The thermal decomposition characteristics of DNTF and 2 ,4 ,6‐trinitrotoluene (TNT) were investigated by means of differential scanning calorimetry at different heating rates .The kinetic parameters of thermal decomposition reaction ,critical tem‐perature of thermal explosion and thermodynamic parameters were calculated ,contrasted and analyzed by Kissinger methed .The results show that the thermal decomposition process of DNTF is different with TNT ,it occurs in two stages and the first acts as the major part .The activation energy of DNTF is 168 .85kJ/mol ,which is about 58kJ/mol higher than that of TNT ,revealing that DNTF has a good thermal stability at low temperature .However ,all the other thermodynamic parameters of DNTF are higher than those of TNT except the free energy of activation .The decomposition peak temperatures and critical temperature of thermal explosion of DNTF are lower than those of TNT .So ,the thermal stability of DNTF is poorer than that of TNT .
The thermal decomposition process of TATB was studied by DSC-TG.The activation energy(E),pre-exponential factor(A),rate constant at 120℃(k120)were calculated based on the DSC and TG-DTG curves at heating rates of 5,10,15 and 20K/min.The enthalpy of activation,entropy of activation and free energy of activation for TATB decomposition reaction at the temperature of decomposition peak at a heating rate of 5K/min were calculated.The thermal explosion characteristics of TATB in 1-ethyl-3-methylimidazolium acetate/DMSO([Emim]Ac/DMSO)solvent were studied by the small capacity test method.Results show that the values of E,calculated by Kissinger and Ozawa′s methods A and k120 of TATB decomposition reaction are 212.1 and212.0kJ/mol,respectively.Aand k20 calculated by formulas of Rogers and Arrhenius are 5.87×1016s-1 and 3.87×10-12s-1,respectively.The enthalpy of activation,entropy of activation and free energy of activation for TATB decomposition reaction at the temperature of decomposition peak at a heating rate of 5K/min are 206kJ/mol,61.42J/(K·mol)and 167.39kJ/mol,respectively.The critical explosion temperature of TATB powder is336.6℃.TATB does not explode in the[EmimAc/DMSO]solvent.
Six furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants have been investigated. It was shown that the use of some furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants can considerably increase ballistic parameters compared with HMX if the compounds under consideration contain difluoramine groups. And the use of the compounds under consideration may be successful only in the presence of an active binder and 10%-30% of AP or ADN as additional oxidizers.
To investigate the effect of nano-nickel powder with particle size of 50 nm on the combustion properties of AlCMDB and CL-20-CMDB propellants,the propellant samples were prepared through the rolling-absorption method.The burning rates of the propellants were measured by the target line method and the pressure exponents were calculated.The reason of how nano-nickel powder affect the combustion properties of Al-CMDB propellant was studied by flame photo,burning wave,DSC,morphology and elemental analysis of flameout surface.The results show that in Al-CMDB propellant,adding nano-nickel powder can greatly improve the burning rate and reduce the pressure exponent of the propellant.The burning rate of the propellant at 10 MPa reaches 35.59mm/s,the pressure exponent between 8-20 MPa reduces from0.43 to 0.17,and the propellant appears mesa effect between 15-20 MPa when adding 0.7%(mass fraction)nano-nickel powder into the Al-CMDB propellant.In CL-20-CMDB,adding 0.5%(mass fraction)nano-nickel powder to CL-20-CMDB propellant can increase the burning rate of the propellant greatly at 4-10 MPa,the pressure exponent between 8-20 MPa is about 0.01 and the propellant appears mesa effect between 15-20 MPa.
The reaction characteristics between double-core ferrocene derivative（DFD）and superfine-ammonium perchlorate（AP）were analyzed from the molecular structure of DFD.The structure-property relationship between molecular structure characteristics of DFD and the impact sensitivity of superfine AP/DFD binary system was investigated.The characteristic parameters of the DFD molecule used to analyze the reactivity between AP and DFD were found.The results show that the impact sensitivity of superfine AP/DFD binary system is directly related with the electrostatic potential of negative ferrocenyl of DFD and the average binding energy between NH 4 + and DFD.Due to the differences in molecular structure of DFD,the correlation between two parameters of DFD group of bridging groups as methylene and DFD group with symmetry of molecular structure and the impact sensitivity of ultrafine AP/DFD binary system is different.For the DFD of bridge group as methylene,the lower the electrostatic potential of negative ferrocenyl of DFD,and the greater the average binding energy between NH 4 + and DFD,the higher the impact sensitivity of superfine-AP/DFD mixture.For the DFD with symmetric structure,the lower the electrostatic potential of negative ferrocenyl of DFD and the average binding energy between NH 4 + and DFD,and the greater the molecular frontier orbital energy of DFD,the higher the impact sensitivity of superfine-AP/DFD mixture.
Starting from the related achievements of recent development in the field of energetic materials, the main research direction in this field was discussed, and the latest achievements of theoretical prediction of the physicochemical properties of energetic materials were described in particular, mainly including quantum chemistry, molecular dynamics or semi empirical QSPR modeling approaches to predict the research progress in sensitivity, combustion and detonation performances, reaction activity, curing mechanism and mechanical properties of energetic materials.The main technical barriers existed at present were summarized, including the lack of complete and unified standard experimental database on performances of energetic materials, no commercial software with independent intellectual property rights to calculate the energetic material properties, and international commercial software with reliable predictors of physical and chemical properties of energetic materials is limited to the detonation performance and combustion performance. Literature research shows that China needs to further strengthen the research in this field, and finally build a comprehensive software platform that can evaluate the performance and security of energetic materials.With 90 references.
2016年9月,以色列特拉维夫大学Michael Gozin教授来华讲学,期间与《火炸药学报》编辑部进行了座谈,并欣然接受邀请,担任编委,副主编赵凤起研究员为其颁发了聘书。Michael Gozin教授一直从事有机物分子、含能材料化合物等方面的研究,在荧光材料、高能含氮材料、有机金属框架材料和新型含能材料等方面取得了丰硕的成果。座谈中,Gozin教授表示2014年即开始关注
To research the effect of aging on the explosive performances,the accelerated aging test of three kinds of melt-cast explosives TNT/RDX,TNT/RDX/Al and TNT/HMX/Al stockpiled for a period of time were carried out.The micro morphology and safety properties of these explosives before and after aging were studied by scanning electron microscopy and vacuum stability test(VST).The mechanical sensitivities and detonation velocities of these explosives before and after aging were tested.The results show that after aging,the color of explosives becomes dark,the volume is expanded,and the mass is decreased.The amount of evolved gas of samples is less than 2mL/g.The thermal sensitivity of samples also has smaller change.The change in mechanical sensitivity is related to the components and aging mode of explosive.For the TNT/RDX,the detonation velocity gradually decreases with increasing the storage time,which is consistent with that of overall accelerated aging.The change trend of heat of detonation with increasing the storage time for the TNT/RDX/Al and TNT/HMX/Al is opposite,revealing that the aging mechanism may be different.
The investigation aims at the expansion of the basis of formulations of solid composite propellants by introducing new compositions with lower sensitivity to mechanic impact and improved thermal stability.The formulations based on trinitropyrazole（TNP）contains a binder（a hydrocarbon or active one）,aluminum and inorganic oxidizer ADN.The results show that a binary formulation TNP+active binder（18%-19%）（volume fraction）with no metal is well designed which would achieve high specific impulse（at Pc∶Pa=40∶1）of 248s,high density of 1.80g/cm3 and combustion temperature Tcabout 3 450K.In terms of energy,metal-free compositions with TNP lose a bit to those with HMX,only if HMX fraction in formulation is higher than 45%-50%.
In order to maximize density specific impulse of the Al/AP bipropellant powder rocket engine,the fire tests on Al/AP powder rocket engine were carried out with increasing the characteristic length of combustion chamber from 2.31 mto 12.62 m.Combustion performances of Al/AP mixtures such as ignition delay,burn time,combustion smoothness and intensity of vapor phase reaction in nitrogen under atmospheric pressure were studied by using spectrometer,CCD camera and CO2 laser igniter.Apparent packing densities of samples were measured.As an alternative fuel,the magnesium particles were also studied.The results show that,increasing chamber characteristic length from 2.31 mto 12.62 mproduces smoother combustion with ±2.43% maximum amplitude of chamber pressure oscillation.Flame of Al/AP mixture with 1μm Al particles is much more luminous than that with 10μm Al particles.And the continuous emission signal intensity of Al/AP mixture with 1μm Al particles at 568 nm exceeds the upper limit(65 000counts)of the spectrometer,rather than Al/AP mixture with 10μm Al particles with continuous intervals among combustion process and lower emission signal intensity at 568 nm of below 19 036 counts.Ignition delay and burn time of10μm Al particles are 3.65 times and 3.03 times as 1μm Al particles,respectively.But the maximumRAlOand packing density are14.3% and 21.3%less than 1μm Al powder,showing that smaller Al particles have better combustion performance but lower packing density.Although the theoretical specific impulse of the Mg/AP propellant is 95.6% of the Al/AP,its bulk density is 8%higher than 1μm Al powder,and the ignition delay is 90.3%shorter than 10μm particles.Flame images also show that magnesium can largely reduce the condensed phase deposition.
A high-speed scanning camera and wedge-shaped explosive configuration were used to study the shock initiation process of a new insensitive high explosive JBO-9X.The experimental results were numerically simulated and verified by LS-DYNA software.Results show that under the incident shock pressure of 6.9GPa,the time of shock to detonation of JBO-9Xis 1.5μs and the distance of shock to detonation is 7.9mm.When the shock wave just goes into the explosive,the ratio of occurred chemical reaction(λ)is 0.2.With increasing the distance of shock wave entering the explosive,the ratio of the chemical reaction occurred in the tested explosive increases gradually.Under the experimental conditions,when the incident shock pressure is 6.85 GPa,the distance of shock to detonation of JBO-9Xis 8.0mm.The growth curve of chemical reaction ratio with the distance of the shock wave entering the explosive is basically the same as the experiment.
A new kind of high-nitrogen compound bitetrazolyethane aminoguanidine monohydrate(CH7N4·C4H4N8·H2O)was prepared by an one-pot method.Its single crystal was characterized by FT-IR spectroscopy and elemental analysis and the crystal structure is measured by X-ray single crystal diffractometry. Its thermal properties were measured by TG-DTG and DSC. Its non-isothermal kinetic parameters were calculated by using Kissinger′s method and Ozawa′s method. Its heat of combustion was tested through an oxygen bomb calorimetry. Its detonation velocity (D) and detonation pressure (P) were computed by K-J formula and the mechanical sensitivity was tested. The results show that the crystal is monoclinic, its space group is C2/c (No.15) with cell parameters of a=1.1261(2)nm, b=0.71062(14)nm, c=2.7241(5)nm, β=95.95(3)°,V=2.1682(8) nm3, Z=4, and the theoretical density is 1.527g/cm3. It has good thermal stability with initial decomposition temperature of 289.3℃. Its non-isothermal kinetic parameters, apparent activation energy is 219.05kJ/mol, lg(A/s-1) is 38.61.The heat of combustion and enthalpy of formation are 9.515MJ/kg and 2892.2kJ/mol, respectively. The detonation velocity and detonation pressure are 6.95km/s and 19.3GPa. The impact sensitivity is higher than 50cm, and friction sensitivity is 0, revealing that the compound has low mechanical sensitivity and good thermal stability.
A new method based on tunable diode laser absorption spectroscopy(TDLAS) was introduced to measure the plume velocity of solid propellant charge, which was achieved by selecting one absorption line near 1392nm of the major combustion product-H2O through frequency calibration, cross arrangement of optical path, and using the Doppler frequency shift effect. In the static state test, the characteristic curves of the plume velocity and the pressure curve in the combustion chamber were compared, the feasibility of the technique for the measurement of the plume velocity of solid propellant was verified. A compact measurement prototype was developed, which is powered by lithium battery, the response time is 30ms, the mass is 2kg, the power consumption is less than 5W, the velocity is measured online and the result is stored.The dynamic test flight on the rocket sled was carried out,and the available results of plume velocity were obtained.The results show that TDLAS can be used to measure the dynamic plume velocity and it is an effective process for obtaining the online combustion parameters.
In order to investigate the effects of hexachlorocyclotriphosphazene (HCCT) as reducing rate agent on the burning rate, chemical stability, heat of detonation, mechanical sensitivity and mechanical properties of RDX-CMDB propellant, the compatibility of HCCT with the main components of RDX-CMDB propellant was tested and the performances of three kinds of RDX-CMDB propellants with different contents of HCCT were measured by target line method, methyl violet test, adiabatic method, etc. The results show that HCCT has good compatibility with the main components NC+NG and RDX of RDX-CMDB propellant, the addition of HCCT makes the burning rate of the propellant at the pressure of 2-6MPa decrease and the burning rate pressure exponent increase, the heat of detonation, fraction sensitivity and impact sensitivity all decrease, the tensile strength and elongation rate remain basically unchanged,and it has no effect on the chemical stability of the propellant.
A new energetic ionic salt, bis-2-methylimidazolium 1H,1H-5,5-bitetrazole-1,1-diolate (M2BTO),was synthesized using 1H,1′H-5,5′-bistetrazole-1,1′-diolate dihydrate(H2BTO·2H2O) and 2-methylimidazole as starting materials. Its structure was characterized by X-ray diffraction, FT-IR, 1H NMR, 13C NMR and elemental analyses.The thermal decomposition process and non-isothermal decomposition reaction kinetics of this energetic ionic salt were determined by differential scanning calorimeter (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analysis.The detonation velocity and detonation pressure parameters were theoretically calculated by Jacobs - Kamlet formula. The characteristic drop height of impact sensitivity (H50) was determined by WL-1 type impact sensitivity test instrument. The activation energy of the reaction was calculated by Kissinger′s method and Ozawa′s method. The results show that the crystal is triclinic space group P-1, with cell parameters of a=0.53860(5) nm, b=0.72676(6) nm,c=1.11149(11) nm, V= 401.00(6)×10-3nm3, ρ= 1.534 g/cm3, Z=1. The decomposition peak temperature of M2BTO is 542.1 K , a mass loss stage only exists on the TG curve at 503.5-568.2 K with the mass loss of 78.2%, showing that it has better thermal stability.The activation energy obtained by Kissinger′s method and Ozawz′s method are 134.7kJ/mol and 136.7 kJ/mol, respectively, the pre-exponential factor ln(A/s-1)=29.33. The theoretical calculation value of detonation velocity and detonation pressure are 7104 m/s and 20.23 GPa and the characteristic drop height H50 is higher than 61.0cm.
To explore the combustion characteristics of ethylenediamine bisborane hydrogen storage material with high hydrogen content in air, the ethylenediamine bisborane micro particles were prepared by a gas phase synthesis method. Its ignition and combustion parameters were tested by a continuous laser ignition test. The mechanism of combustion process was studied by pyrolysis experiments in nitrogen and air. The results show that ethylenediamine bisborane has the characteristics of short ignition delay time and small ignition energy. In a stagnation air flow at atmospheric temperature and pressure, as ignition power density reaches the order of magnitude of 109W/m2, the ignition delay time of micro ethylenediamine bisborane is 0.0002-0.0009s and minimum ignition energy is 0.0001J. The continuous laser ignition combustion process is divided into two stages, which produce bright blue flame and yellow flame, respectively. Combined with the pyrolysis behavior of materials in nitrogen and in air, it can be inferred that blue flame results from the combustion of hydrogen released in the first stage, and yellow flame shown in the second stage results from the combustion of pyrolysis products at higher temperature.
The nano-Fe2O3 was prepared by hydrothermal method, and then combined with Al nanoparticles using ultrasonic dispersion method to prepare superthermite Al/Fe2O3. The physical phase, composition, morphology and structure of the composite were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The differential scanning calorimetry (DSC) and the thermogravimetry with Fourier transform infrared analysis (TG-FTIR) were employed to investigate the effects of the superthermite Al/Fe2O3 on the thermal decomposition process of nitrocellulose (NC). The results show that the thermal decomposition reactions of Al/Fe2O3-NC composite and NC follow the same thermal decomposition mechanism with the Avrami-Erofeev equation of f(α)=1.5(1-α)[-ln(1-α)]1/3. The superthermite Al/Fe2O3 can reduce the activation energy of the decomposition reaction, the thermal ignition temperature and the critical temperature of thermal explosion of NC,and it plays a crucial role in promoting the O-NO2 bond cleavage of NC and secondary autocatalytic reactions in condensed phase.
In order to dynamically measure the light transmittance of plumesmoke distributed in a large space , a video-image test system for solid propellant plume-smoke shielding ability was established. The measuring images and the background images were processed to obtain the contrast of the measured image, and the measurement results of the neutral optical attenuator calibrate and convert into the transmittance. The test system was established according to the measurement model and the verification test was performed. The results show that the video image measurement method has a larger measurement field of view, it can obtain more information on smoke distribution etc., and can reduce the interference of the light radiation of environmental background. The data obtained from this method has good repeatability and good system stability, this method can be used for accurate measurement of the plume-smoke light transmittance of propellant.
The properties and compatibilities of solid propellant components 1,2,4-butanetriol trinitrate (BTTN), nitroglycerine (NG), cyclotetramethylenete-tranitramine (HMX), hydroxyl-terminated polybutadiene (HTPB), dioctyl sebacate (DOS) and ethyl centralite (EC) were studied by molecular dynamic simulation. In the COMPASS force field, the binding energy, cohesion energy density, solubility parameter of above-mentioned compounds and their blended systems and Flory-Huggins interaction parameter between the molecules of the blended systems were simulated and calculated. The compatibility between the propellant components was predicted by comparing the solubility parameter difference(Δδ) and Flory-Huggins interaction parameters etc. The nature of interaction between the molecules of components of mixed materials was revealed by analyzing the binding energy. The results show that BTTN and NG are compatible with EC,HTPB and DOS are a compatible system, and HTPB/NG, HMX/BTTN and HMX/NG systems are incompatible.
The crystal transformation and crystallization characteristics of ammonium nitrate(AN)were studied using Flash DSC method. The characteristic regulars corresponding to the transformation process were obtained, and the phase transformation kinetic parameters were calculated based on Kissinger′s equation. The results show that with the increase of heating rate from 100K/s to 5000K/s, the shape of each phase transformation peak of AN gradually widens. The starting temperature of the crystal transformation of Ⅴ→Ⅳ is significantly shifted to low temperature, and the starting temperature of the crystal transformation of Ⅳ→Ⅲ、Ⅲ→Ⅱ、Ⅱ→Ⅰis slightly shifted to high temperature. In cooling rate test from -10K/s to -3500K/s, there were obviously super-cooled phenomenon in the reversible phase transitions of AN, the peak temperature of the crystallization of AN, Ⅰ→Ⅱ,Ⅱ→Ⅲ,Ⅲ→Ⅳ are shifted to low temperature. The activation energies Ea of the crystallization and crystal transformation of Ⅰ→Ⅱ、Ⅱ→Ⅲ under two kinds of cooling rate range -10~-500K/s and -1000~-3500K/s are 761.11, 570.98, 700.71kJ/mol and 102.48, 82.16, 166.76kJ/mol, respectively. The pre-exponential factors ln (A/s-1) are -213.27、-183.76、-267.25 and-29.26、-26.71、-64.38,respectively.
