Electrochemical investigations of single microparticles

Small electroactive particles are important materials in many technical processes. A new method to investigate single micro particles with diameters in the range of 10 μm is presented. Small numbers of these particles are fixed on a gold sheet and investigated by a capillary-based droplet cell. Cyclovoltammograms of different samples (cementite or Ni(OH)₂ particles) are presented as examples.     

Electrochemical investigations on composite iron electrodes

In spite of the many studies performed since the beginning of the last century, the Fe electrode, used as negative of both Ni/Fe and Fe/Air batteries, still poses several problems. For instance, according to the current literature, the following points are still not clear: (i) whether and how the depth of discharge affects electrode performance; (ii) what pathway the discharge follows, generally assumed as it is to involve consecutive Fe → Fe^II and Fe^II → Fe^III oxidation; (iii) why, at room temperature, only a minor fraction of the large theoretical capacity can be exploited. The present paper shows that deep discharges do increase Fe electrode performance, since they induce a transitory inhibition of hydrogen evolution. Likewise, Fe/Metal oxide composite electrodes have shown that the formation of Fe^III in discharge can take place directly from Fe, when the discharging rate applied is no longer compatible with the increase in electrode resistance due to oxidation products. Fe/Intermetallic compound composite electrodes have been studied as possible routes for increasing the efficiency of Fe capacity: useful indications have been gained as regards the compatibility of Fe with an IMC for charge storage.     

Electrochemical investigations of polypyrrole aluminum flake coupling

Polypyrrole (PPy) Al flake composite (PAFC) was synthesized by chemical oxidation of pyrrole in the presence of Al flake and was used to formulate a corrosion inhibiting primer. The anticorrosion performance of the PAFC coating for AA 2024-T3 was evaluated by accelerated salt spray, scanning vibrating electrode technique (SVET), galvanic coupling measurement and electrochemical impedance spectroscopy (EIS). The PAFC primer showed an enhanced anticorrosion ability for AA 2024-T3 compared to the Al flake primer and provided cathodic protection for AA 2024-T3 as evidenced by galvanic coupling measurement. A possible corrosion protection mechanism provided by the PAFC and the role of PPy in the formulation were discussed.     

Electrochemical investigations of sarcoma-related protein kinase inhibition

An electrochemical biosensor was developed for the determination of sarcoma (Src)-related protein kinase-catalyzed phosphorylation reactions in the presence of adenosine 5′-γ-ferrocenoyl triphosphate (Fc-ATP). The sensing platform is based on a highly specific amino acid sequence Glu-Gly-Ile-Tyr-Asp-Val-Pro (EGIYDVP), to which a Fc-PO₂ moiety can be transferred from Fc-ATP by the action of the Src kinase. The enzyme kinetics and kinase inhibition were investigated by square wave voltammetry (SWV). The kinetic parameters K_m and V_max were determined for Src protein kinase with respect to Fc-ATP co-substrate and were found to be 200 μM and 115 μA cm⁻² min, for phosphorylation of the EGIYDVP peptide substrate. Furthermore, the Src-catalyzed phosphorylation of Tyr was investigated in the presence of the small molecule inhibitors PP1, PP2, SU6656, and roscovitine. PP3 does not inhibit Src activity and was used as a control. The percent inhibition at half concentration, IC₅₀, values were determined for all inhibitors under the study and were estimated to be in the 5–30 nM range. The electrochemical study suggests that the increase in inhibition efficiency was in the order PP3 < SU6656 < roscovitine < PP2 < PP1.     

Mathematical modeling of the in-mold coating process

Fiber glass reinforced polyester parts compression molded from sheet molding compound (SMC) are prone to such surface inconsistencies as porosity and sinks. Even though it appears that some of these defects could be eliminated by techniques such as vacuum molding, the resulting surface, with current technology, is not yet consistently up to automotive standards for exterior body panels. In-mold coating (IMC) of SMC, is designed to fill porosity, reduce sinks, and furnish a primer-like coating, thus upgrading the part surface to automotive standards. As a consequence, IMC is generally an integral part of the molding cycle when producing compression molded SMC exterior automotive body panels. Most commonly, in-mold coating is injected after opening the press slightly so as to separate the mold cavity and the exterior surface of the part to make room for the coating. A second approach is to let the hydraulic pressure of the injected IMC open the mold. Here, we present a mathematical model of the process and show application in predicting injection pressures, fill times, and filling patterns. A comparison with experimental results is also presented. Cycle times required for IMC injection methods is also discussed.     

DEM investigations of fluidized beds in the presence of liquid coating

In this work, the impact of liquid coating on fluidized bed behavior is studied by performing DEM investigations. A wet coefficient of restitution model, accounting for the viscous and capillary forces in addition to the inelasticity of particles, is implemented in an open-source numerical tool — MFIX-DEM. The modified numerical tool is used to study the effect of the coating thickness and viscosity on the operation of a bed consisting of mono-sized solid spherical particles pre-coated with the same film thickness. The simulation results show that as the coating viscosity is increased, particles tend to stay close together, hence the fluidization behavior changes and the air passes through the system in the form of slugs. It is also shown that as the coating viscosity is increased the time-average wet coefficient of restitution, normal relative collision velocities, and bed height decrease. The effect of increasing the coating thickness is similar to the above, i.e. it results in a reduction of the time-averaged wet coefficient of restitution and normal relative collision velocities.     

汽车涂装工艺优化

传统的汽车涂装工艺存在能耗高、生产时间长和污染严重等问题.对汽车涂装工艺进行了优化——将“电泳漆+中涂+面漆”的涂装工艺优化为“电泳漆+面漆”,并在轻型车上进行了验证.试验表明,优化后涂装成本降低,能耗减少,缩短了生产时间,使单台车涂装成本和能耗由原来的242元降到41元,涂膜常规性能满足生产要求.     

Experimental and numerical investigations of the vacuum-forming process

This paper exmines the influence of process variables on final thickness distributions for vacuum-formed thermoplastic parts. The process variables investigated include evacuation rate, sheet surface temperature, mold temperature, and material slip over the mold surface. The experimental data presented include, in addition to thicknesses, sheet surface temperature obtained via infrared thermography. A finite element program to model the vacuum-forming process is discussed, and the wall thickness distribution predicted by this program for a vacuum-formed part is compared with the results of the experiments.     

Electrochemical and XPS investigations of cobalt in KOH solutions

The electrochemical behaviour of cobalt in KOH solutions of different concentrations was studied. The effects of applied potential, temperature and the presence of aggressive Cl^– ions were investigated. Different electrochemical methods such as open-circuit potential measurements, polarisation techniques and electrochemical impedance spectroscopy (EIS) were used. The electrochemical behaviour of cobalt in naturally aerated KOH solutions is characterized by three different regions according to the alkali concentration. Corrosion behaviour was observed at high concentrations (0.3–1.0 M); passivation at lower concentrations (0.01–0.05 M), and at intermediate concentrations (0.1–0.2 M) corrosion followed by passivation was recorded. The corrosion parameters (i _corr, E _corr, and R _corr) under various conditions were calculated. Equivalent-circuit models for the electrode–electrolyte interface under different conditions were proposed. The experimental impedance data were fitted to theoretical data according to the proposed models. The relevance of the proposed models to the corrosion–passivation phenomena occurring at the electrode–solution interface was discussed. The electrochemical experimental results and discussions were supported by surface analytical techniques.     

Electrochemical investigations on spectral sensitisation of silver halide crystals

Photocurrents and photovoltages were studied with single crystal plates of AgCl and AgBr as electrodes of an electrochemical cell. The photoresponse in the presence of sensitising dyes in the electrolyte corresponds to the absorption spectrum of the dye in that wave length range where the crystals do not absorb the light to any considerable amount. The technique described can be used for testing the suitability of dyes as sensitisers. The mechanism is discussed as electron injection from the excited dye molecules into the conduction band of the silver halides.     

一种无光丙烯酸漆涂装工艺

为解决无光丙烯酸漆涂装漆膜光泽偏高、表观效果差的弊病,采用新的涂装工艺,加入消光剂、流平剂等涂料助剂,控制施工粘度,所得漆膜光泽度低、表观效果好。确定最佳工艺参数为w(硅油溶液)0 01%、w(消光剂)8 5%、施工粘度(23±2)s。     

无磷涂装预处理新工艺

评述了涂装磷化预处理的环境污染及各国公布的限用措施和新的总磷排放标准,介绍了最近国内外开发的取代磷化的氟锆酸盐(氧化锆)预处理、硅烷偶联剂预处理和钢铁表面配合物膜预处理等3种类型预处理的优缺点,重点介绍了FPC405钢铁电泳涂装前防锈封闭剂、FPC406钢铁喷漆前防锈封闭剂和FPC408钢铁喷塑前防锈封闭剂等3种表面配...     

EIS法研究3种配套涂层体系的腐蚀电化学行为

采用电化学阻抗谱(EIS)研究了由水性无机富锌底漆、环氧中间漆和氯化橡胶面漆3种涂料配套而成的3种不同涂层体系在3.5%NaCl溶液中的电化学腐蚀行为,考察了氯化橡胶面漆、水性无机富锌底漆／氯化橡胶面漆、水性无机富锌底漆／环氧中间漆／氯化橡胶面漆这3种涂层体系的阻抗谱在浸泡过程中的演化并据此比较了3种涂层体系的防护性能。结果表明,两涂层体系的防护性能比单涂层的还要差,三复合涂层体系的防护性能最好。根据涂层腐蚀电化学阻抗谱特征推测,中间漆在三复合涂层体系中起到了使底漆和面漆结合更加紧密的桥梁作用。     

涂装双色车生产工艺

双色车属于特殊颜色车身,其外表面颜色通常在2种以上.精益的双色车生产工艺不仅能提高车身外观质量,而且能降低能耗及单车成本.本文对双色车生产工艺作了详细的介绍,包括色漆和清漆的第一、第二遍喷涂以及中涂遮蔽打磨等工艺流程.     

催化剂涂覆工艺研究进展

涂层式催化剂可以将载体的高强度和涂层的高反应性能相结合,目前已受到国内外的广泛关注。涂覆成型是涂层式催化剂制备过程中的关键工序,对催化剂的性能有重要影响。概述了浸涂成型、喷涂成型和滚涂成型等几种常见的涂覆工艺,介绍了不同涂覆方法在催化剂载体、成型助剂和工艺方面的特点和研究进展。在归纳和总结涂覆工艺对催化剂成型效果、涂层特性和产品反应性能的重要影响的基础上,提出未来还需对涂覆工艺进一步优化拓展,以拓宽涂覆技术的应用范围。     

Experimental investigations of semi-crystalline plasma polymerized polypyrrole for surface coating

Plasma polymerized thin film of conducting polypyrrole were deposited at room temperature by plasma enhanced chemical vapor deposition method using pyrrole monomer as precursor. The radio frequency (RF: 13.56 MHz, power supply: 30 W) was applied at constant argon gas pressure for the formation of plasma. The as grown thin films of polypyrrole have been characterized by ellipsometry, Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, atomic force microscopy (AFM), X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HRTEM). UV–vis spectra showed the optical energy band gap of 2.3 eV. XRD pattern of plasma polymerized polypyrrole has revealed a clear peak at inter-planer separation of 0.687 nm. It was also noticed by HRTEM analysis that the distinguished reflection at d =  0.687 nm has a broadening effect that may be correlated with the crystallinity of the material.     

Electrochemical process for the treatment of landfill leachate

In this paper, the anodic oxidation of a real leachate from an old municipal solid waste landfill has been studied using an electrolytic flow cell equipped with a lead dioxide (PbO₂) anode and stainless steel as the cathode. The influence of several operation parameters such as (i) the applied current (from 0.5 to 3 A), (ii) liquid flow rate (from 50 to 420 L h⁻¹), (iii) temperature (from 25 to 50 °C), and (iv) pH (from 3.5 to 8.2) on the COD removal rate, current efficiency, and energy consumption has been evaluated. The galvanostatic electrolyses always yielded COD values below the discharge limit (COD <160 mg L⁻¹); the COD removal rate increased with rising applied current, solution pH, and temperature, whereas it remained almost unaffected by the recirculation flow rate. These results indicate that the organic compounds were mainly removed by their indirect oxidation by the active chlorine generated from chlorides oxidation. The specific energy consumption necessary to reduce the organic load to below the disposal limit was 90 kWh m⁻³.