Research on thermal decomposition of trinitrophloroglucinol salts by DSC, TG and DVST

The thermal decomposition of the four nitrogen-rich salts of ammonia (NH₄), aminoguanidine (AG), carbohydrazide (CHZ) and 5-aminotetrazo (ATZ) based on trinitrophloroglucinol (H₃TNPG) was investigated using the differential scanning calorimetry (DSC), thermogravity (TG), and dynamic vacuum stability test (DVST). DSC and TG methods research the complete decomposition, while DVST method researches the very early reaction stage. The peak temperatures of DSC curves are consistent with the temperatures of maximum mass loss rates of TG curves. The apparent activation energies of these H₃TNPG-based salts obtained by DSC and DVST have the same regularity, i.e., (ATZ)(H₂TNPG)·2H₂O < (CHZ)(HTNPG)·0.5H₂O < NH₄(H₂TNPG) < (AG)(H₂TNPG). The thermal stability order is (ATZ)(H₂TNPG)·2H₂O < (CHZ)(HTNPG)·0.5H₂O < (AG)(H₂TNPG) < NH₄(H₂TNPG), which was evaluated by DVST according to the evolved gas amount of thermal decomposition. DVST can monitor the real-time temperature and pressure changes caused by thermal decomposition, dehydration, phase transition and secondary reaction, and also evaluate the thermal stability and kinetics.      

Thermal stability and sensitivity of RDX-based aluminized explosives

The thermal decomposition characteristics and thermal sensitivity are key indicators for reflecting the thermal stability of explosives in storage and application. The thermal decompositions in different degrees are used to determine the dominant factor which controls the thermal stability of composite explosive. Four kinds of RDX-based aluminized explosives are marked as RA1, RA2, RA3, and RA4 with the Al content increasing from 10 to 40 mass%. The initial thermal decomposition behaviors were studied by DPTA and the complete thermal decompositions were studied by DSC and TG. The thermal sensitivities were characterized by 5-s explosion point. The effects of micron-sized Al particles and their contents on thermal decomposition were investigated. The evolved gas amount (V _i) from DPTA test follows RA3 < RA4 < RA2 < RA1, indicating that RA3 has the best thermal stability at ambient storage conditions. However, according to TG and DSC tests, the characteristic temperatures of thermal decomposition (T _p, T _b, and T _SADT), the thermodynamic parameters (?H _e, ?S ^≠, and ?H ^≠), the kinetic parameters (E _a and A), and the 5-s explosion points all follow RA4 < RA3 < RA2 < RA1. The results indicate that the Al particles play different roles in the different degrees of thermal decomposition. In the initial decomposition, the Al particles have not been activated and are considered as inert materials that hinder the decomposition of explosive. In the complete decomposition, the Al particles catalyze the thermal decomposition, and such catalysis becomes more obvious as the Al content increases to a certain degree.     

含能配合物[Zn(CHZ)3](C1O4)2的晶体结构、热行为及感度性能研究

通过碳酰肼水溶液与高氯酸锌水溶液反应制得含能配合物[zn(cHZ)3](CIO4)2.培养获得了配合物的单晶,用x射线单晶衍射法测定了晶体结构,该晶体属于单斜晶系、P2(1)/n空间群,晶胞参数a=1.0005(2)nm,b=0.8428(1)nm,c=2.1218(4)nm,β=100.948(3)°,y=1.756...     

硝基四唑及其高氮化合物*

硝基四唑及其高氮化合物是指分子中含有5-硝基四唑结构的一类高氮化合物,优越的性能和突出的特点使其成为含能材料领域的研究热点之一,在起爆药、推进剂及其燃速催化剂、高能炸药、气体发生剂等领域有着广泛的应用前景。本文对硝基四唑的结构与热分解机理进行了分析介绍;全面系统地综述评价了硝基四唑及其盐类和配合物类衍生物的合成、性能表征与应用前景。根据其成盐阳离子的不同,硝基四唑盐类主要包括碱金属盐、碱土金属盐、过渡金属盐、胺盐和高氮杂环阳离子盐。根据配位方式的不同,其配合物可分为配阴离子型和配阳离子型。在此基础上,对硝基四唑及其高氮化合物的未来发展及应用提出了展望。     

柱前衍生高效液相色谱法测量碳酰肼的含量

建立了苯甲醛衍生测量碳酰肼产品纯度的高效液相色谱法。研究了流动相中pH值、流动相组成、衍生反应时间等因素对测定的影响。采用KromasilC18(250mm×4.6mm,5μm)色谱柱,流动相为乙腈5mmol/L磷酸盐缓冲溶液,流速1mL/min,检测波长310nm,在8min内可完成分析。碳酰肼与苯甲醛在室温下衍生30min后可直接测量。此方法操作简单、快速;方法检出限为0.13mg/L;回收率为105%;RSD<1%,用于碳酰肼产品的纯度分析,结果令人满意。     

Direct synthesis, crystal structure and thermal analyses of 2-nitroterephthalate and carbohydrazide bridged staircase-like 3D packing grids of lead(II)

X-ray single crystal diffraction demonstrates that in {[Pb₂(HNTP)₂(NTP)(CHZ)(H₂O)₂] · 2.5H₂O} _n (polymer, NTP = nitroterephthalate, CHZ = carbohydrazide), there are two kinds of Pb centers. By means of the bridging ligands–two water, two CHZ and two NTP molecules, four Pb centers (two Pb1 and two Pb2) are joined together to form the rectangular grid, and by the intense static electric interactions among the two O atoms of nitro groups in NTP, the extending two-dimensional grids are linked together to form the three-dimensional frameworks. Thermal analyses DSC and TG-DTG have been performed on the polymer to study its thermal decomposition mechanism and thermal kinetic properties. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Enhanced strain relaxation induced by epitaxial layer growth mode of MgO thin films

Growth of MgO films on silicon substrate was conducted by KrF excimer pulsed-laser ablation system. Two kinds of growth mode were revealed in situ by reflection high energy electron diffraction. It was found that the layer growth mode of MgO thin films could remarkably reduce the misfit strain originated from the different lattice constant and thermal expansion coefficiency between MgO films and Si. An enhanced strain relaxation was discovered for MgO films, which were grown with the layer growth mode, in the film thickness range of 40-100 nm. The value of critical thickness for the formation of misfit dislocation agrees well with the calculated one. This exceptional phenomenon should be ascribed to the layer growth mode of epitaxial MgO films.     

Synthesis and Structure Investigation of a Novel 3-Dimensional Potassium Supermolecular Compound Based on 2,4-Dinitro Resorcinol

A novel 3‐dimensional potassium supermolecular compound [K(HDNR)(H₂DNR)(H₂O)]_n (H₂DNR?2,4‐dinitro resorcinol) was synthesized and characterized by elemental analysis and FT‐IR spectroscopy. The crystal structure investigated by X‐ray single crystal diffraction shows that [K(HDNR)(H₂DNR)(H₂O)]_n crystallizes with a monoclinic unit cell in the space group P2(1)/c with unit cell dimensions of a=17.648(5) Å, b=12.527(3) Å, c=7.735(2) Å, β=94.33(2)°, V=1705.00(73) ų, Z=4. The structure was refined to the final R=0.0670 and wR=0.0722 for 2022 observed reflections with I>2σ(I). In the compound, potassium cation is assembled into one‐dimensional chains along c‐axis through oxygen atoms from water molecules, and the chains were connected by the bridged HDNR^? anions to form a two‐dimensional net structure. The two‐dimensional nets constructed a three‐dimensional supramolecular architecture via intermolecular hydrogen bonds and N–O···π interaction. Density functional theory (DFT) B3LYP was employed to optimize the structure and calculate energies for three tautomers of HDNR^? univalent anion. Three stable tautomers were located. It was found that the structure (I) with O(1) losing hydrogen atom is more stable than the structure (II) also with O(1) losing hydrogen atom and the structure (III) with O(4) losing hydrogen atom.     

The crystal and computed structures of 1,2,4‐triazol‐5‐one (TO)

1,2,4‐Triazol‐5‐one (TO) was synthesized by reacting semicarbazide hydrochloride with formic acid and its single crystal was grown by the slow evaporation method. Its molecular structure and crystal structure were determined by X‐ray single crystal diffraction technique. The obtained results show that the crystal belongs to Crystal system of Monoclinic, space group Pn. It was characterized by elemental microanalysis and FT‐IR techniques. Based on the crystal data, we had also carried quantum chemistry calculations on the title compound using the B3LYP and MP2 method with cc‐pVTZ basis set. The calculation results further demonstrate the crystal structure of title compound and its other related properties.     

基于混合网格Navier-Stokes方程的并行隐式计算方法研究

针对结构网格很难处理复杂外形和非结构网格无法计算具有边界层的粘性流动的缺点,发展了基于混合网格格点的隐式算法,成功地解决了在工程应用中难于处理的复杂外形粘性流场计算和效率问题。同时针对大规模的工程问题,发展了基于MPI通信技术的染色分层通讯并行计算方法。其中空间离散采用基于Roe格式发展的三阶迎风HLLEW(Harten-Lax-Van Leer-Einfeldt-Wada)或AUSM格式,湍流模型采用k??两方程湍流模型,时间推进考虑到LU-SGS并行等效较困难则采用基于DP-LUR(Data-Parallel Lower-Upper Relaxation)格式的隐式算法,计算CFL数可取到105量级,从2个到128个CPU的并行加速效率都保持在90%以上,大大提高了计算效率。算例对标模M6机翼模型流场进行计算,验证了方法的可靠性;然后对标模DLR-F6翼身组合体进行混合网格粘性与无粘计算结果进行比较,进一步验证混合网格方法;最后计算了DLR-WBNP外挂发动机翼身组合体模型,准确模拟了外挂和超临界机翼的相互干扰流动问题,采用4 CPU 16 CORE到24 CPU 96 CORE,2000步计算时间都不超...