferrocenyl grafted HTPB as a burning rate modifier by partly replacing HTPB from 10 % to 50 % using TDI/ IPDI bicurative system and to study their processability in terms of viscosity, mechanical, thermal, sensitivity, and ballistic properties. The data on viscosity reveal that there is a marginal enhancement in end of mix viscosity as percentage of ferrocenyl grafted HTPB increases. The mechanical data reveal that tensile strength and elastic modulus increases, whereas percentage elongation decreases compared to base composition. The results on thermal properties infer that, as the percentage of ferrocenyl grafted HTPB increases, onset decomposition temperature decreases. The impact and friction sensitivity data also envisage that sensitivity increases in comparison to base composition. The data on ballistic properties revealed that there is ca. 53 % increase in burning rate, while decrease in “n” value from 0.39 to 0.2 was obtained compared to base composition.

Sulfur-free propellant and preparation method thereof

Abstract: The invention provides sulfur-free propellant. The sulfur-free propellant is prepared from 35wt%-52 wt% of potassium perchlorate, 5 wt%-15 wt% of a filling agent, 8 wt%-20 wt% of a bonding agent, 5 wt%-18 wt% of calcium stearate and 10 wt%-30 wt% of potassium acid phthalate by taking the total weight of the sulfur-free propellant as a standard. The sulfur-free propellant is low in friction sensitivity, impact sensitivity and moisture absorption capacity and high in thrust, and meanwhile pollution to the environment is reduced.

Synthesis of 1-Amino-2,4-Dinitroimidazole Optimized by Online Infrared Spectroscopy and its Energetic Properties

Abstract: The optimization of the reaction conditions (solvent, reaction time, and aminating agent) for the synthesis of 1-amino-2,4-dinitroimidazole (3) by monitoring the reaction with online infrared spectroscopy is reported in this study. First, the thermal characteristics of 3 were studied by using differential scanning calorimetry (DSC; using heating rates of 2.5, 5, 10, and 20 K min-1 ), thermogravimetric analysis (TG), and the thermal explosion method. The Kissinger and Ozawa methods were used to calculate the average activation energy for the formation of 3; with logarithmic frequency factors (ln A) of 21.04 and 9.62, and activation energies (Ea ) of 98.68 and 102.28 kJ mol-1 , respectively. Compound 3 and its reaction precursors 2,4-dinitroimidazole (1) and 1,4-dinitroimidazole were characterized by single-crystal X-ray diffraction. Compound 3 is shown to have good energetic properties, as determined through EXPLO5 v6.02 and actual measurement. Furthermore, this energetic material is found to have low impact sensitivity (IS>40 J) and friction sensitivity (FS>360 N).

Exothermic compound for carbon dioxide gas blaster

Abstract: The invention provides an exothermic compound for a carbon dioxide gas blaster. The exothermic compound for the carbon dioxide gas blaster is prepared from, by mass, 10%-20% of perchlorate, 35%-55% of nitrate, 8%-15% of combustible, 3%-5% of sodium dodecyl benzene sulfonate, 3%-5% of boxwood powder, 4%-6% of dry method wood fibers, 3%-5% of CaF2, 4%-6% of aluminum powder and 2%-4% of phenolic resin. The combustible is selected from one or more of saccharose, glucose, starch and cellulose. The exothermic compound for the carbon dioxide gas blaster has the advantages of being fast in heating and large in heat value, is low in flame sensitivity, percussion sensitivity, friction sensitivity and static sensitivity, can eliminate potential safety hazards well, and provides convenience for production, transportation, storage and use.

Preparation and Characterization of Metalized Explosive Containing B and Al Powder

Abstract: Octagon (HMX) based metalized explosive containing boron (B)/aluminum(Al) compound powder, oxidizer ammonium perchlorate(AP) and binder hydroxyl-terminated polybutadiene(HTPB) was designed and prepared. The appearance morphology of B powder, Al powder and B-Al compound powder were observed by SEM. The effects of HMX and AP on the thermal oxidation characteristics of B and Al powder were investigated by TG-DSC. A deeper understanding of reaction kinetic mechanism of the B and Al powder was made. The sensitivities(impact sensitivity, friction sensitivity, electrostatic spark sensitivity, cap initiation sensitivity) and ignition and propagation properties for metalized containing B/Al were measured, which made a fully acknowledge of the safety under different external energy stimuli and ability of detonation propagation. The results show that there are many small particles of B powder on the surface of spherical Al powder in the B-Al compound powder. From room temperature(25 ℃) to 1000 ℃ under N2 atmosphere, although the pressures have an effect on the thermal decomposition peak temperature of HMX and AP, however partial oxidation of Al powder and B powder only occurs, whereas the combustion does not occur. The impact sensitivity, friction sensitivity and electrostatic spark sensitivity of the metalized explosives containing B and Al powder are 40%-80%, 100% and 3.83-6.40 kV respectively, and all the metalized explosives designed can be intiated by 8# industrial detonator, which indicates that the mechanical sensitivity of the metalized explosive containing B and Al powder without binder is high. The mechanical sensitivity is obviously lowered by adding desensitized HMX and AP, and it can be further lowered by adding polyurethane binder. By increasing the 20% content of polyurethane binder HTPB, the impact sensitivity and friction sensitivity of the HMX based metalized explosive containing B powder can be reduced less than 10% and 30%, respectively, revealing that the safety requirements for preparation and processing technology of mixed explosive can be satisfied. Additionally, the metalized explosive of Ф 50 mm can be intiated by 8# industrial detonator and can propagate stable detonation, showing a strong after-effect power ability.

Preparation and Sensitivity Measurements of Graphene Oxide-RDX Composite

Abstract: The effect of graphene oxide (GO) on the safety characteristics of 1,3,5-trinitro-1,3,5-triazinane (RDX) was studied in this work. Graphene oxide was prepared and was investigated to form a composite based on GO-RDX by solvent-antisolvent slurry technique. For comparison, different polymer bonded explosives (PBXs) based on RDX bonded by viton A, fluorel or polymethyl-methacrylate binders were studied and designed as RDX-Viton, RDX-Fluorel and RDX-PMMA respectively. Sensitivities to impact and friction of the presented samples as well as the pure RDX was measured. The ignition temperatures were determined and the activation energies were calculated by using the ignition delay method. Results of x-ray diffraction and scanning electron microscope proved that RDX crystals were coated by a thin layer of GO. The impact sensitivity of GO-RDX composite is lower than that of the other studied samples while the friction sensitivity is slightly higher. The ignition temperature of GO-RDX was lower than the other studied samples which indicates that the GO caused accumulation of the decomposition gaseous products and accelerated the decomposition process of RDX. GO is an interesting candidate material to be used for coating the explosive crystals instead of the polymeric matrices.

A testing arrangement for determining energetic material impact sensitivity and friction sensitivity

Abstract: The utility model discloses a testing arrangement for determining energetic material impact sensitivity and friction sensitivity, including quick -witted case, servo motor, trachea, pneumatic hammer, tracheal air outlet pipe hole respectively with the airtight intercommunication of pneumatic hammer's air inlet, quick -witted bottom of the case portion right side corresponds pneumatic hammer and is equipped with the sample striking test chamber body, movable mounting hits the pole subassembly in the sample striking test chamber body, hits the post subassembly and hits the corresponding setting of pole subassembly, servo motor, lead screw, ejector pin connect gradually, are equipped with the sample friction test chamber body in the sample striking test chamber body, and movable mounting has the traveller cover in the sample friction test chamber body, and two travellers about having in the traveller cover are equipped with the energetic material friction sensitivity sample about, between two travellers, and pneumatic hammer's piston hammer block bottom is corresponding with sample friction test chamber external wall position. The utility model has the characteristics of multifunction, impact sensitivity and friction sensitivity that can while testing energetic material.

Preparation method of 1,2-di(3,5-dinitro-1H-pyrazole-4-yl)diazene potassium salt structre and performance thereof

Abstract: The invention provides a preparation method of a green primary explosive with high energy and high temperature resistance 1,2-di(3,5-dinitro-1H-pyrazole-4-yl)diazene potassium salt (K2NPA) structure and performance thereof, the structure is a novel 3D MOF structure, and the invention belongs to the technical field of energetic materials. A synthetic method is as follows: a high temperature reaction is carried out for 4-amino-3,5-dinitro pyrazole (LLM-116), potassium hydroxide and potassium permanganate, acidification is carried out in order to obtain 1,2-bis(3,5-dinitro-1H-pyrazole-4-yl)diazene (H2NPA), a reaction is carried out for H2NPA and potassium hydroxide, and a target compound 1,2-di(3,5-dinitro-1H-pyrazole-4-yl)diazene potassium salt (K2NPA) is obtained. The energetic compound has a 3D MOF structure, density is 2.15g.cm , decomposition temperature is 314.9DEG C, calculated detonation velocity reaches 8249m.s , detonation pressure is 30.9GPa, degree of impact sensitivity is 1.5J, friction sensitivity is 60N, and electrostatic spark sensitivity is 0.8J; compared with lead azide, the decomposition temperature of the target compound is equivalent, the detonation velocity, the friction sensitivity, and the electrostatic spark sensitivity of the target compound are higher, and the impact sensitivity is lower; the primary explosive is easy to explode, explosion products do not cause heavy metal pollution, and the primary explosive is a novel green primary explosive with high energy and high temperature resistance. The synthetic method is simple, post-treatment only need filtering and recrystallization, tedious purification processes are avoided, and realization of industrialization is easy.

Introducing Tetrazole Salts as Energetic Ingredients for Rocket Propulsion

Abstract: Two tetrazole salts, hydroxylammonium 2-dinitromethyl-5-nitrotetrazolate (HADNMNT) and dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (HATO), were synthesized and characterized. HADNMNT is a new compound, whose structure was determined by 15N NMR experimentally and GIAO calculation, the thermal decomposition temperature, the explosion probabilities of impact sensitivity, and friction sensitivity of which were tested to be 141.9 °C, 96 %, and 100 %, respectively. The detonation parameters of HADNMNT were predicted to be equal to those of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). It was found theoretically that HADNMNT is a potential oxidizer for composite propellants to replace ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triazinane (RDX), HMX, and 2,4,6,8,10,12-hexanitro-,2,4,6,8,10,12-hexazaisowurtzitane (CL-20). Safety tests for HATO were performed, and results showed that HATO exhibits excellent thermal stability (the decomposition temperature is 230.3 °C, and the volume of the released gas is 0.30 mL·g−1 at 100 °C for 48 h) and low mechanical sensitivities (the explosion probabilities of impact sensitivity and friction sensitivity are 16 % and 24 %, respectively). The compatibilities of HATO with hydroxyl-terminated polybutadiene (HTPB), AP, RDX, and aluminum powder (Al) were reexamined to be good, using the vacuum stability test. Results from comparative study of HATO and RDX as ingredient for composite propellant showed that the composite propellant composed HATO offer the advantages of high burning rate and low mechanical sensitivities.

Testing device for measuring impact sensitivity and friction sensitivity of energetic material

Abstract: The invention discloses a testing device for measuring the impact sensitivity and friction sensitivity of an energetic material The testing device comprises a case, a servo motor, an air pipe and a pneumatic knocking hammer, wherein an air outlet pipe orifice of the air pipe is communicated with an air inlet of the pneumatic knocking hammer in a sealed manner; a test sample impact testing cavity corresponding to the pneumatic knocking hammer is formed in the right side of the bottom of the case; an impact rod component is movably mounted in the test sample impact testing cavity, and an impact column component is arranged corresponding to the impact rod component; the servo motor, a lead screw and an ejector rod are sequentially connected; a test sample friction testing cavity is formed in the test sample impact testing cavity; a sliding column sleeve is movably mounted in the test sample friction testing cavity; a left sliding column and a right sliding column are arranged in the sliding column sleeve; an energetic material friction sensitivity test sample is arranged between the left and right sliding columns; the positions of the bottom of a piston hammer body of the pneumatic knocking hammer and the outer wall of the test sample friction testing cavity correspond to each other The device has the characteristic of multifunction, and can be used for simultaneously testing the impact sensitivity and friction sensitivity of the energetic material

Heat insulation device and temperature control regulation device used for friction sensitivity tester

Abstract: The invention provides a heat insulation device and temperature control regulation device used for a friction sensitivity tester. The heat insulation device comprises a sealed two-layer heat insulation jacket, the outer wall of the heat insulation jacket is provided with through holes used for taking and placing a sample to be measured; a flow inlet is arranged under one side of the outer wall of the heat insulation jacket, and a flow outlet is arranged above the other side of the heat insulation jacket; and a measuring area of the friction sensitivity tester is arranged in an area formed by the inner wall of the heat insulation jacket, a liquid medium is input from the flow inlet before measurement and is output from the flow outlet, and the heat insulation of the measurement area is realized through circulation of the liquid medium. The heat insulation device and the temperature control regulation device used for the friction sensitivity tester have the characteristics of simple and compact structure, convenience in assembling and operating, fast heating and cooling rates, stable temperature, and guaranteeing of reliable running of the temperature control regulation device used for the friction sensitivity tester.