It is well known that imidazoles, possessing two or more nitro substituents, are potential candidates for highly energetic explosives with detonation parameters comparable to those of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane. 4,4',5,5'-Tetranitro-2,2'-bi-imidazole (TNBI) is a typical imidazole explosive with energy equivalent to that of RDX but suffers from low sensitivity (impact sensitivity 7 J). 1,1'-Diamino-4,4',5,5'-tetranitro-2,2'-biimidazole (DATNBI), a derivative of TNBI, possesses two -NH2 groups and has a higher detonation velocity (9063 m s-1) and lower impact sensitivity of 15 J, which indicates great potential for future applications. Examination of the thermal decomposition mechanism and kinetics of TNBI and DATNBI gives a more comprehensive view of the influence that the -NH2 group has on the sensitivity and storage safety of the energetic explosive-based TNBI molecular skeleton. Herein, the thermal decomposition mechanism is studied, showing that detachment of -NH2 groups from DATNBI generates 1-diamino-4,4',5,5'-tetranitro-2,2'-biimidazole (ATNBI) and TNBI and induces self-decomposition. Although the decomposition peak temperature of DATNBI is significantly lower than that of TNBI at the same heating rate; its self-accelerating decomposition temperature (50 kg) is only 4 K lower. Therefore, the -NH2 group displays good ability of reducing sensitivity but has no influence on storage safety of DATNBI.

The bistetrazole N-oxide energetic ionic salt dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) has attracted great interest as it breaks through the limitations of the traditional nitro group, high detonation velocity and moderate impact sensitivity. Reports show that TKX-50 transforms into the 5,5'-bis(2-hydroxytetrazole) (BTO) precursor, which is further decomposed and partly converted to diamino 5,5'-bistetrazole-1,1'-diolate (ABTOX). Studying the effects of H+, NH3OH+ and NH4+ on the thermal decomposition mechanism of bistetrazole N-oxide anion would provide a more comprehensive understanding of the TKX-50 decomposition mechanism. Herein, TKX-50, BTO and ABTOX decomposition rates, on-line analysis of the gas products, as well as quantitative analysis, are presented. It was found that the presence of two H+ decreases the decomposition temperature, whereas NH3OH+ greatly increases the decomposition rate. In the presence of NH3OH+, the bistetrazole N-oxide anion completely decomposes without producing C2N2; however, NH4+ promotes the polymerization of C2N2 generated by the bistetrazole N-oxide anion, and the amount of NO produced is greater than that of N2O. Therefore, in the TKX-50 decomposition process, the bistetrazole N-oxide anion does not receive two H+ simultaneously and converts into BTO. Furthermore, the competition between cations and their decomposition products for the H+ affects the degree of decomposition, which is important in understanding the energy release mechanism.

5,5'-Bitetrazole-1,1'-dioxydihydroxylamine salt (TKX-50), a high-energy energetic material, possesses good safety and energy properties. The energy characteristic data of TKX-50 are commonly generated via theoretical simulation and experimental measurements. Interestingly, the detonation velocity of TKX-50 is higher than HMX, but the specific kinetic energy of TKX-50 is the opposite. Thus, a systematic study on the decomposition mechanism of TKX-50 is important to establish the reasons for this variation in specific kinetic energy. Although the thermal decomposition mechanism of TKX-50 has been reported, the specific compositional changes of its gas products under different heating conditions remain unknown, hindering a comprehensive understanding of the mechanism from the perspective of gas products. Herein, the gas products of TKX-50 and HMX in thermal decomposition and thermal explosion are investigated and compared. It was found that more TKX-50 is converted to ABTOX for further decomposition when the heating rate increases. ABTOX can decompose to C2N2, which is prone to polymerization, generating a solid residue under high temperature and pressure. Although polymerized C2N2 decomposes and burns during the explosion, it delays the time of TKX-50 reaching its maximum amount of outgassing, thereby affecting its specific kinetic energy. Furthermore, in the thermal explosion, compared with HMX, TKX-50 generates less H2 and CO. Since the combustion heat of hydrogen is much higher than that of carbon, the more hydrogen generated, the higher the detonation heat obtained. Therefore, TKX-50 has a lower detonation heat, which also affects its specific kinetic energy.

为探索SnSe2二维薄膜材料的气敏特性,采用分子力场方法系统地研究了SnSe2二维单层材料对H2,CO,NH3及NO2等4种典型气体分子的最优吸附位置和吸附能力,并基于密度泛函理论(DFT)的第一性原理方法计算了吸附前后的键长键角变化率、能带结构、态密度及电荷差分密度等参数,分析了吸附前后的电子结构变化与气敏效应之间的内在关联.计算结果发现,吸附H2和CO未能对SnSe2单层的能带结构和电子结构产生改变,而NO2和NH3却在导带底(CBM)和价带顶(VBM)之间分别产生了新的杂质能级,并使费米能级发生位移,从而改变SnSe2单层电子结构.电荷差分密度分析进一步表明SnSe2二维单层未能对H2和CO产生响应,而对NH3和NO2却有明显的气敏效应,其中对NO2有良好的敏感性能和选择性.

Bistetrazole energetic ionic salts, such as dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) and diamino 5,5'-bistetrazole-1,1'diolate (ABTOX), are new insensitive materials and have great potential applications because of their good energy and safety performance. Prior to pure explosive preparation into PBX, the interactions between the components must be evaluated. Examination of interactions between bistetrazole ionic salt and ammonium nitrate explosive in thermal decomposition is beneficial in revealing the interactive mechanism of these two kinds of energetic materials in decomposition, as well as in the evaluation of compatibility, safety, and reliability of PBX explosive based on TKX-50, ABTOX, HMX, and RDX. Herein, the thermal decomposition behavior of TKX-50/HMX, ABTOX/HMX, TKX-50/RDX, and ABTOX/RDX is investigated. Ammonium nitrate explosives can significantly reduce the thermal decomposition peak temperature of the bistetrazole ionic salt. For example, HMX reduces the decomposition peak temperatures of the first and second stages of TKX-50 by 4 and 15 K, respectively, and ABTOX by 26 K (heating rate 5 K min(-1)). Utilizing HMX, the interaction mechanism between ammonium nitrate explosives and bistetrazole ionic material in thermal decomposition was investigated in detail. Changes in gas products, morphology, and molecular structure of the materials during decomposition show that TKX-50 induces HMX to HONO elimination decomposition, while ABTOX induces HMX open-loop decomposition. Furthermore, the heat generated by HMX decomposition accelerates the decomposition of TKX-50 and ABTOX. Moreover, the melting characteristics of HMX and molten product formation in the decomposition of TKX-50 and ABTOX promote the interaction between solid phase materials. Additionally, using calculation simulation, we confirmed that NH3OH+ in TKX-50 transfers hydrogen to the HMX nitro group, resulting in the HONO elimination of HMX, while the bistetrazole N-oxide anion in ABTOX and its alkaline decomposition intermediate product captures the hydrogen of the HMX main ring and causes HMX ring-opening decomposition.

湿度传感器与大气监测、工业生产和生物医疗等领域息息相关.随着科技的不断发展,人们对高性能湿度传感器的需求不断增加,这为湿度传感器行业的发展带来了前所未有的机遇和挑战,其中高性能湿敏材料的开发尤为关键.在诸多湿度传感器中,金属氧化物或金属氧化物/聚合物复合材料湿度传感器因其敏感元件选择的多样性、易于后加工处理和响应特性高等特点而受到广泛关注.与聚合物湿度传感器相比,陶瓷材料的合成过程更简便,响应也通常更为迅速,且聚合物的成本更低.近些年,新型纳米材料被广泛应用于湿度传感器领域,逐渐成为湿敏材料的主要发展方向及研究热点.零维和一维纳米碳质材料,如富勒烯、碳纳米管作为湿敏活性层制备的传感器通常具有大比表面积、可室温下工作、易于实现微型化、稳定性好等诸多优点,但它们的零维或一维结构与现有的平面电子器件加工工艺不相匹配.石墨烯是由sp2杂化的碳原子紧密排列构成的二维蜂巢晶格结构的单层石墨,其独特的二维结构适用于现有的平面电子器件加工工艺.石墨烯材料作为湿敏活性层受到研究者们的广泛关注是因为它具备诸多优异特性:(1)石墨烯的所有原子都在表面,具有超大的比表面积,原则上,石墨烯传感器的动态检测范围可以从单个分子到很高的浓度水平;(2)利用石墨烯的电学特性和力学特性可以很好地进行传感信号的转换;(3)金属、聚合物或其他修饰剂功能化的石墨烯能与特定分子发生相互作用,大大增强传感器的选择性;(4)石墨烯单晶可以制作四探针装置,从而能够避免接触电阻的影响,并大大提高灵敏度;(5)与其他纳米碳材料如碳纳米管相比,石墨烯和氧化石墨烯制备成本更低.本文综述了石墨烯湿敏性能及其应用的研究进展,着重讨论了本征石墨烯、氧化石墨烯和改性石墨烯的湿敏特性.文章最后分析了石墨烯基湿度传感器未来的发展方向和面临的挑战.

In this work, a PdNi thin film hydrogen gas sensor with integrated Pt thin film temperature sensor was designed and fabricated using the micro-electro-mechanical system (MEMS) process. The integrated sensors consist of two resistors: the former, based on Pt film, is used as a temperature sensor, while the latter had the function of hydrogen sensing and is based on PdNi alloy film. The temperature coefficient of resistance (TCR) in both devices was measured and the output response of the PdNi film hydrogen sensor was calibrated based on the temperature acquired by the Pt temperature sensor. The SiN layer was deposited on top of Pt film to inhibit the hydrogen diffusion and reduce consequent disturbance on temperature measurement. The TCR of the PdNi film and the Pt film was about 0.00122/K and 0.00217/K, respectively. The performances of the PdNi film hydrogen sensor were investigated with hydrogen concentrations from 0.3% to 3% on different temperatures from 294.7 to 302.2 K. With the measured temperature of the Pt resistor and the TCR of the PdNi film, the impact of the temperature on the performances of the PdNi film hydrogen sensor was reduced. The output response, response time and recovery time of the PdNi film hydrogen sensors under the hydrogen concentration of 0.5%, 1.0%, 1.5% and 2.0% were measured at 313 K. The output response of the PdNi thin film hydrogen sensors increased with increasing hydrogen concentration while the response time and recovery time decreased. A cycling test between pure nitrogen and 3% hydrogen concentration was performed at 313 K and PdNi thin film hydrogen sensor demonstrated great repeatability in the cycling test.

This paper reports a novel prototype of hydrogen sensing device with micro size, low power cost and low operating temperature. The sensor integrated sensing and heating function was fabricated with the process of bulk-Si MEMS. Two classic materials doped Pd, SnO2 and MnO2, were spun coating on inter-digital electrode device for detecting the hydrogen with various magnitude from 10ppm to10000ppm. Different tendency of sensing response in ambient of oxygen is due to variation of charge carrier in semiconductor.

有一定规模的化工科研生产单位都需要使用大量的化学溶试剂,并且建有专门的危化品库房,为方便使用,许多基层单位往往把领用的化学溶试剂暂存在暂存间内,如不妥善管理,必然造成安全隐患.本文从本单位实际出发,根据有关安全规范,从存量控制、物理环境和管理物理环境等方面进行了安全管理探讨,并提出了相应的管理改进措施.

本文依据葡萄糖在水热条件下可生成模板剂胶体碳球的原理,以葡萄糖和六水合氯化钴为原料,经180℃条件下的水热反应,然后进行热处理制备了纳米四氧化三钴空心球材料.采用X射线粉末衍射仪对产物进行了结构表征,实验表明所得四氧化三钴的晶形为面心立方结构.采用热场发射扫描电镜对产物进行了形貌分析,实验表明所得四氧化三钴的形貌为空心球,空心球的直径约为0.3~1.2μm,球壳为多孔结构.分析了水热反应时间对四氧化三钴空心结构的影响.试验证明,将水热反应从2小时延长到4小时时,产物的形貌基本保持不变.

Studies on crystalline morphology,crystallization kinetic and thermodynamic of the eutectic are reviewed,and the factors that influence the crystallization behavior of the eutectic are emphasized.It reveals that theoretical calculation together with experiment to obtain the relationship between crystallization behavior and thermal stability,sensitivity is the trend for future development,and establish a new crystallization kinetics model and method in this field are the research emphasises.

对聚醚多元醇酸值测定结果的不确定度进行了评估,找到了影响测试结果的重要因素为滴定聚醚多元醇时消耗NaOH的体积.通过实验对该分析方法进行了改进,改进后的方法合成不确定度仅为0.0028mgKOH/g.实践证明,不确定度评定是改进分析方法的重要手段之一.

对GB12008.5-1989标准中聚醚多元醇酸值测定中称样量、允差、溶剂3个方面的问题进行了探讨,并对存在的问题提出了改进办法。

Fluoropolymers F2311 and F2314 samples were irradiated by neutrons of 1.23 MeV in average energy up to fluences of 1.5×1013 / cm2 and 2.5×1013 / cm2, and their static and dynamic mechanical properties and molecular weight were determined. It indicated that static mechanical properties of the F2311 samples and tensile intensity of the F2314 samples increased with the neutron fluence, whereas compression intensity of the F2314 samples decreased with the neutron fluence. Molecular weight of both the fluoropolymers increased with the neutron fluence. Little changes were found with dynamical properties of the F2311 samples, whereas dynamical properties of the F2314 samples de- creased with the neutron fluence.

2,3,5,6-Tetrachloro-4-methylsulfonylpyridine are identified by gas chromatography-mass spectrometry (GC/MS); The fragment routes of characteristic are discussed on the basis of EI mass spectra. The characteristic of the compound is of C-S bonds fragmentation of sulphonyl groups, C-Cl bonds and O-C bonds fragmentation accompanied by hydrogen migration of methyl sulphonyl groups. The full scan MS2 spectra of fragment m/z 231 is obtained by ion trap mass spectrometry in a multi-stage tandem MS full scan mode. The characteristic fragments of m/z 231 are used to prove the structure of m/z 231.

Gases released by accelerated aging JOB-9003 molding powder and pellets at different temperatures for 2～4 months and the effect of storage conditions on the amount of gases are studied by means of SPME, GC and GC-MS techniques. The results showed that variety of gases such as toluene, ethyl acetate, 2,4,6-trinitrotoluene(TNT), 2-chloropropanonitrile and so on could be examined, which derived from raw materials and solvents used in making ingredients between gases released by JOB-9003. The amount of gases increased with the increase of accelerated aging temperature and time.

采用元素分析仪测定炸药中的碳(C)氢(H)氮(N)百分含量,讨论了测试过程中由测量重复性、称量过程等因素所带来的不确定度分量,计算了测定炸药中的C、H、N百分含量的合成标准不确定度及扩展不确定度,确定采用元素分析仪测定奥克托金(HMX)的C,H,N含量的扩展不确定度小于0.5%.