Nickel interlayer on the microstructure and property of TC6 to copper alloy diffusion bonding

In the present study, diffusion bonding of two dissimilar materials TC6 and copper alloy was investigated in vacuum chamber by directly bonding and using Ni foil as interlayer. Interface quality of the joints was evaluated by mechanical property and microstructure. The maximum shear strength of directly bonding was found to be 64 MPa for the speciemen bonded at 850 °C, 5 MPa for 30 min; and the maximum shear strength with Ni foil interlayer was 113 MPa under the same bonding parameters. The bonding interfaces and fracture surfaces were analyzed by energy disperse spectrometer, scanning electron microscopy and X-ray diffraction. The results show that the diffusion region of directly bonding specimen generated several IMCs (Ti₂Cu and Ti₅CuSn₃, etc.). Fracture morphology showed that brittle fracture present at the Ti₅CuSn₃ IMCs, which was the weak point of the joint. While the diffusion zone of the specimen with Ni foil interlayer consists of various phase including Ti₂Ni, TiNi, TiNi₃ at TC6 side, and Cu-Ni solid solution at ZQSn11-4-3 side, and fracture surface of joint present a mixture of brittle and ductile characteristics, and fracture initiated at the TiNi₃/Ni interface.     

FTIR 发射/透射光谱对含颗粒气流的温度测量

在改进的FTIR和自制的微量给粉加热／燃烧实验装置上，对粘土颗粒气流和煤粉火焰进行了FTIR发射／透射测量。通过发射／透射光谱可以得到颗粒温度和气体温度，其相对误差小于5%，满足实验室和工业测温要求。当被测样品中存在碳黑和其它颗粒时，基于碳黑的吸收特性，给出了消除碳黑辐射影响的一种近似处理方法，即将吸收光谱外推至0cm^-1，以0cm^-1处的数值为准对整个光谱进行校正，所得光谱就认为是去除碳黑影响后的吸收光谱．对于CO2气体温度，研究表明，可以用通过CO2峰值的黑体理论曲线来简单估计．研究还发现炭粒温度可以高出气体温度200—300K，一个可能的原因是CO在颗粒边界层点燃引起了颗粒温度突然升高并高于气体温度，对这种现象的理论解释和更多的实验验证尚需进一步展开。     

Two-Variable Refined Plate Theory for Thermoelastic Bending Analysis of Functionally Graded Sandwich Plates

The thermoelastic bending analysis of functionally graded sandwich plates using the two-variable refined plate theory is presented in this paper. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The sandwich plate faces are assumed to have isotropic, two-constituent material distribution through the thickness, and the modulus of elasticity, Poisson's ratio of the faces, and thermal expansion coefficients are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. Several kinds of sandwich plates are used taking into account the symmetry of the plate and the thickness of each layer. The influences played by the transverse shear deformation, thermal load, plate aspect ratio, and volume fraction distribution are studied. Numerical results for deflections and stresses of functionally graded metal–ceramic plates are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of functionally graded plates.     

The role of oxygen vacancies in the CO2 methanation employing Ni/ZrO2 doped with Ca

The Ni/ZrO₂ catalyst doped with Ca and Ni/ZrO₂ were employed in the CO₂ methanation, a reaction which will possibly be used for storing intermittent energy in the future. The catalysts were characterized by X-ray photoelectron spectroscopy (XPS, reduction in situ), X-ray diffraction (XRD, reduction in situ and Rietveld refinement), electron paramagnetic resonance (EPR), temperature-programmed surface reaction, cyclohexane dehydrogenation model reaction, temperature-programmed desorption of CO₂ and chemical analysis. The catalytic behavior of these catalysts in the CO₂ methanation was analyzed employing a conventional catalytic test. Adding Ca to Ni/ZrO₂, the metallic surface area did not change whereas the CO₂ consumption rate almost tripled. The XRD, XPS and EPR analyses showed that Ca⁺² but also some Ni²⁺ are on the ZrO₂ surface lattice of the Ni/CaZrO₂ catalyst. These cations form pairs which are composed of oxygen vacancies and coordinatively unsaturated sites (cus). By increasing the number of these pairs, the CO₂ methanation rate increases. Moreover, the number of active sites of the CO₂ methanation rate limiting step (CO and/or formate species decomposition, rls) is enhanced as well, showing that the rls occurs on the vacancies-cus sites pairs.     

夹层板的稳定性分析方程

本文用Reissner理论构造了一种八节点等参单元，对于表层较薄、夹芯剪切模量较大的复合材料夹层板，提供了一种相对简单的有限元计算方法。给出了详细的理论推导，分析了材料性质参数和板的几何参数变化的情况下，夹层板的稳定性情况，为实际的结构设计提供参考依据。     

Voltammetric studies of gold surface modified by bis(octakis(octyloxy) phthalocyaninato) europium(III) adlayers in perchloric acid solution

Bis(octakis(octyloxy) phthalocyaninato) europium(III) (Eu[Pc(OC₈H₁₇)₈]₂) adlayers were self-assembled on the gold surface by means of an improved self-assembling technique. The cyclic voltammograms (CVs) of the Eu[Pc(OC₈H₁₇)₈]₂-modified single-crystalline and poly-crystalline gold electrodes in perchloric acid displayed two pairs of redox waves due to the successive removal or addition of electrons from or to the ligand-based orbitals. The effect of Eu[Pc(OC₈H₁₇)₈]₂ adlayers on the electron transfer rate at electrode/solution interface was investigated by using Fe(CN)₆^3−/4− couple as the redox probe. The redox behavior of Eu[Pc(OC₈H₁₇)₈]₂ adlayers and their accelerating effect on the electron transfer are closely associated with the electronic delocalization of rare earth sandwich complexes. However, in most cases, the Eu[Pc(OC₈H₁₇)₈]₂ adlayers were found to have inhibition role to complicated electrochemical reactions taking place on the gold surface, such as the gold substrate oxidation, the electrochemical reduction of oxygen, the electrochemical oxidation of ascorbic acid (Vitamin C) and the underpotential deposition (UPD) of silver.     

纸析法X射线荧光光谱测定湿法磷酸中的杂质

以滤纸为载体,实现液体样品固体化,在X射线荧光光谱仪上通过标准工作曲线法,定量测定湿法磷酸中CaO、MgO、Fe2O3、Al2O3等组分,介绍测定条件、试样制备、工作曲线的校正和数据处理。本法制样和分析过程具有简单、快速、准确及成本低的特点,能满足化工生产需要。     

新型QTRAP~(TM)四极杆-线性离子阱串联质谱仪的特点及应用

本文介绍新型QTRAPTM 四极杆 -线性离子阱串联质谱仪的基本原理和主要性能 ;并简述在药物筛选及代谢产物分析、蛋白分析和在天然产物结构分析方面的应用     

四极质谱检测中复合放大器的低噪声高带宽设计

四极质谱峰信号是10-11A到10-6A级的微弱电流,并且快速变化,所以在大动态范围内实现低噪声和高带宽是设计关键。设计一种开环增益(ac)可调整的同相输入复合跨阻抗放大器,分析ac对信号和噪声的作用。在较低放大倍率时,改变ac后同相输入复合放大器会降低自身产生的噪声,实现低噪声;在较高放大倍率时,改变ac后同相输入复合放大器能扩展被极高阻值的反馈电阻和寄生电容降低的信号带宽。实验结果表明：与反相输入复合放大器相比,同相输入复合放大器在106-107V/A放大时能降低5-30%噪声,在108V/A放大时扩展带宽1.8倍并提高10-15%质谱峰强度,提高了质谱峰的信噪比。     

圆柱形离子阱质谱仪关键技术研究及参数优化

采用EI电离源,研制了采用圆柱形离子阱为质量分析器的质谱仪,结合电子倍增管、小信号放大系统和数据采集卡,实现了离子的检测和数据采集,并通过LabVIEW控制整个系统。在真空系统中,优化了该质谱仪的灯丝电流、推斥极电压、背景气体压强及质量扫描速度等工作参数,并给出不同工作参数下谱峰的变化规律。使用优化后的参数对水杨酸甲酯进行检测,结果表明,该仪器性能良好,可以获得准确的有机物谱图信息,完成物质的质量分析。