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In order to investigate the absorption process of NC/Bu-NENA based propellant without NG, the formulation of NC/ Bu-NENA based propellants was designed. The absorbent was prepared under different absorption conditions such as absorption temperature, shirking ii me and cooing temperature. The dispersion of the absorbent and the politicization degree of NC molecules in the propel ant samples were studied by smooth roll calendar technology. The dispensability and legitimization degree of he absorbent were analyzed by taking high resolution image. The optimum absorption process of NC/Bu-NENA based propel ant was expired and the reasons were analyzed. The results showed that, NY, the absorption temperature sos the motet important actor in absorption process. The absorption temperature determines the diffusion rate of the plastic Bu-NENA in NC molecules. The higher the absorption temperature, he raster the diffusion rate of Bu-NENA in NC molecules, the better the plastic-Zairian. However, he higher the temperature DJs, the fatter Bu-NENA evaporates. From he equal>^um of he two, the optimal absorption temperature sos 70 . Second, the cooing temperature sos he second motet important factor in the absorption process. The cooing temperature determines he solubility of Bu-NENA in water and the degree of agglomeration of absorbent. The lower the temperature, the lower the solubility of Bu-NENA in water, the lower the degree of aggregation of absorbent. However, the temperature can not be reduced unlimited!ay in the engineering applications. By considering he two conditions, he cooing temperature should be from 20 to 25 AC . Finally, the significance of the stirring ii me sos that Bu-NENA completes the plagiarizing of NC within theses ii me period. The prolongation of firing ii me after plagiarizing has no obvious effect on improving propellant performance, and the mixing ii me should be 40--60 min. [ABSTRACT FROM AUTHOR]

in order to investigate the influence of N-butyl-N-nitratoethylnitramine (Bu-NENA) on the energy and combustion properties of NC based propellants, energy properties was theoretically calculated by Russian Real software. The propellant samples were prepared by the method of absorption-extrusion technique. The density, detonation heat, specific volume, ignition delay time, burning rate were tested and the pressure exponent were calculated. The mechanism of the influence of Bu-NENA on the combustion performance of the propellant was analyzed by combustion waves, flame photographs and morphology of flameout surface. The results showed that the replacement of NG by Bu-NENA in NC based propellant reduces energy but increases gas production. The burning rate of propellants can be significantly reduced, with the decrease of more than 75% for 2 MPa and the decrease of more than 64% for 20MPa. The pressure exponent was increased. Some catalysts used for NC/NG based propellants may fail in NC/Bu-NENA based system. The propellant ignition delay time is increased. The burning rate of the propellant is greatly reduced because of the volatilization of Bu-NENA dufing combustion and the decrease of thermal feedback caused by the decrease of combustion temperature. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) powders were fabricated by the combustion synthesis with B/KNO3/HMX (octogen) mixtures as reactants. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to investigate the phase composition and the chemical composition of the products, respectively. The morphology and resistance to oxidation were studied by scanning electron microscopy (SEM) and thermogravimetry (TGA), respectively. The characterization results showed that the h-BN which was produced through this method has high purity and exhibits excellent resistance to oxidation. The purity of h-BN is improved with the increasing content of HMX in reactants with boron carbide (B4C) and boron oxide (B2O3) as main impurity, but conversely, the yields are obviously decreased. Taking the comprehensive consideration of the purity and the yields together, the optimal molar ratio of B/KNO3/HMX is 10 : 1 : 4. In addition, the experimental results indicated that the crystalline grain size grows with the increasing content of HMX. The method explored in this study does not need expensive processing facilities and equipment, which is a preferable approach for the laboratory to prepare h-BN of high purity. [ABSTRACT FROM AUTHOR]

NO2 fission is regarded to be the most important initial decomposition process of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20). In this study, four CL-20 conformers based on the ε-CL-20 were obtained after the optimization at m062x/cc-pvtz level, and the bond length, bond order and bond dissociation energy of the N-N bonds were examined to investigate the stability of these bonds. In addition, the rate constants and activation energy of the NO2 fission were evaluated using the microcanonical variational transition state theory (μVT). The calculation results have shown that N-N bonds in the case of pseudo-equatorial and axial of nitro groups are the most stable and the least stable, respectively, by evaluating the bond length, bond order and minimum energy path (MEP). The NO2 fission rate constants are affected by not only the stability of N-N bonds but also the repulsion forces from the other nitro groups, and the fission process for pseudo-equatorial positioning of nitro groups is easier to be accelerated due to the increase of the repulsion forces. The decomposition of CL-20 conformer may mainly originate from the fission of the pseudo-equatorial positioning of nitro groups, especially for CL-20 III conformer because of the significant low activation energy. [ABSTRACT FROM AUTHOR]

Thermal reaction of paraffin with oxidizers could provide valuable information concerning the regression rate and combustion efficiency of paraffin-based fuels. In this paper, thermogravimetric–differential scanning calorimetry experiments were carried out for paraffin under O2 and N2O atmosphere, and the thermal reaction kinetics of paraffin under different pressures of O2 and N2O was estimated through the non-isothermal measurements and model-free isoconversional methods. The results show that the oxidation of paraffin under O2 and N2O atmosphere represents the multistage reaction process; the obtained activation energy (Ea) is much close by using different model-free isoconversional methods, and paraffin is easier to be oxidized under O2 because of the lower Ea and lower reaction temperature; Pressure plays a positive effect on the oxidation of paraffin, especially under O2 atmosphere. [ABSTRACT FROM AUTHOR]