RDX和HMX的热分解III.分解机理

简述RDX和HM X热分解的各种机理,其热分解的初始过程是N-N和C-N键断裂的竞争反应,试验条件和样品相态等因素影响竞争过程。用DSC-FT IR联用技术和热裂解原位池/FT IR分析了主要分解气相产物和凝聚相中主要官能团的变化。结果表明,RDX和HM X热分解的主要分解气相产物为N2O,CH2O,CO,CO2,H2O和HCN。RDX的分解气相产物CH2O和H2O红外吸收率的温度关系曲线都产生双峰,RDX基团-NNO2的吸收带1 589 cm-1和1 278 cm-1有两个不同速率的变化过程。用N-N键和C-N键竞争断裂的观点解释了RDX与HM X热分析和产物分析的结果。     

RDX和HMX的热分解Ⅲ.分解机理

简述RDX和HMX热分解的各种机理,其热分解的初始过程是N—N和C—N键断裂的竞争反应,试验条件和样品相态等因素影响竞争过程。用DSC—FTIR联用技术和热裂解原位池／FTIR分析了主要分解气相产物和凝聚相中主要官能团的变化。结果表明,RDX和HMX热分解的主要分解气相产物为N2O,CH2O,CO,CO2,H2O和HCN。RDX的分解气相产物CH2O和H2O红外吸收率的温度关系曲线都产生双峰,RDX基团-NNO2的吸收带1589cm^-1和1278cm^-1有两个不同速率的变化过程。用N—N键和C—N键竞争断裂的观点解释了RDX与HMX热分析和产物分析的结果。     

不同热分析方法研究B炸药的热分解

用差示扫描量热仪(DSC)、热重-微熵热重分析仪(TG-DTG)、动态真空安定性技术(DVST)和温度跃升傅里叶变换红外(T-Jump/FTIR)光谱测定法对B炸药在不同试验条件下的热分解行为进行了研究。结果表明,在50～400℃有一个吸热峰和放热峰,吸热峰与主体炸药TNT的熔化峰相一致,放热峰与主体炸药RDX的分解峰一致。在50～400℃有两个失重阶段,第一个失重阶段的失重量与主体炸药TNT的失重量一致,第二个失重阶段的失重量与主体炸药RDX一致,与DSC分析结果相符。B炸药在100℃/48h下的产气量为0.43mL/g,表明B炸药有好的热安定性。B炸药快速热裂解过程的含氮气相产物主要有NO、NH3、HCN和HONO。含碳气体产物主要有CO、CO2、HOCO和HCN。得到了这些产物相对摩尔浓度随时间变化的曲线。     

高温无催化剂条件下CO还原NO数值模拟研究

随着对NOx排放标准要求越来越高,煤粉燃烧生成的NOx中NO所占比例约90％,对NO的还原研究是一项重要的课题.本文利用CHEMKIN软件的PSR模块对CO还原NO的过程进行了模拟,并对其热力学与动力学分析.结果表明:在无催化剂条件下,CO还原NO所需温度约为1650 K,压力对于反应转化率及反应路径影响不大,但对于反应速率有明显影响;反应路径分析发现,NCO自由基及N2O自由基受温度影响大,增加温度利于该两自由基生成,促进反应进行.在高温条件下,NO的还原反应不仅为CO+ NO→CO2+0.5N2还伴随2NO(=)O2+ N2反应的进行.     

RDX热分解的TG-DSC-QMS-FTIR同步动力学

采用TG-DSC-QMS-FTIR同步动力学技术对RDX的热分解过程进行了研究,结果表明,RDX在熔融之后发生分解,可以确定RDX的产物有C、H2O、CH2O、N2O、CO、CO2、NO2,可能有CH4和NH3,而几乎没有NO.采用多元非线性拟合技术进行动力学参数计算,结果表明,RDX的分解过程大致可以分为3个连续步骤,第1步反应的活化能为235 kJ/mol,指前因子log(A/s-1)为22,反应级数为0.6,主要气体产物为CO2、NO2和CH2O;第2步反应的活化能为110 kJ/mol,指前因子log(A/s-1)为1.5,反应级数为1.7,主要的气体产物是N2O、H2O、CH4、NH3、C2O+/C3H+4、CN+/C2H+3、CHO+/C2H+;第3步反应的活化能为223 kJ/mol,指前因子log(A/s-1)为20.9,反应级数为4,主要的产物是C和CO.     

冲击波加载下RDX初始反应机理及分解产物光谱特征

为了理解含能材料微观起爆机理,利用自洽电荷紧束缚密度泛函理论结合多尺度冲击模拟技术研究了固相RDX晶体在冲击波加载下的分解过程,采用含时密度泛函理论获取主要稳定产物的荧光发射谱及振动分辨的发射谱。结果表明,在低速冲击下(冲击波速度≤8km/s),温度随时间上升缓慢且达到平衡后不超过1700K,RDX未完全引爆,初始分解反应源于N—NO₂键的断裂,模拟时长超过10ps后产物随时间变化趋于稳定,最终稳定产物以NO₂、NO和H₂O为主;在高速冲击下(冲击波速度≥9km/s),平衡温度和应力显著增加,RDX完全引爆,N—NO₂键受到高压抑制,初始分解反应源于C—H键和主环上C—N键的断裂,模拟时长超过3～5ps后产物随时间变化趋于稳定,最终稳定产物以N₂、CO和H₂O为主。模拟结果反映出固相RDX在冲击作用下初始起爆过程具有显著的分段特性。CN₂分子的电子从第二激发态(E=-4007.3eV)向基态(E=-4010.8eV)跃迁,发射谱线波长...     

NH_3和ClO_3对RDX初始热裂解的影响

用B3LYP/6-31G(d)方法,优化得到RDX及其与高氯酸铵(AP)裂解产物NH3、ClO3形成复合物的稳定构型,计算了RDX及各复合物的N-NO2键解离能.结果表明,复合物中RDX构型变化不是很大,但其CS对称性遭到破坏.RDX与NH3、ClO3结合后其N-NO2键解离能与RDX相比变化不大, NH3、ClO3的存在不影响RDX硝基裂解A位优先于E位的顺序.但一旦复合物裂解,生成的NO2极易与NH3发生反应,放出大量热,从而可引发RDX的后续裂解反应.     

PYX红外热行为研究

为探讨PYX的热行为,用热裂解原位池与快速扫描红外光谱联用技术（RSC—IR）、快速升温与快速扫描红外联用技术（T—Jump RSC—IR）、热重分析与红外光谱联用技术（TG—IR）研究了PYX的热解全过程。测定了热分解过程中的凝聚相产物和气相产物,提出PYX可能的热分解机理,其热分解过程至少分两个过程：第一过程为C—NO2的异构化和-NO2与-NH基团的环化,生成NO和芳香多聚化合物;第二过程为芳香多聚化合物的分解,逸出HCN,CO,CO2,H2O等气体。     

含氮煤焦边缘模型氧化生成NO途径研究

通过Mayer键级预测反应过程,基于过渡态理论,在分子水平上研究了含吡啶氮的armchair煤焦边缘模型在燃烧过程中产生前驱体HCN以及直接与O2反应释放NO分子的全过程,并计算得到了每一步反应的反应能量和能垒大小.结果表明,含吡啶氮armchair煤焦模型化合物产生HCN的过程中N2—C4键和C1—C3键的Mayer键级最小,这两个键最先断裂后分离出HCN分子,该过程需要克服的能垒为451.671 kJ/mol,而用相同模型与O2直接氧化产生NO的过程中,C1—N2的Mayer键级最小,中间体M1需要克服259.81 kJ/mol的能垒形成中间体M2,中间体M2需要克服133.1 kJ/mol的能垒,并最终析出NO分子.对上述两过程进行能量对比发现,所选模型与O2直接发生异相反应释放NO气体的过程更容易发生.     

碳热还原氮化法制备碳氮化钛粉末

以物质的量比为1∶2.5的TiO_2粉和活性炭粉为原料,于N2气氛下采用碳热还原氮化法在不同的合成温度(分别为1500℃、1600℃、1650℃、1700℃、1750℃,N2压力固定为0.1MPa)和N2压力(分别为0.05MPa、0.1MPa、0.15MPa、0.2MPa,温度1700℃)下保温3h合成了碳氮化钛粉末。研究结果表明提高合成温度和降低N2压力有利于合成碳含量高的碳氮化钛粉末;在N2压力为0.1MPa的条件下,于1700℃保温3h热处理后,可以获得平均粒径为2μm的碳氮化钛粉末。     

[Co(CHZ)3](ClO4)2的快速热分解过程研究

通过TG、DSC等热分析技术可以得到物质在常规热分解过程的主要固相产物.为了进一步考察[Co(CHZ)3](ClO4)2(CoCP)的热分解行为,采用T-jump/FT-IR在线分析技术测定了CoCP的快速热分解气体产物.CoCP在1 atm下以一定的升温速率达到设定的温度进行快速热分解.利用其快速热分解过程的控制电压变化曲线,可以得知CoCP在快速热分解过程的吸热、放热变化情况;用快速扫描傅立叶变换红外,可以解析分解过程中逸出的12种红外活性气体.研究发现,在CoCP快速热分解过程所产生的12种气相产物中,以CO的浓度最高,NO和HCN为主要的含氮气相产物,含碳气相产物以CO,CO2和H2C=O为主;并给出了其主要气相产物的浓度随时间的变化曲线.     

RDX flame structure at atmospheric pressure

The chemical structure of an RDX flame at a pressure of 1 atm was studied using probing molecular beam mass spectrometry. The flame was found to contain RDX vapor, and its concentration profile was measured in a narrow zone adjacent to the burning surface. In addition to RDX vapor, ten more species were identified (H₂, H₂O, HCN, N₂, CO, CH₂O, NO, N₂O, CO₂ and NO₂), and their concentration profiles were measured. Two main chemical-reaction zones were found in the RDX flame. In the first, narrow, zone 0.15 mm wide adjacent to the burning surface, decomposition of RDX vapor and the reaction of NO₂, N₂O, and CH₂O with the formation of HCN and NO occur. In the second, wide, zone 0.85 mm wide, HCN is oxidized by NO to form the final combustion products. The composition of the final combustion products was analyzed from an energetic point of view. The measured composition of the products near the burning surface was used to determine the global reaction of RDX gasification at a pressure of 1 atm. Values of heat release in the condensed-phase calculated by the global gasification reaction and by the equation of heat balance on the burning surface (using data of microthermocouple measurements) were analyzed and compared. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 1, pp. 49–62, January–February, 2008.     

溶胶-凝胶法制备RDX/AlOOH

以氯化铝为前驱物,N,N-二甲基甲酰胺为AlCl3.6H2O和RDX的溶剂,1,2-环氧丙烷为胶凝剂,常温常压下,采用溶胶-凝胶法制备RDX/AlOOH复合炸药,产物用超临界流体干燥后得固体粉末。用扫描电镜和DSC研究了复合炸药的形貌分析和热分解特性。测试了复合炸药的撞击感度、摩擦感度。结果表明,溶胶-凝胶法与超临界流体干燥技术相结合,可以较好地保持凝胶的多孔结构;其热分解过程不同于物理掺杂的混合炸药,DSC曲线上熔化吸热峰几近消失,RDX/AlOOH复合炸药的撞击感度和摩擦感度均较低。     

Thermal Decomposition of Energetic Materials XXVIII. Predictions and results for nitramines of bis-imidazolidinedione: DINGU,TNGU and TDCD

Structural/thermal decomposition relationships are assessed in this project. The relative concentrations of the first observed, infrared-active gas products generated by fast thermolysis (dT/dt = 110 K/s) of 2,5-dioxo-1,3,4,6-tetranitro-tetrahydrocyclobutan[1,2-d : 3,4-d′]diimidazole (TDCD) and 1,3,4,6-tetranitroglycoluril (TNGU) were successfully predictable from structure/thermal decomposition relationships. The predictions for 1,4-dinitroglycoluril (DINGU) were only partly successful. The departures from expection appear to originate from the different degree of stability of the non-energetic backbone of these molecules. The dependence of the first-observed gas products on pressure from these molecules was qualitatively predicted from the nature of the products liberated at atmospheric pressure.     

Thermal Decomposition of Energetic Materials 83. Comparison of the Pyrolysis of Energetic Materials in Air versus Argon

T‐Jump/FTIR spectroscopy was employed to flash pyrolyze a series of energetic compounds in an air atmosphere for comparison with an argon atmosphere. The O‐NO₂ compounds (NG, NC, and PETN), N‐NO₂ compounds (RDX and HMX), and C‐NO₂ compounds (DNT, TNT, and NTO) were studied. The effect of the surrounding atmosphere on the pyrolysis gases roughly correlates with the trend in the vapor pressure of the parent energetic material (i. e. DNT>NG>TNT>NTO>PETN≈RDX>NC≈HMX). For high vapor pressure compounds, the gaseous phase reactions dominate and the dependence on the surrounding atmosphere is strong. For low vapor pressure compounds, the condensed phase decomposition dominates and the dependence on the surrounding atmosphere is weak. That is, the extent of condensed phase vs. gas phase decomposition is the major factor in the effect of the surrounding atmosphere on the decomposition gases. The main reactions in the air are CO with O₂ which is fast, and NO with O₂, which is slow. However, these pyrolysis products for the nitrate esters, the nitramines, and the C‐NO₂ compounds behave differently suggesting that a common process, such as surface catalysis, is not responsible for the behavior seen. There is little effect of the relative humidity (0–60% range) except in the case of HMX.