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Abstract:To study the ignition and combustion characteristics of suspended fuel containing metal particles, two kinds of high-density suspension fuels of HD-01 and quadricyclane(QC) with 5% aluminum nanoparticles(Al NPs) were prepared. The ignition delay of two kinds of suspended fuels at different pressure and temperature was measured by atomization shock tube. The apparent activation energy of ignition was obtained by fitting and calculating. The ignition and combustion mechanism of the suspension fuel were analyzed. The flow field images of ignition and combustion were recorded by high-speed camera. Results show that the suspended fuel can stand after 4 weeks without particle aggregation phenomenon; in the range of 0.05 MPa and 0.1 MPa, 1450 K and 1750 K, Al NPs can make the ignition delay of HD-01 and QC fuel shorten by about 50% and the apparent ignition activation energy reduce from 161.4 kJ·mol^-1 and 120.3 kJ·mol^-1 to 156.5 kJ·mol^-1 and 112.8 kJ·mol^-1, respectively; Inferring that the combustion mechanism as that aluminum atoms preferentially react with O₂ to produce O radicals, thereby accelerating the combustion reaction. In addition, Al NPs can completely burn and promote the energy release during fuel combustion.

Abstract:Aluminum Powder and RDX are important metal fuels and energetic oxidants in the field of solid propellants. The ignition test of nano-aluminum/RDX mixture samples at different pressures(0.1, 0.4, 0.7, 1.0 MPa and 1.3 MPa)was carried out using a medium-pressure condenser heating experimental bench. The high speed photographer, two-color infrared thermometer and fiber optic spectrometer were used to study the combustion process.Results show that there is a significant heat evaporation stage before ignition. The duration of the flame development stage is less than that of the recession stage. Increasing pressure can effectively increase the combustion strength, but too high pressure will inhibit the flame development. As the pressure increases, evaporation stage and ignition overlap and ignition delay time is shortened. Based on the experimental conditions, the ignition delay time was 1004 ms at 0.1 MPa, and the maximum temperature was 1239 ℃. At 1.3 MPa, the ignition delay time was reduced to 319.2 ms, and the maximum temperature increased to 1441℃. At 0.1 MPa, samples burn incomplete and the self-sustaining burning time is the shortest. When the pressure is higher than 0.1 MPa, the self-sustaining burning time decreases with increasing pressure.

Abstract:The fatigue properties of hydroxyl terminated polybutadiene(HTPB) propellant specimen at room temperature were studied by using infrared thermography.Based on the assumption of the limiting energy theory, a energy model of Miner′s linear cumulative damage theory was established to predict the residual life of materials.The temperature change during fatigue loading was explained by a theoretical model based on heat conduction, thermoelasic and inelastic effects. Results show that the temperature evolution in the fatigue loading process of HTPB propellant is mainly divided into three stages: initial temperature rise, temperature stabilization and temperature rise rapidly. The fatigue limit of HTPB propellant predicted by infrared thermography is 0.102 MPa and 0.113 MPa, the relative errors are 3.55% and 14.7% compared with the experimental result of 0.0985 MPa. The S-N curve obtained by the energy method is in good agreement with the S-N curve obtained by the traditional test method. Miner's energy model can accurately predict the residual life of the HTPB propellant under cyclic loading, and the relative error with the actual life is not more than 10%.

Abstract:The energy characteristics of CMDB propellant containing 2, 3-bis (hydroxymethyl)-2, 3-dinitro-1, 4-butanediol tetranitrate (DNTN) were calculated by NASA-CEA software based on the minimum free energy method. The interaction of DNTN with components of composite modified double base (CMDB) propellant was studied by differential scanning calorimetry(DSC). Results show tthat The substitution of RDX in nitrocellulose(NC)+ nitroglycerin(NG)/Hexogen(RDX)/Al propellant formulation for DNTN makes the system have the greatest theorety specific impulse, reaching 2666.5 N·s·kg^-1, the characteristic velocity increase gradually, the oxgen coefficient improve gradually. The substitution of all AP in NC+NG/AP/Al propellant formulation for DNTN makes the system have the greatest theory specific impulse, up to 2669.1 N·s·kg^-1, the average molecular weight of combustion gases decrease and the combustion temperature rise, indicating that DNTN has good application potential in CMDB propellant. There are not obvious interactions between DNTN with (NC/NG), RDX, Octogen (HMX), hexanitrohexaazaiso-wurtzitane (CL-20), carbon black (C.B) and N-nitrodihydroxyethylaminedinitrate (DINA), and there are strong interaction between DNTN with lead phthalate(φ-Pb) and 1, 3-dimethyl-1, 3-diphenylurea(C2).

Abstract:To study the effect of hydroxyl terminated polybutadiene(HTPB) propellant with initial defects on its macroscopic mechanical properties, the multi-step relaxation and uniaxial tensile tests of the home-made HTPB propellants with different content of initial interface defect were conducted and the equilibrium response curve and tensile curves of HTPB propellant were obtained. The equilibrium response curve of HTPB propellant without initial defects was fitted by Ogden model. The strain rate parameter M was introduced to discribe the rate dependence characteristics of uniaxial tension curves of HTPB propellant, and the parameters of the visco-hyperelastic constitutive model of HTPB propellant without defects were obtained through fitting the curves. The influence of initial defects was taken into consideration, the visco-hyperelastic constitutive model of HTPB propellants with initial interface defects was constructed by introducting the initial damage factor f and all model parameters were obtained by fitting step by step. Finally, the macroscopic mechanical behavior of HTPB propellant under uniaxial tension loading was predicted by the model established by this investigation. Results show that the predicted results are consistent with the experimental ones, the maximum deviation between the two is only 4.4%, which confirms the reliability of the model.

Abstract:3, 4-Bis(pyrazine-2′-y1)furoxan(BPF) was synthesized using self-synthetic 2-chloroximopyrazine as starting material via cyclization reaction. The structure of target compound BPF was characterized by the means of IR, ¹H NMR, ¹³C NMR, elemental analysis and MS. The mechanism of cyclization reaction was investigated. The synthetic conditions of cyclization reactions were optimized. The thermal decomposition mechanism of target compound was studied using a variety of thermal analysis methods just as differential scanning calorimetry(DSC) and thermogravimetric(TG-DTG). Results show that the optimum conditions of cyclizations are that diethyl ether is solvent, 3% Na₂CO₃ aqueous solution is deacidification catalyst, n_actual:n_theory (the amount of Na₂CO₃) is 1.10, reaction temperature is 2-10 ℃, reaction time is 4 h, and the yield of BPF is about 75.6%. The thermal decomposition of target compound BPF is firstly occurred at N—O bond of furoxano ring.

Abstract:By-product dinitromethane in the manufacturing process of 1, 1-diamino-2, 2-dinitroethylene(FOX-7) from 4, 6-dihydroxy-2-methylpyrimidine(MPO) was recovered, the long needle dinitromethane potassium salt(KDNM) crystal with stable property was prepared via neutralization using aqueous potassium hydroxide solution, 1, 3-dibutyl -5, 5-dinitrohexahydropyrimidine was prepared via Mannich condensation reaction using KDNM, formaldehyde and tert-butylamine as raw materials, and 1, 3, 5, 5-tetranitrohexahydropyrimidine(DNNC) was prepared via the nitrolysis of 1, 3-dibutyl -5, 5-dinitrohexahydropyrimidine with mixed acid system of concentrated sulfuric acid and concentrated nitric acid with total yield of 78.9%(Calculated by KDNM). The structure of DNNC and intermediate were characterized by ¹H NMR, IR, MS. The effect of pH value, solvents and temperature on Mannich condensation reaction, and the effect of selection of nitration system on the nitating reaction were studied. The optimal conditions of Mannich condensation reaction were determined as: the molar ratio of KDNM, formaldehyde and tert-butylamine is 1.0:3.5:2.0, 10% aqueous methanol solution is used as solvent and hydrochloric acid is used to adjust pH value to 8 at room temperature; and then temperature rises up to 50 ℃ subsequently with reaction for 3 hours, and the yield reaches 85.3%. Using mixed acid composed of 20 mL 98% H₂SO₄ and 10 mL HNO₃By as nitrolysis system, the yield reaches 92.5%.

Abstract:To investigate the influence law of particle size on the impact sensitivity of explosives in micro-and nano-scale and mechanism of action, the polymer-bonded explosives(PBXs) samples with apparent density as 1.74 g·cm^-3 and 1.50 g·cm^-3 were pressed from octogen(HMX, 100-300 nm, 1-2 μm and 10-20 μm) based PBX molding powder. The effect of HMX particle size and apparent density on the compression mechanical properties, thermal conductive properties and tablet impact sensitivity of PBX samples were studied. The micromorphology of samples before and after impact with drop hammer was observed by SEM, and the histories of force acting on samples during drop hammer impact loading were measured by a self-designed test device. Results show that the compressive strength, compressive modulus, thermal conductivity and thermal diffusivity of PBX increase dramatically with decreasing particle size of HMX. In same apparent density, the impact sensitivity of PBX decreases significantly with decrease of HMX particle size; for PBX samples with HMX of same particle size, the impact sensitivity increases slightly with the increase of apparent density. Under impact action, HMX samples with larger particle size mainly happen the pore compression and particle crack and HMX samples with smaller particle size mainly happen the shearing slip of particle layer. Under same impact condition, the peak of force acting on sample increases with increasing apparent density or decreasing particle size. Considering that the decrease of impact sensitivity caused by explosive particle refinement is the result of the combined effect of the edecrease of pore size, uniformity of pore structure, and enhancement of thermal conductivity etc. factors.

Abstract:To solve the problems of large volume and low adsorption rate of traditional adsorption equipment, the resorcinol wastewater was simulated and treated using rotating packed bed (RPB) as adsorption equipment, activated carbon as adsorbent. The effects of supergravity factor, pH value, liquid flow, temperature, and initial resorcinol concentration on the removal efficiency of resorcinol were investigated, and the adsorption isothermal equilibrium line and kinetic data were measured and the comparison with the removal efficiency of resorcinol obtained by fixed bed and magnetic strrer under approprite operating conditions were performed. Results show that the adsorption equilibrium relation mainly obeys Freundlich model, the heat of adsorption is 14.65 kJ·mol^-1. The appropriate operating conditions obtained are: liquid flow of 50 L·h^-1, supergravity factor 41.30, pH=5, temperature 20 ℃, initial concentration of wastewater of 900 mg·L^-1 and adsorption time 2 h. In this case, the removal efficiency of resorcinol reaches 96.86%. Under the same operating conditions, compared with the fixed bed and magnetic stirrers, the removal efficiency by RPB increases by about 20% and 14%, respectively. The adsorption process is mainly consistent with the pseudo-second order kinetic model. The adsorption rate constant of the adsorption process reaches 2.576×10^-3 which is 1.626 and 1.413 times higher than the conventional adsorption method of the fixed bed and magnetic stirrer, respectively.

Abstract:Zinc tri(carbohydrazide) perchlorate(GTX) is a widely-used, safe, environmental-friendly and highly-energetic primary explosive. However, excessive quantities of carbohydrazide(CHZ) and GTX are dissolved in the mother liquor during the primary explosive manufacturing processes. To maximize the elimination of the residual CHZ, the reaction process and influence factors of the reaction of sodium percarbonate(SPC) with CHZ were studied by using the volumetric titration analysis and the controlled variable method. The optimum reaction conditions under 80 ℃ are as follows: the volume ratio of CHZ (0.1 mol·L^-1) and SPC (0.15 mol·L^-1) is 1:4, the reaction time isn't less than 90 min, and the corresponding removal rate of CHZ could be as high as 68%. Moreover, the obtained reaction time and the residual CHZ concentration were fitted by the least square method based on both first-order and second-order kinetic models. Results indicate that the aforementioned reaction accords with the second-order kinetic model.

Abstract:The effects of oxygen supply and illumination, initial concentration of HMX, inoculation quantity, pH value and temperature on the degradation ability of HMX by domesticated Rhodobacter sphaeroides H strain were studied. Its kinetic equation of degradation was fitted and analyzed. The optimum conditions for the degradation of HMX by Rhodobacter sphaeroides were determined by changing one influencing factor and fixing the other four conditions. The concentration of HMX and the cell amount of Rhodobacter sphaeroides were measured by a spectrophotometer. The results show that domesticated Rhodobacter sphaeroides can efficiently degrade HMX, Rhodobacter sphaeroides H strain can grow commendably and degrade HMX under different conditions of oxygen supply and illumination, and the degradation rate reaches more than 70%. The best degradation condition is anaerobic illumination. The optimum conditions for the degradation of HMX are initial concentration of 100 mg·L^-1, pH=7, inoculation quantity of 15% and temperature of 30 ℃, the degradation rate of HMX is the highest, reaching 88.9%. The degradation process of HMX by Rhodobacter sphaeroides is consistent with the first order kinetic equation.

Abstract:2, 6-Diamino-3, 7-dis(nitroimino)-2, 4, 6, 8-tetrazabicyclo[3.3.0] octane, a new energetic compound, was synthesized from 3, 7-bis(nitroimino)-2, 4, 6, 8-tetraazabicyclo[3.3.0]octane and DppONH₂ via neutralization reaction and amination reaction. The structure of 2, 6-diamino-3, 7-dis(nitroimino)-2, 4, 6, 8-tetrazabicyclo[3.3.0] octane was characterized by infrared(IR) spectroscopy, nuclear magnetic resonance(NMR) and mass spectrometer(MS). The factors effecting the yield of target compound was investigated by orthogonal experiment. Results indicates that the yield of 2, 6-diamino-3, 7-dis(nitroimino)-2, 4, 6, 8-tetrazabicyclo[3.3.0] octane is the highest(35.07%) under the conditions of reaction time 48 h, reaction temperature 40 ℃ and 3:1 as mole ratio. The stable geometry of the compound was completely optimized at the B3LYP / 6-31G++(d, p) theoretical level of density functional theory(DFT). The theoretical density of the target compound is 1.73 g·cm^-3 by Monte-Carlo method. The heat of formation is 416.09 kJ·mol^-1 via isodesmic reaction. The detonation velocity and detonation pressure are 8.90 km·s^-1 and 34.27 GPa predicted by Kamlet-Jacobs formula. All the results show that the theoretical density, detonation velocity and detonation pressure are closed to that of RDX.

Abstract:The development of high efficiency and environmental protection type anti-infrared smokescreen has attracted wide attention at home and abroad. For this reason, all countries in the world actively develop low-toxic solid infrared extinction materials. Now metals, new carbon materials and anti-infrared composites are reported. In this paper, the research status of infrared extinction characteristics of solid aerosol particles is introduced. The research progress of the above-mentioned three kinds of materials is reviewed. It is pointed out that simulation study on extinction characteristics of aerosol particles, nano carbon materials and metal film composites are still the key research directions in the future. It is suggested that nano infrared absorbing materials, absorbing materials with one-way transparency and metallized biosome infrared absorbing materials should be actively focused on and explored. These materials are expected to become a new generation of anti-infrared materials in smokescreen. 63 references are attached.

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