Abstract:Fractions of β-HMX (β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities. Inclusion of an additional twelve nitramines into this scenario resulted in a series of partial relationships, which were determined from the molecular structure of these substances. It was also found that there is a relation between increasing heats of fusion of the nitramines studied and their decreasing friction sensitivities. Comparison of friction sensitivity with heats of fusion, ΔH_m,tr of the studied nitramines shows that the increase in ΔH_m,tr values is more or less connected with a decrease in friction sensitivity.

Abstract:The friction sensitivity (FS) of five linear and eight cyclic nitramines has been determined. Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values with thermal reactivity. Generally, increasing values of activation energies of non-autocatalyzed decomposition of the studied nitramines are connected with decreasing FS values. A similar trend was found in the relation between FS and hypothetical initiation temperature for 5% conversion of the nitramines after 50 μs of their thermolysis, however, if in the given series of nitramines their initiation reactivity is predominantly determined by the energy content of their molecules and closer similarity of their molecular structures, then the above-mentioned trend may be opposite. The found relationships were used for prediction and verification of the activation energy of non-autocatalyzed thermal decomposition of 2,5-dinitro-2,5-diazahexane.

Abstract:The friction sensitivities (FS) of five linear and eight cyclic nitramines have been determined. These FS values were compared with the respective detonation velocities,D, and with the dimensionless ratio created by relating the heat of explosion,Q_real, to the activation energy,E_a, of non-autocatalyzed thermal decomposition of the explosives concerned. For the nitramaines studied, these comparisons show a general trend of FSdecreasing with increasing energy content.

Abstract:The friction sensitivity (FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive (V_S,max) and negative (V_S,min) extremes of molecular surface electrostatic potentials V_S(r). While there is an ambiguous relationship between the V_S,max values and FS values, the decrease of FS is connected (more or less) with increase in V_S,min values.

Abstract:The relationship between the electrostatic sensitivity and the molecular structure for 16 kinds of nitramine compounds and 34 kinds of nitro aromatic compounds were established based on the theory of the electrotopological state (E-state). Quantitative structure-property relationship(QSPR) model by Multiple linear regression method were established. The correlation coefficient and standard deviation of the nitramine compounds were 0.782 and 0.217, respectively, and those of the nitro aromatic compounds were 0.717 and 0.195. Analysis of the model show that there is a better correlation between the electrotopological state indices for atom type and the electrostatic sensitivity of the nitro class energetic materials, and it can be used to predict the electrostatic sensitivity of nitro compounds effectively. The electrical condition of atoms affects the electrostatic sensitivity importantly.

Abstract:The crystal characteristics of decreased sensitivity RDX (D-RDX) and commercial RDX (RDX) were studied by optical microscopy with matching refractive index, scan electron microscopy (SEM), sink-float process and laser particles apparatus. It is found that there was obvious difference of crystal characteristics such as microstructure of inter crystalline voids, particle size and distribution, shape, morphology between D-RDX and commercial RDX. The crystal characteristics value of D-RDX were measured: average particle size being 283μm, the span of size distribution being 0.8, spherical degree being 0.85, smooth particle surface, explosive particles apparent density being above 1.798 g·cm^-3. The shock wave sensitivities of D-RDX and commercial RDX were measured using small scale-gap test, from which the decrease level of the shock wave sensitivity of D-RDX melted with TNT is 10%-15% and casted with HTPB is 31.4%. The difference of shock wave sensitivity of melted or casted explosive charge relates closely to the crystal characteristics of RDX.

Abstract:Impact sensitivity, friction sensitivity and thermal decomposition tests were applied to study the influence of different ferrocene derivatives on the sensitivities of ultra-fine AP/ferrocene mixtures. Experimental results showed that the ferrocenederivatives in this paper increase the impact and friction sensitivities of the ultra-fine AP/ferroceen mixtures. The impact sensitivities of the ultra-fine AP/ferrocene mixtures are not related to the Fe contents of ferrocene catalyst. However, the friction sensitivities of the ultra-fine AP/ferrocen mixtures are positively related to the Fe content of ferrocene catalyst. Some kinds of ferrocene catalysts, such as, SH-F-1, SH-F-2, SH-F-3, GFP and SH-F-5, present a new exothermic peak in DSC curve of ultra-fine AP/ferrocene mixture, show the greater thermal sensitivities.

Abstract:The effects of HMX crystalline inter voids, particle size, morphology and defects type on shock sensitivity were studied using standard gap test method. The shock initiation threshold of HMX/rap oil (76/24, wt.%) composition was detected with gap test where HMX was recrystallized to various qualities . Results show that the gap thickness decreases from 15.5 mm to 13.2 mm when the crystal apparent density increases from 1.8992 g·cm^-3 to 1.9016 g·cm^-3, and gap thickness increased from 13.0 mm to 14.3 mm with particle size increasing from 20 μm to 650 μm. The crystal defects type is major factors affecting shock sensitivity, and the shock sensitivities of HMX with twins defects is higher than that of without twin defects. The crystal morphology has almost no effects on shock sensitivity, when the crystal apparent density and particle size is same.

Abstract:α′,β,γ-Aluminum hydride (AlH₃) is often seen alone in generation of α-AlH3 with aether. Effects of these polymorphs on the thermal stability and safety of AlH₃ were studied. At room temperature stored 650 d, the existence of γ-AlH₃ increases the decomposition rate of AlH₃ from 2.13% to 5.15%. The existence of the impurity polymorphs increases the fricition sensitivity and impact sensitivity. Furthermore, the influence to the electrostatic sensitivity is much more than the others, and the numerical value of E₅₀ is five to ten times than the that of pure α-AlH₃ polymorphs.

Abstract:The geometrical structure of aluminum triazide was optimized at the B3LYP/6-311G^* level of theory. Its density, heat of sublimation and heat of formation of aluminum triazide were estimated theoretically, and explosion parameters was calculated and compared with TNT. According to the principle of zero oxygen balance, when it added into the composite explosive of AN and TNT, those parameters were predicted and compared with those of composite explosive containing the same quality of Al. The detonation heat, specific volume of explosion, detonation temperature, detonation velocity, detonation pressure and working capacity of aluminum triazide is 5170.20 kJ·kg^-1, 585.62 L·kg^-1, 5028.12 K, 9095.23 m·s^-1, 31.02 GPa, 1105.14 kJ·kg^-1respectively, indicating that its properties are better than those of TNT except detonation velocity and working capacity. Therefore it is a potential explosive compound. When the quality percentage of Al is 6%, the above parameters of the composite explosive of AN, TNT and aluminum triazide were 4351.49 kJ·kg^-1, 892.22 L·kg^-1, 3142.50 K, 8344.09 m·s^-1, 27.55 GPa, 1417.11 kJ·kg^-1 respectively. Aluminum triazide is a potential high-energy ignition agent，since it can improve the detonation heat, detonation temperature, detonation velocity, detonation pressure and working capacity of the composite explosive.

Abstract:Thermal analysis curves of two proportions of sulphur-free black powders were measured by differential scanning calorimetry (DSC) at heating rates of 2,5,10,20 ℃·min^-1. The data and thermal behaviors were contracted between sulphur-free black powder and ordinary black powder. On the base of experiment data, activation energy and pre-exponential factor of black powder were calculated according to Kissinger′s equation,Ozawa′s equation and Satava-Sesták′s equation. Results indicate that the initial exothermic temperature，heat release and mechanical sensitivity of sulphur-free black powder are lower than these of ordinary one when active energy is higher.

Abstract:The thermal decomposition process of HMX was studied by dynamic vacuum stability test (DVST) method. The activation energy and pre-exponential constant of thermal decomposition reaction of HMX were obtained by universal integral method and differential method. The results show that the mechanism functions of thermal decomposition reaction of HMX at different isothermal temperatures are different. The thermal decomposition process of HMX obeys Ginstling-Brounshtein equation with 3D mechanism in the temperature range of 100-110 ℃, parabola rule with 1D mechanism in the temperature range of 120-140 ℃ and Valensi equation with 2D mechanism at 150 ℃. Reaction rate constant (k) of the thermal decompositionreaction of HMX increases with temperature, but it does not accord with the Van′t Hoff rule. The amount of decomposition gases of HMX below 150 ℃ obtained by DVST are less than 2.0 mL·g^-1, showing that HMX has a good thermal stability. The Semenov equation obtained by the time(t) required to decompose 0.1% HMX at different temperature(T) is lnt_T=12157.95/T-19.0052. The effective storage life needed to consume 0.1% HMX at 25 ℃ deduced by this equation is 90.6 a.

Abstract:Traditional test methods for thermal sensitivity of solid energetic materials were summarized. Aiming at the limitation of the fact that these methods cannot be applied to liquid energetic materials, a method using Accelerating Rate Calorimeter (ARC) to test thermal sensitivity of energetic materials was put forward. The decompositions of four solid explosives Pentaerythritol tetranitrate (PETN), Hexogen (RDX), Octogen (HMX), 2,4,6-Trinitrotoluene (TNT) and two liquid energetic materials Nitroethane (NE), 2-Ethylhexyl nitrate (EHN) were studied by ARC. Kinetic and thermodynamics parameters were calculated and analyzed. Temperature corresponding different time to maximum rate under adiabatic condition (θ) was calculated. Thermal sensitivity of four solid energetic materials is PETN>RDX>HMX>TNT, which is consistent with the conclusion obtained by the traditional Wood′s alloy bath method, therefore ARC can be employed to the test of the thermal sensitivity of both solid and liquid 〖JP3〗energetic material. The thermal sensitivity order of six energetic materials from high to low is EHN＞PETN＞RDX＞HMX＞TNT＞NE.〖JP〗

Abstract:The thermal safety of polymer bonded explosive (PBX) specimen based on HMX and their compatibility with contacted materials, silicone rubber cushion and polyurethane adhesive were investigated by on-line chemical reactivity test (CRT) detection device developed by the authors. The results show that the PBX specimen has a good thermal stability. The concentrations of CO₂ and N₂O evolvedfrom the specimen are only 0.1 mL·g^-1 after heated at 100 ℃ for 1.15 months. In comparison with PBX specimen, the concentration of N₂O evolved from PBX specimen/silicone rubber cushion or polyurethane adhesive mixture has a very little increase, but the net gas evolution quantity of the two mixtures is small, indicating that PBX specimen and two contacted materials are compatible.

Abstract:In order to simulate the response of hexanitrostibene (HNS) pellets in exploding foil initiators under heat environment,sealed sample tubes were designed. The cook-off tests of HNS pellets in Φ3 mm×4 mm,Φ4 mm×5 mm and Φ4 mm×6 mm with TMD in charge density of 90%, were carried out at the heating rates of 3.3 ℃·h^-1, 5, 10 ℃·min^-1. The reaction responses were determined by the damage or distortion of the sample tubes,the damage of its vulnerable place and the depth of steel dents. The test results were compared with those of unsealed pellets. The results indicate that the responses of HNS pellets under sealed condition are severe and the initial reaction temperatures of sealed HNS pellets （302.5-314.7 ℃） are lower than that of unsealed ones（328-335 ℃）. Under the heating rate of 5 ℃·min^-1 or 10 ℃·min^-1, the initial reaction temperature decreases as the charge weight increases. The bigger charge structure accumulates heat more easily, and it′s more sensitive to heat.

Abstract:The influence factors of slow cook-off characteristic of solid propellant were studied with the object of HTPE propellant and GAP propellant by means of slow cook-off experimental device and thermocouple and pressure transducer, including composition, burning rate, heating rate, restriction condition, and free volume. HTPE propellant has a very excellent slow cook-off characteristic, hut the addition of HMX increases the response extent of slow cook-off, and free volume has not obvious effect on the response extent of slow cook-off. The burning rate from 10.1 mm·s^-1 to 32.2 mm·s^-1 and the heating rate from 3.3 ℃·h^-1 to 1 ℃·min^-1 have scarcely effect on the response extent of slow cook-off characteristic of GAP propellant. The response extent of slow cook-off becomes more violent after increasing restriction condition for HTPE propellant and GAP propellant.

Abstract:To understand the effect of aging on safety of explosive parts,the accelerated aging test of temperature 75 ℃, 100 d and temperature 65 ℃,180 d were done respectively. For the novel and accelerated aging explosive parts，the thermal explosion test, the fast cook-off test and the drop test were carried out, and the testing data were analyzed comparatively. Results show that the thermal explosion delay time of explosive cylinder are shortened, and the thermal safety are receded after accelerated aging. The deflagrating temperature is decreased with the deflagrating time is shortened for aging fast cook-off bomb, and the breach degree of deflagration on fast cook-off bomb shell is big. When deflagration droped from aging explosive parts, the over pressure of shock wave are big. The residual explosive of unreaction on target plank are fewer, and the impact safety are decreased.

Abstract:Three aging models, including Arrhenius,time-temperature superposition principle and neural network were used to comparatively study the aged HMX based PBX. And the lifetime was predicted when this explosives lost 0.1% of their total mass at 20 ℃ and when the lost 0.2% of the total mass at 50 ℃ and 60 ℃. Results show that the lifetime predicted from Arrhenius, time-temperature superposition principle, neural network are 390 years, 490 years and 15.2 years and 1127 d, 1180 d, 1375 d; and 182 d, 196 d, 220 d, respectively. It is stated that the results calculated by Arrhenius is agreed with that by Time-temperature superposition principle, and the neural network model is not an available when below the modeling temperature.

Abstract:Through designing dynamic tensile sample of PBX,selecting length of input bar and output bar,placing strain gauge in proper position,improving experiment methods based on properties of PBX which compressive strength was greater than tensile strength,it was realized dynamic tensile strength in the reflected split Hopkinson press bar (SHTB). It showed dynamic tests beared high tensile strength. Dynamic tensile strength of PBX attained 13 MPa in 30 s^-1 strain rate while quasi-static tensile strength was only 7 MPa. Through observed by SEM,quasi-static tension failure was different with dynamic tension failure because crack had different expand methods and temperature rise induced binder soften. Destroyed model in quasi-static tension was transcrystalline fracture and intergranular fracture and it was binder debonded in dynamic tension.

Abstract:The gun propellant shock wave sensitivity was investigated by the gap test, including single-base, double-base, triple-base and azide nitramine (DA) propellant with shape of globe, 6/7 and 17/19. The gun shock wave response of propellant was studied. The effects of gun propellant shape the shock wave sensitivity was investigated. Results indicate that the more energy ingredients (RDX, NG, DA), the higher the shock wave sensitivity of gun propellant is and the different kinds of energy ingredients affect the shock wave sensitivity differently. The bigger the gun propellant shape, the less the sample shock wave sensitivity is. On the base of these experiments, the concept of propellant ingredients shock wave sensitivity quantification count is putted forward, that can be used to study propellant shock wave sensitivity deep.

Abstract:In order to estimate the safety property parameters of 1,5-diazido-3-nitrazpentane (DIANP) in detail,experiments of heat stimulus and mechanical stimulus were conducted to gain the response of DIANP under different levels of stimulus. At the same time, TNT equivalence of DIANP was tested at different shock wave overpressure to identify the safety level of manufacture workshop. The experimental results show that: DIANP can′t be ignited by ignitor or flame, and the self-initiation temperature of DIANP is 226 ℃. The utmost aperture by Koenen that is 20.0 mm. The results in explosion percentage of impact sensitivity and friction sensitivity from test performed according to improved national military standard method is 75% and 26% respectively. The TNT equivalence of DIANP in the shock wave overpressure range of 0.02 MPa to 0.3 MPa is 0.4~0.6.

Abstract:In this work,deflagration to detonation(DDT) experiments of pressed PBXC03 with different confinements (shell length 420 mm, shell thickness 10 mm and 20 mm) were conducted. Electrical pins were used to measure reaction wave velocity in explosives. DDT intensity was estimated by observing shell fragments and analyzing velocity changes. According to the conditions of different high density explosive charge,a DDT calculating model was established. The explosive deflagration reactive flow model was adopted to describe explosive reaction process. The methods of separating elements and random invalidation stress were used to describe shell expansion and rupture. The effects of gas leakage and pressure reduction on explosive reaction were considered. DDT processes under different confinements (shell length 420 mm, shell thickness 5, 10, 20, 30 mm) were calculated. The results show that only high density PBXC03 with strong confinement (shell thickness 30 mm) may undergo DDT. Gas leakage and pressure reduction induced by weak confinement (shell thickness 5 mm) will restrict the occurrence of DDT.

Abstract:In order to study the influence of pressing density on impact safety, some explosive charges with different densities were pressed utilizing A-Ⅸ-Ⅱ explosive, composition B, and HMX-based aluminized explosive. The charges of A-Ⅸ-Ⅱ explosive with density distribution in some order in the radial direction were pressed. The impact load test was carried out using a 400 kg weight drop. Results show that, with density increasing, the detonation threshold of A-Ⅸ-Ⅱ explosive, composition B and HMX-based aluminiferous explosive increases. When the density of A-Ⅸ-Ⅱ explosive is more than 1.680 g·cm^-3, its detonation threshold has no obvious change, whereas the detonating thresholds of three kinds of explosive have a little difference. When the density of A-Ⅸ-Ⅱ explosive distributes irregularly, its detonation threshold is decreased a little, lower than that of symmetrical density,indicating that pressing density and its asymmetry of charge are two principal factors affecting impacting safety.

Abstract:Even though there are extensively studies on penetration dynamics, these studies mainly focused on the structure response and penetration depth of projectile. Almost no charge stability theory theoretical analysis method in the process of penetration has yet been reported. This paper derived a novel theoretical analysis method of charge stability in the process of penetration, which is based on the assumption of plastic stress-strain deformation relationship of main charge, friction work, principle of thermal dynamics. The resistance function during penetration is based on the cavity expansion theory, using mass and monument equation, Hugoniot jump condition. The resistance forces are calculated with finite difference method and Newton′s Second law. The temperature rising between explosive-casing interfaces due to friction can be estimated with the input resistant force function. The novel theory shows that charge stability strongly depends on the maximum length of charge and overload characteristic of charge. In addition, the location of maximum temperature rising can be determined if the diameter of charge is given. The analytical results of this study provide the physical and geometry parameters, which can used as an important reference of charge design.

Abstract:The response characterastics and the impact factors of typical propellant charges were discussed in terms of general methods of tailoring the propellants to counter mechanical threats by the bullet impact,where bullet type is a 12.7 mm armor-piercing projectile,and the impact velocity is (850±20) m·s^-1. The results show that there are obvious correlations with the propellant compositions,forms and the piercing depth in the vulnerability response extents by the bullet impacts,but the energy level of propellants. Also,there are obvious influence on the propellant vulnerability response for the restrained conditions to the propellants. The typical propellants have no violent reaction in the weaker restrained conditions.

Abstract:The influence of solid propellant on warhead damage effect was studied by these quantitative parameters including lead cylinder compression value,lead block volume,shock wave overpressure and impulse. Influencing factors that effect lead cylinder compression value of warhead charge/propellant system was also discussed. The results show that four kinds of propellants all could enhance lead cylinder compression value of warhead charge/propellant system in different degrees. Contribution to lead cylinder compression value of warhead charge/ propellant system by four groups HTPB propellant is more than that by three groups HTPB propellant (HTPB-3). Increased percentage of lead block volume is 81.4% and 54%,respectively. When scaled distance ranges from 3.5 m·kg^-1/3 to 12.5 m·kg^-1/3,HTPB-3 contributes to shock wave overpressure TNT equivalence and impulse TNT equivalence of 1 kg PBXN/0.6 kg HTPB-3 system by an increase of 18.7% and 19.7%,respectively.

Abstract:In order to explore the hazard property of the RDX-CMDB propellant prepared by screw-extrusion technique， typical experiments including friction sensitivity, impact sensitivity, detonator sensitivity, gap, deflagration-to-detonation transition (DDT), drop, thermal stability,explosion temperature, slow cook-off, and electrostatic sensitivity were carried out. Results show that the propellant does not combust dropping freely from 10 m height, combusts under 164.2 ℃ during slow cook-off test, and detonats under 18 mm-thick organic glass by the shock-wave, and the friction sensitivity and 50% drop height of impact sensitivity was 2% and 26.3 cm, respectively, and the 50% ignition energy by electrostatic spark is 208.46 mJ, which indicating that the propellant has fair thermal stability,is insensitive to the mechanical stimulation, and is sensitive to shock-wave stimulation. The hazard rating of the propellant is 1.1.

Abstract:The structure of grinding and mixing machine was studied for the security perspective. The production limit experiment was carried out. Plugging material conditions and the detonation velocity of explosive were observed via adjusting operation parameters: feeding speed, scraper angle, grinding and mixing machine speed. The safety of the grinding and mixing machine was analyzed and discussed. Results show that when the speed of the grinding and mixing machine is 22.8 r·min^-1, the feeding speed 4 t·h^-1, the scraper angle 24°.

Abstract:With ethyl cyanoacetate as starting materials,3-aminofurazan-4-carboxylic acid(AFCA) was prepared through one-pot reaction in 46% yield. And 3-aminofurazan-4-monomethyl alcohol(AFMA) was synthesized by reduction reaction of AFCA through NaBH₄/ZnCl₂ system. 3-Nitrofurazan-4-monomethyl alcohol(NFMA) was obtained by oxidation of AFMA through H₂O₂/H₂SO₄ system. 3-Nitrofurazan-4-chloromethylene(NFCM) was obtained by chlorination of NFMA and SOCl₂. And 3-nitrofurazan-4-monomethyl ether(NFME) was synthesized by etherification reaction of NFCM and sodium methoxide in 45% yield. Their structures were characterized by FT-IR, MS, NMR and DSC-TG, and sensitivity and heat of combustion of NFME were measured. The results show NFME has a low melting point of -67 ℃ and is insensitive to impact and friction. NFME decompose at 169.9 ℃, and its standard combustion heat is 18628.8 kJ·kg^-1, formation enthalpy 1694.4 kJ·mol^-1, higher than nitrate plasticizer Bu-NENA, TMETN, BTTN and NG.

Abstract:Composite energetic materials that contained 85% hexogen(RDX), 3.75% aluminum and 11.25% iron oxide(Fe₂O₃) were obtained by sol-gel template and supercritical CO₂ fluid drying technology, and characterized by scanning electron microscope (SEM). Its particle size distribution is from 50 nm to 150 nm. Its impact and friction sensitivity test results show: comparison with raw RDX, the characteristic height (H₅₀) of the sample is 27.7 cm higher than that of RDX (2.5 kg, 22.5 cm), and percentage of explosion is 88% lower than that of RDX(90°, 3.92 MPa, 96%). The detonation velocity of the composition is 7185 m·s^-1 with 1.55 g·cm^-3 pressed density. It is identified as nano-composite energetic materials with insensitivity and high energy density.

Abstract:Using ADCI and large excess sodium nitrite as the raw materials, a one-pot synthesis of NDCI was reported, and its molecular structure was characterized by IR, 13C NMR, 15N NMR and X-ray diffraction analysis.

Abstract:RDX single crystals growing in two different solvents and cutting/polishing conditions were investigated.It is revealed that solvent properties have a important role in the morpholopy and crystal quality of RDX single crystals which can be machined into single crystal slices with 1mm~20mm thickness and used for the test of mechanic properties and initiation mechanism.

Abstract:This paper introduces a low-cost preparation technology of high explosive DNTF which fit the demand of weapons projection.

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