对HIC试验中两种不同腐蚀介质酸碱度的探讨

HIC是腐蚀试验中常用的检测方法,用来测评材料在含硫化氢环境中对氢离子敏感性大小.其包含两种不同的腐蚀介质,不同的腐蚀介质中酸碱度是不一样的,腐蚀介质的酸碱度对试验结果有较大的影响,为此,运用电离平衡理论,计算并分析两种不同腐蚀介质电离平衡前后的氢离子浓度变化,得出动态反应平衡时氢离子浓度的关系式,从而获得介质中精确的氢离子浓度,并对腐蚀介质中相关离子进行了探讨,为进一步探究相关环境中的腐蚀机理提供了依据.     

On-line H NMR spectroscopic investigation of hydrogen bonding in supercritical and near critical CO2–methanol up to 35 MPa and 403 K

On-line NMR spectroscopy can beneficially be applied to studies of supercritical and near-critical fluids as an alternative to optical spectroscopy. Up to now high pressure NMR experiments are predominantly accomplished using custom made NMR batch reactors. The authors present a novel high pressure cell with displacement plunger for on-line NMR experiments on compressible fluids which can be used in conjunction with commercially available SCF NMR flow probes. The on-line technique offers advantages compared to stopped flow techniques such as enhanced control of mixture composition and reaction parameters as well as the facility of engagement into the reaction. The new apparatus is used for NMR studies on hydrogen bonding of methanol in near critical and supercritical carbon dioxide up to 403 K and 35 MPa for which data on the chemical shift of the hydroxyl group and methyl group are reported and interpreted.     

气相色谱在线分析变压吸附法制纯氢中的总碳

利用带镍加氢转化炉的气相色谱仪 ,在线分析变压吸附法制纯氢中的总碳。该法用变压吸附法制的纯氢作燃气 ,在检测器前端将氢气中的CO和CO2 转化为CH4,然后用氢火焰离子化检测器检测 ,直接以检测器的信号 (mV)进行定量。当氢气中总碳体积分数在 1 9～ 5 0 0 μl/L时 ,FID信号值与总碳体积分数有良好的线性关系。方法回收率为 99 90 %～ 10 1 9%,相对标准偏差 <1%。     

非化学计量LaNi5型储氢合金的性能

采用富La混合稀土与Ni、Co、Mg等元素组合，获得了一种非化学计量LaNi5型储氢合金、用金相、XRD和SEM-EDX等方法分析了该合金的组织结构，研究了合金的气相储氢特性以及电化学性能，结果表明：在1.6MPa氢压和温度29℃下，该合金的储氢量达到1.58%（质量分数），该合金的放电容量为380mAh/g。经300次循环后容量保持率为55%，该合金的基体是CaCu5型结构的LaNi5相，但有第二相（LaMg)Ni3析出，这种第二相的形成是导致该合金大容量的关键。     

Metallurgical failure analysis of cold cracking in a structural steel weldment: Revisiting a classic failure mechanism

Cold cracking of structural steel weldments is a well-characterized, well-documented, and well-understood failure mechanism. Extensive effort has been put forth to recognize the welding and materials selection parameters that are conducive to cold cracking; however, these engineering efforts have not fully eliminated the occurrence of such failures. This article describes cold cracking failure specifically related to the construction industry. This particular failure was successfully identified prior to final erection of the structural member, and the weld was successfully reworked. These actions potentially prevented a serious catastrophic event that could have occurred have occurred either later in the construction process or possibly during the use of the building. Individual welding parameters, such as electrode/wire selection, joint design, and pre/postheating, played a role in the failure, and a number of human factors relating to the actual fabrication practices also contributed to the failure process.     

Transient Green’s Tensor for a Layered Solid Half-Space With Different Interface Conditions

Pulsed ultrasonic techniques can be and have been used to examine the interface conditions of a bonded structure. To provide a theoretical basis for such testing techniques we model the structure as a layer on top of a half-space, both of different elastic properties, with various interface bonding conditions. The exact dynamic Green’s tensor for such a structure is explicitly derived from the three-dimensional equations of motion. The final solution is a series. Each term of the series corresponds to a successive arrival of a “generalized ray” and each is a definite line integral along a fixed path which can be easily computed numerically. Willis’ method is used in the derivation. A new scheme of automatic generation of the arrivals and ray paths using combinatorial analysis, along with the summation of the corresponding products of reflection coefficients is presented. A FORTRAN code is developed for computation of the Green’s tensor when both the source and the detector are located on the top surface. The Green’s tensor is then used to simulate displacements due to pulsed ultrasonic point sources of known time waveform. Results show that the interface bonding conditions have a great influence on the transient displacements. For example, when the interface bonding conditions vary, some of the first few head waves and regular reflected rays change polarities and amplitudes. This phenomenon can be used to infer the quality of the interface bond of materials in ultrasonic nondestructive evaluation. In addition the results are useful in the study of acoustic microscopy probes, coatings, and geo-exploration.     

An IR study on ion-specific and solvent-specific swelling of poly(N-vinyl-2-pyrrolidone) gel

Swelling degrees of poly(N-vinyl-2-pyrrolidone) (PVP) gel were measured in aqueous salt solutions and in water/organic solvent mixtures to find marked ion- and solvent-specificities. In order to investigate any correlation of those specificities with hydration or solvation of PVP, IR spectra band of the CO group was monitored by means of ATR method both for PVP gel and the relevant solution systems. Dependence of the peak frequency on the swelling ratio suggested that hydration of PVP carbonyl group in deswollen gel systems is different from that in the corresponding solution systems. In the solution systems, PVP carbonyl band showed a high-wavenumber shift for deswollen systems, which can be well correlated with changes in water proton charge through ionic hydration and with Gutmann's acceptor number of organic solvents. In the deswollen gel systems, the CO band showed a low-wavenumber shift, suggesting a strong hydration or doubly hydrated state. This unexpected behavior was interpreted by assuming an intermolecular hydrogen bond of two carbonyl groups intermediated by water molecules.     

加氢裂化反应器新型冷氢箱的研究与工程设计

报道了加氢加化反应器新型旋流式冷氢箱的研究设计及实用效果，催化剂床层径向温差不大于5℃。     

Electron-Impact Cross Sections for Dipole- and Spin-Allowed Excitations of Hydrogen,Helium, and Lithium

Electron-impact excitation cross sections are presented for the dipole- and spin allowed transitions from the ground states to the np ²P states for hydrogen and lithium, and to the 1snp ¹P states for helium, n = 2 through 10. Two scaling formulas developed earlier by Kim [Phys. Rev. A 64, 032713 (2001)] for plane-wave Born cross sections are used. The scaled Born cross sections are in excellent agreement with available theoretical and experimental data.     

钛及钛合金中氧和氢的联合测定

叙述了用红外吸收法对钛及钛合金中氧和氢联合测定的方法，取得了测定的最佳条件。连续测定6次的相对标准偏差在10％以下，作加标回收试验的回收率为95．6％～103．9％。分析时间在3min以内，可应用于日常分析，结果满意。