Development of a self-supported single-wall carbon nanotube-based gas diffusion electrode with spatially well-defined reaction and diffusion layers

This work reports on the development of a solvent-free method for the fabrication of a self-supported single-wall carbon nanotubes electrode, which is based on successive sedimentation of both SWCNT/surfactant and PtRu-SWCNT/surfactant suspensions followed by a thermal treatment at 130 °C. The as-prepared self-supported electrode showed sufficient mechanical strength for half-cell investigation and membrane-electrodes assembly fabrication. By using a Pt catalyst loading of 1 mg cm⁻², the overall thickness of the gas diffusion electrode reached 95 μm. Its electrochemical activity towards methanol oxidation was investigated by means of cyclic voltammetry and current-voltage polarisation measurements under half-cell and direct methanol fuel cell conditions.     

Characteristics of N2/SF6 mixture gas in creeping discharge developing in narrow gap with backside electrode

The flashover voltage with a backside electrode was found to be lower than that without the backside electrode. Under microsecond pulse voltage application, we describe the characteristics of a creeping discharge developed in the narrow gap with the backside electrode. Using a CCD camera and ultrahigh‐speed camera, we observed the corona extension processes. The lowest flashover voltage was found to be obtained at positive polarity with a SF₆ content D = 3%. In the corona extension obtained using an ultrahigh‐speed camera, peculiar differences were observed in the corona extension process. The corona extension increased, and rapid flashover was observed at D = 3%. Using a CCD camera, small coronas were detected from the backside electrode. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(2): 31–38, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20431     

不锈钢焊条E309L和E309Nb之对比

不锈钢焊条E309L和E309Nb的区别,主要是熔敷金属化学成分中C和Nb的含量不同。焊条E309Nb中添加了合金元素Nb,主要是为了提高抗晶间腐蚀、抗热裂纹的性能。由于E309L属超低碳焊条,焊缝金属具有γ+δ双相组织,φ(δ)=12%,因此也具有良好的抗晶间腐蚀和抗热裂纹性能。由于E309Nb含C量较高,且添加了合金元素Nb,因此高温强度优于E309L。但由于E309Nb很少使用,国内各大焊条厂基本不生产。     

In situ electrochemical impedance spectroscopy/synchrotron radiation grazing incidence X-ray diffraction—A powerful new technique for the characterization of electrochemical surfaces and interfaces

A marriage of electrochemical impedance spectroscopy (EIS) and in situ synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) has provided a powerful new technique for the elucidation of the mechanistic chemistry of electrochemical systems. In this study, EIS/SR-GIXRD has been used to investigate the influence of metal ion buffer calibration ligands, along with natural organic ligands in seawater, on the behaviour of the iron chalcogenide glass ion-selective electrode (ISE). The SR-GIXRD data demonstrated that citrate - a previously reported poor iron calibration ligand for the analysis of seawater - induced an instantaneous and total dissolution of crystalline GeSe and Sb₂Se₃ in the modified surface layer (MSL) of the ISE, while natural organic ligands in seawater and a mixture of ligands in a mimetic seawater ligand system protected the MSL's crystalline inclusions of GeSe and Sb₂Se₃ from oxidative attack. Expectedly, the EIS data showed that citrate induced a loss in the medium frequency time constant for the MSL of the ISE, while seawater's natural organic ligands and the mimetic ligand system preserved the medium frequency EIS response characteristics of the ISE's MSL. The new EIS/SR-GIXRD technique has provided insights into the suitability of iron calibration ligands for the analysis of iron in seawater.     

A novel approach for computing tertiary current distributions based on simplifying assumptions

A novel yet efficient method for the computation of simplified tertiary current density and surface concentration distributions in electrochemical processes is presented. The method is rooted in the important physiochemical property that the activation potential is constant and uniform for given electrode material during the electrolysis. The technique is attractive because it involves a single iterative procedure against the conventional doubly iterative procedure. The initial assumption of current distribution along the electrode is also not necessary, as it involves only an assumption of a suitable power series to solve steady state laminar convective diffusion. Accordingly the method is relevant only for electrodes of constant activation polarization, but this holds good for situations where the electrode configurations are such that the primary current density distribution is almost uniform and for situations where the Wagner number is high. To illustrate the utility of the technique the procedure is applied to some realistic problems encountered in electrochemical engineering such as the current distribution either in plane-parallel plate electrode with electrolyte flowing between them or a moving electrode with the electrolyte stationary.     

高性能PTCR电极浆料生产工艺的改进

通过增加分散剂松香的用量，提高了欧姆银浆的关键中间体材料银泥的质量稳定性。将压滤法应用于银泥洗涤工艺，既节省了设备投资，又避免了设备腐蚀。在欧姆银浆中掺入１０％的活性铝粉，降低了浆料成本，而且增强了浆料的工艺适应性。表层银浆的配制采用辊轧工艺替代球磨工艺，并对有机载体进行了调整，提高了生产效率，改善了膜层光洁度。     

特长锥孔的电火花加工

加工特长锥孔会遇到排屑困难的问题 ,导致孔的加工精度差、表面粗糙度值高等缺陷 ,通过对电极结构分析 ,提出了中空电极的专用结构 ,并通过实例验证此结构合理可行 ,由此推广到其它深孔(腔)加工 ,都可采用中空电极进行加工     

高炉装料设备用D-298焊条的研制

通过对Fe-Cr-Ni-B新合金系统熔敷硬度、耐磨性、抗裂性实验，并与通用堆焊焊条D-667的各项性能进行了比较，证明新的堆焊焊条比D-667焊条具有更好地综合性能。     

氧化铁系统气敏陶瓷的电阻温度特性 以及硫酸盐的影响

氧化铁系统陶瓷作为不掺贵金属催化剂的气敏材料需要提高其电阻温度稳定性才能适合定性和定量分析的要求，本文以ＣｕＯ－Ｆｅ２Ｏ３陶瓷烧结体为例，通过引入不同种类不同含量的硫酸盐，探讨了提高此系统对材料电阻温度稳定性的途径。     

EIT系统复合电极结构性能分析及优化设计

本文研究了医学电阻抗成像（MEIT）系统复合电极结构对敏感场分布的影响，并提出了一个具有边界强制等势点的有限元模型，通过计算机仿真，分析了复合电极宽度对敏感场分布的影响，并对不同激励模式下敏感电极的结构尺寸进行了优化设计。