Roles of humidity and heat treatment temperatures on YBa2Cu3O7-x coated conductors by trifluoroacetic acid-metal organic deposition process

YBa₂Cu₃O_7−x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition (TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure, degree of texture and critical properties of the films were evaluated. In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties, heat-treatment was performed at various temperatures with the other processing variables fixed. The films were calcined at 400–430 and fired at 750–800 °C in a 0–12.1% humidified Ar-O₂ atmosphere. The texture was determined by pole-figure analysis. The amount of the BaF₂ phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere, which led to increased critical properties. In addition, the microstructure varied significantly with firing temperature but changed little with calcining temperature. The highest I_C of 40 A/cm-width, which corresponds to J_C value of 1.8 MA/cm², was obtained for the films fired at 775 (in 12.1% humidity) after calcining at 400–430 °C. It is likely that °C the highest I_C value is due to the formation of a more pure YBCO phase, c-axis grains, and a denser microstructure.     

Influences of the electron donor groups on the properties of thiophene-(N-aryl)pyrrole-thiophene-based organic sensitizers

In this study, 1-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole-based metal-free organic dyes containing three different non planar electron donor groups such as methoxy or hexyloxy substituted triphenylamine and difluorenephenylamine were prepared in order to see the effect of electron donor groups on the opto-electrical properties and applied in dye-sensitized solar cells (DSSC). All three dyes showed broad absorption band in visible part of the solar spectrum (∼300 nm–600 nm). The dye (TPTDYE-3) containing sterically less hindered methoxy substituted triphenylamine was found to show relatively red shifted absorption compared to that of the dye (TPTDYE-4) containing hexyloxy substituted triphenylamine or the dye (TPTDYE-5) containing difluorenephenylamine. The optical band gaps of the three dyes were calculated to be 2.19 eV, 2.22 eV and 2.24 eV, respectively, and the highest occupied molecular orbital (HOMO) energy levels of the three dyes were found to be located at 0.65 V, 0.68 V and 0.75 V, respectively. The DSSC performance of each dye was investigated with and without coadsorbent. The maximum solar to electrical energy conversion efficiencies (η) of the DSSCs made from only sensitizer were 4.18%, 5.28% and 5.42% while those of the DSSCs made from sensitizer with coadsorbent were 5.47%, 5.58% and 5.63%, respectively.     

In situ characterization of N-methylpyrrole and (N-methylpyrrole-cyclodextrin) polymers on gold electrodes in aqueous and nonaqueous solution

Electrosynthesized polymers of N-methylpyrrole (NMPy) and N-methylpyrrole-2,6-dimethyl-β-cyclodextrin NMPy-β-DMCD were characterized with cyclic voltammetry and in situ conductivity measurements in aqueous and nonaqueous solutions. In situ UV–vis-spectra of PNMPy and poly(NMPy-β-DMCD) films show differences both in band absorbances and in energies of polaronic transitions. For the electrosynthesis of poly(NMPy-β-DMCD), a (1:1) (mole–mole) NMPy-β-DMCD supramolecular cyclodextrin complex of N-methylpyrrole was used as starting material, which was previously characterized with proton NMR spectroscopy. The PNMPy and poly(NMPy-β-DMCD) films were prepared from 0.05 M NMPy and 0.05 M NMPy-β-DMCD complex, respectively, in 0.1 M LiClO₄ aqueous solution and 0.1 M LiClO₄ nonaqueous solution (acetonitrile) by electropolymerization. A slight positive shift of the oxidation peak and further differences are observed for poly(NMPy-β-DMCD) electrosynthesized in comparison with PNMPy prepared in both aqueous and nonaqueous solutions. Different CVs and ΔE_p of films were observed at various scan rates. In situ conductivity values of PNMPy and poly(NMPy-β-DMCD) films prepared in nonaqueous solution (acetonitrile) show higher values than with films prepared in aqueous solutions.     

有机功能团及矿化液离子对羟基磷灰石晶体生长的影响

通过X射线衍射(XRD)、扫描电镜(SEM)等分析手段研究了不同有机功能团和无机离子对矿化相的形核、晶体结构、形貌和结晶学定向生长的调控作用及机理.结果表明:1)自组装有机膜能加速HAP晶体的形核速率,且有机膜功能团的种类及结构对HAP晶体的形核与取向生长起决定作用.功能团为-NH2的有机膜所诱导的晶体为定向生长且规则排列的纳米片状HAP晶体;-SO-3所诱导的晶体以辐射方式生长,晶体的排列有一定规律;在十二烷基磷酸酯有机膜存在下,所诱导的晶体也呈片状,但晶体的排列和结晶学取向无一定规则.2)矿化液中无机离子对HAP晶体的生长和形貌有显著影响.Cl-离子通过与HAP晶体中的OH-离子进行交换,并参与HAP晶体的结晶,从而改变HAP晶体的结晶习性,使生成的HAP呈片状;Mg2 离子通过争夺有机膜上的形核位点和占据HAP晶体表面的生长点或进入HAP晶体间隙,降低HAP晶体的形核速率,并细化晶粒;SO2-4离子通过在HAP表面吸附,使HAP晶体尺寸细化,且呈团蔟状生长.     

Forecasting of mechanical properties of covered electrode containing La/CeO_2 based on fuzzy neutral network

In order to improve the mechanical properties of deposited metal of ilmenite type welding electrode,CeO_2/La rare earth elements were added into electrodes based on E4301 electrode, then electrodes were produced,test plates were welded, and mechanical properties were tested based on National Standards of China. For the sake of solving the problems of large amount of mechanical properties tests, long test cycle and high test cost during the conventional production process of electrode, a prediction model of the mechanical properties of deposited metal based on Takagi-Sugeno(T-S) fuzzy neural network was established. Mn, Si and C contents of medium manganese in electrode, CeO_2, and La contents of electrode and welding speed were selected as input variables of the prediction model, and the tensile strength, lower yield strength, elongation, impact energy and hardness of deposited metal were selected as output variables. Finally,predicting experiment was done under test samples, and results show that average relative prediction error of the tensile strength, lower yield strength, elongation and hardness are 0.91 %, 2.57 %, 4.94 % and 1.94 %, respectively, which reach the need of actual production. The results of prediction show that the mechanical properties of deposited metal of electrode containing rare earth can be forecasted accurately through material composition of electrode and welding parameters based on T-S fuzzy neural network model.     

高硫高有机物型铝土矿反浮选同步脱硫脱有机物试验研究

针对高硫高有机物型铝土矿进行反浮选同步脱硫脱有机物试验研究,硫含量1.65％、碳含量0.42％和有机碳含量0.32％的原矿石,经一粗一精一扫工艺流程,得到产率95.32％、硫含量0.15％、碳含量0.25％和有机碳含量0.15％的铝精矿,和产率4.68％、硫含量32.25％和碳含量3.87％的硫精矿,为高硫高有机物...     

Effect of dipole layer of Alq3 and metal on organic electroluminescence

The effect of dipole layer of Alq3 and metal on organic electroluminescence in organic light-emitting diodes （OLEDs） was discussed. The relations among energy level alignment, interface charge transfer and dipole layer formation were well analyzed. An interface dipole layer and charge transfer were observed by XPS and UPS. As for Alq3 with metallic film such as Al and Mg, N 1s, O 1 s and C 1s all move to low binding energy. Both Alq3/Al and Alq3/Mg have different electron spectrum from that of simple Alq3 film. It is really the reason of the interface energy change that the metal atoms located near the interface move to organic layer and then chemically interact with O and C of Alq3. The injection voltage barrier heights of electrons at Alq3/Al and Alq3/Mg interface are 0.1 eV and 0.2 eV, respectively. Charge transfer lowers electrons injection voltage barrier height and forms good electrons injection interfaces. The width of dipole layer is about 5 nm. The knowledge of such interface dipole layer is essential for a proper understanding of the physical processes at the metal/organic interface.     

Ground-based investigation of atomic oxygen effects on naked Ag and Ag with protective organic coatings

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High mobility n-channel organic field-effect transistors based on soluble C60 and C70 fullerene derivatives

We report on n-channel organic field-effect transistors (OFETs) based on the solution processable methanofullerenes [6,6]-phenyl-C₆₁-butyric acid ester ([60]PCBM) and [6,6]-phenyl-C₇₁-butyric acid methyl ester ([70]PCBM). Despite the fact that both derivatives form glassy films when processed from solution, their electron mobilities are high and on the order of 0.21 cm²/V s and 0.1 cm²/V s, for [60]PCBM and [70]PCBM, respectively. Although the derived mobility of [60]PCBM is comparable to the best values reported in the literature, the electron mobility of [70]PCBM is the highest value reported to date for any C₇₀ based molecule. We note that this is the only report in which C₆₀ and C₇₀ methanofullerenes exhibit comparable electron mobilities. The present findings could have significant implications in the area of large-area organic electronics and organic photovoltaics where C₆₀ derivatives have so far been the most widely used electron acceptor materials.     

Self-healing mechanism of a protective film prepared on a Ce(NO3)3-pretreated zinc electrode by modification with Zn(NO3)2 and Na3PO4

Self-healing mechanism of a protective film against corrosion of zinc at scratches in an aerated 0.5 M NaCl solution was investigated by polarization measurements, X-ray photoelectron spectroscopy (XPS) and electron-probe microanalysis (EPMA). The film was prepared on a zinc electrode by treatment in a Ce(NO₃)₃ solution and addition of aqueous solutions containing 9.98 or 19.9 μg/cm² of Zn(NO₃)₂ · 6H₂O and 55.2 μg/cm² of Na₃PO₄ · 12H₂O. After the coated electrode was scratched with a knife-edge crosswise and immersed in the NaCl solution for many hours, polarization measurements, observation of pit formation at the scratches, XPS and EPMA were carried out. This film was remarkably protective and self-healing against zinc corrosion on the scratched electrode. The cathodic and anodic processes of zinc corrosion were markedly suppressed by coverage of the surface except for scratches with a thin Ce₂O₃ layer containing a small amount of Ce⁴⁺ and the surface of scratches with a layer composed of Zn₃(PO₄)₂ · 4H₂O, Zn(OH)₂ and ZnO mostly.     

Influence of sodium chloride and weak organic acids (flux residues) on electrochemical migration of tin on surface mount chip components

Abstract

The electrolytic properties of sodium chloride and no-clean solder flux residue, and their effects on electrochemical migration and dendrite growth on surface mount chip capacitors were investigated. The leakage current dependency on concentration of contaminants was measured by a solution conductivity method and compared with current measurements using DC voltage. The effect of electrolyte concentration and potential bias on the probability of electrochemical migration was investigated using a water droplet method on chip capacitors. The results from leakage current and conductivity measurement showed a difference which is caused by polarization effects, and demonstrated existing issues when indexing contamination levels on printed circuit board assemblies using a standardised solvent extract method. The experimental results showed that dendrite growth was dependent on the type and amount of contamination. The probability of migration becomes less dependent on the amount of contamination for sodium chloride at high concentrations. However, for organic acids from flux residues the migration probability shows an abrupt decrease with increasing concentration, which is attributed to a pH change in the condensed electrolyte phase.     

The nature of the surface film on steel treated with cerium and lanthanum cinnamate based corrosion inhibitors

The corrosion inhibition mechanisms of new cerium and lanthanum cinnamate based compounds have been investigated through the surface characterisation of the steel exposed to NaCl solution of neutral pH. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to identify the nature of the deposits on the metal surface and demonstrated that after accelerated tests the corrosion product commonly observed on steel (i.e. lepidocrocite, γ-FeOOH) is absent. The cinnamate species were clearly present on the steel surface upon exposure to NaCl solution for short periods and appeared to coordinate through the iron. At longer times the Rare Earth Metal (REM) oxyhydroxide species are proposed to form as identified through the bands in the 1400-1500 cm⁻¹ region. These latter bands have been previously assigned to carbonate species adsorbed onto REM oxyhydroxide surfaces. The protection mechanism appears to involve the adsorption of the REM-cinnamate complex followed by the hydrolysis of the REM to form a barrier oxide on the steel surface.     

The effect of the carbon nanotubes surface oxidation on the morphology and properties of poly(N-vinylcarbazole) coated multi-walled carbon nanotube nanocables

This article describes the effect of carbon nanotubes (CNTs) outer surface oxidation on the morphology and properties of poly(N-vinylcarbazole) (PNVC)-coated individual multi-walled CNT (MWCNT) nanocables. Surface oxidation of MWCNTs has been carried out by refluxing MWCNTs with 5 M nitric acid (HNO₃) at 80 °C for 1 h. The PNVC-coated MWCNT nanocables are synthesized by in situ solid-state polymerization of N-vinylcarbazole monomers in the presence of oxidised MWCNTs (o-MWCNTs) at an elevated temperature. The PNVC-coated MWCNT nanocables are characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning and transmission electron microscopes, photo-luminescence spectroscopy, and direct-current conductivity measurements. Results show that the uniform nanolayer coating of PNVC decreases the inherent bulk conductivity of MWCNTs, but significantly increases the optical properties of MWCNTs.     

基于Pro/E和MasterCAM的注塑模设计与加工

为了提高注塑模具设计与加工的质量和效率,更好地发挥各软件的特点,采用多种软件联合应用。以照相机面板注塑模为例,介绍了Pro/E在注塑模具设计中的应用以及在MasterCAM环境下的CAM实现。阐述了Pro/Moldesign的模具设计流程和优势,并运用MasterCAM对照相机面板凹模进行了仿真模拟加工。通过实例表明,两者结合使用能缩短模具生产周期和提高模具精度。     

基于Pro/E与ANSYS的一模多腔模具热分析

针对一模多腔模具在加热过程中由于散热问题引起的模腔温度不一致问题,应用Pro/E建立有限元热分析模型,基于热分析理论并采用ANSYS对模具的温度场分布进行分析,实现了几何建模和有限元分析的无缝集成,为模腔温度控制提供了参考,达到生产过程中模腔温度一致的目的.     

基于Pro/E和MasterCAM的门铃面板数控加工

阐述了用Pro/E软件进行门铃面板模具设计,然后将图形数据转换到MasterCAM软件中进行数控编程的基本方法,重点论述了门铃面板凸、凹模加工工艺方案的合理性。     

Study of modeling and simulation of full digital controlled PMIG／MAG welding system based on Matlab／Simulink

This paper presents an integrated simulation model for full digital controlled PMIG/MAG welding system with Matlab/Simulink, and it consists of power inverter, digital control system and dynamic arc-load model. An integrated simulation study was done for fuU digital PMIG/MAG welding, and a method of connecting dynamic arc-load model to the system with controlled current source was presented, in addition, the simulation results were utilized to study the issues of digital control PMIG/MAG welding in this paper. The experimental results validated the developed simulation model, and this simulation study can be applied in implementation of the full digital PMIG/MAG welding and analysis of system dynamic process.     

基于B/S模式的钣金展开/切割CAD/CAM系统研发

建立了基于B／S模式的钣金展开CAD／CAM系统。论述了基于ASP理念钣金展开／切割CAD／CAM系统的计算模型和编程原理、用户身份认证机制、零件信息输入与处理，NC指令生成及浏览器端的动态加工模拟、系统管理机制等关键技术及实现方法。