电流效率对铝材电镀的影响

1　前言在电镀生产中 ,铝一直以难镀金属著称 ,其原因是铝本身很活泼 ,表面易生成一层氧化膜 ,严重影响镀层与基体的结合力。在常规的前处理中 ,常采用浸锌或锌镍合金 ,但是经过此处理的铝件在有些镀液中电镀效果也不好 ,镀层鼓泡、起皮等。笔者经过大量实验以及生产实践 ,得出这些故障也与镀液的电流效率有关的结论。2　铝材的前处理工艺(1)化学除油 ,采用常规化学除油液 ;(2 )酸蚀活化 ,采用硝酸为主的酸液 ;(3)特殊的前处理工艺 ,即浸锌或锌镍合金。3　经前处理的铝材在不同镀液中的表现(1)在电流效率很高的镀液中电镀 ,如氰化镀银或瓦特…     

油管阴极保护器在腐蚀井中的应用

为了解决文卫濮结合部卫79断块区的油井腐蚀严重问题,通过对油井腐蚀的研究,发现油水井中由于使用的金属材料材质不同而引起电化学腐蚀,采用牺牲阳极阴极保护技术,进行现场使用,经济效益明显,利于治理改善油井的腐蚀状况。     

建筑铝材的氟碳喷涂

介绍了氟碳喷涂工艺，喷枪选择和涂层测试标准。     

埋地石油管道阴极防腐措施与风险预警研究

根据埋地管道阴极保护现状,总结了阴极保护原理、分类.阴极保护主要是基于电化学腐蚀原理,采用外加电流及牺牲阳极两种保护方式.分析了目前准则存在的不足,阴极保护准则没有对管道允许受到的直流干扰程度做出明确的规定且-850 mV(CSE)准则不适用交流干扰情况,另外GB/T 21448—2008准则的适用温度不能超过40℃....     

粉体铝材清洗剂的制备及性能研究

本文研制的粉体铝材清洗剂是一款适用于铝基材的工业粉体脱脂剂,本产品通过无机盐、环保高效组分进行复配,借助超声波清洗方式对铝基材表面的防锈油、挥发油等油污进行清洗,清洗后对铝基材无腐蚀。通过研究显示：本品为粉状产品,溶解性好,对铝基材无腐蚀,且对防锈油、挥发油等油污清洗效率高达95%以上,清洗后基材表面含油量低于10 mg/m²,能够满足相关行业需求和铝材清洗工艺。     

Study of sacrificial anode cathodic protection of buried tanks: Numerical modelling

A finite element numerical model was set up to calculate the secondary distribution of potential and current density at the surface of a buried tank. The steel gas tank of interest was protected by both coating and two sacrificial anodes (magnesium alloy or zinc). The dispersion of actual soil properties was taken into account by use of three typical soils. The comparison of two dimensional and three-dimensional models shows that the 2D model is obviously both convenient and time saving. The numerical model allows the calculation of the cathodic protection current and of the local potential in every point of the tank. The model intends to compare the relative influence of coating quality, electric conductivity of soil and position, size and type of the sacrificial anodes (magnesium or zinc). Soil conductivity and coating porosity appear as the two most influential parameters. This model justifies the interest of the tank experimental potential and current measurements.List of symbols     

Investigation of oxidation potentials of substances accumulated during cathodic polarization of aluminium

High-purity aluminium immersed in a neutral sodium chloride solution was submitted to galvanostatic pulses of different duration in a current density range between 10⁻⁵ and 10⁻¹ A cm⁻², as well as to a defined anodic current following immediately each cathodic pulse. Potential transients were recorded at time scales ranging between ms and 10³s. Interfacial and kinetic parameters for the cathodic reaction were extracted from cathodic transients. Anodic transients revealed several levels of oxidation potentials at which different substances produced in the cathodic process, were oxidized. It was found that, when the cathodic processes take place at the bare metal surface (at c.d. sufficient to cause complete hydration of the oxide film), the amount of substances formed is proportional to the square root of the total cathodic charge passed during a pulse.     

Cathodic protection and cathodic preventionin concrete: principles and applications

The paper deals with the principles of cathodic protection for atmospherically exposed concrete structures, the various protecting effects induced by the cathodic polarization and tests and field experience results. The differences between the cathodic protection applied for controlling the corrosion rate of chloride contaminated co nstructions and that applied to improve the corrosion resistance of the reinforcement of new structures expected to become contaminated are then underlined and discussed. The more recent applications of cathodic protection on carbonated concrete are also illustrated. The operating conditions (voltage and current applied), the throwing power, the protection conditions which avoid the risk of hydrogen embrittlement in prestressed structures are also discussed. Examples of cathodic protection and of cathodic prevention are also presented.     

Electrochemical properties of composite anodes for cathodic protection

Comparative results of electrochemical investigations of polymeric composites with different contents of carbon black and graphite activated with ruthenium oxides are presented. Electrochemical impedance measurements (EIS), enabling determination of electrical and electrochemical properties of polymeric composites, were accompanied by potential measurements performed during a 21-day galvanostatic polarization at 5 A m^–2 current density. Gravimetric measurements were also made to determine the extent of anode consumption. It was demonstrated that the presence of ruthenium oxides characterised by high electrocatalytic activity in the polymeric composites causes an improvement in the polarisation characteristics, a decrease in the value and improvement in stability of the potential during long-term operation, and also a decrease in the anode consumption, as compared to composites exclusively containing activated carbon black.     

阴极保护用涂层钛电极(二)

介绍了电化学法除海洋生物用Ti/Pt/IrTa涂层电极,钢筋混凝土阴极保护用Ti/RuTiSnMn涂层电极,以及土壤阴极保护用Ti/RuTiIrZr涂层电极。给出了几个阴极保护用辅助阳极的实例。     

A mathematical model for the internal cathodic protection of cylindrical structures by wire anodes

The applicability of a two-dimensional mathematical model of the impressed current cathodic protection (CP) system of the interior wall of a cylindrical structure was investigated. The modelled system was an axisymmetric cylindrical column filled with electrolyte with a wire anode running along its entire length and displaced from the column axis. Model inputs included anode and cathode dimensions, the anode-to-cathode distance, the electrolyte conductivity and limiting current density of oxygen reduction. A semi-analytical solution to the Laplace equation was used to compute the distribution of electrical potential. From these results, the nonuniform current density distribution was obtained to a first approximation by entering the computed values of the position-dependent cathode polarization potential into the nonlinear experimentally obtained polarization expression. The experimental electrical potential distribution compared well with that predicted by the model. Results showed the possibility of overprotection occurring in the system. The mathematical analysis was also extended to the case of a system with two wire anodes.     

钌铱钛合金电极的脉冲电流阴极保护研究

针对集输管道内壁阴极保护中,由于普通的参比电极无法应用的问题,对电化学性能稳定的钌铱钛合金作为参比电极时进行了阴极保护研究。研究发现,在NaCl溶液中,钌铱钛合金作为参比时,需要较长时间电位才能达到稳定状态,实验测得电位稳定时间为140min,同样条件下的甘汞参比电极电位稳定时间只有20min。两种参比电极之间电位存在差值,经过数据拟合后得出电位差为589.94mV。     

石化厂水冷器腐蚀与综合防护

根据对上海石化等厂的调研,介绍了水冷器腐蚀原因及综合防护对策,对水处理、耐蚀材料、涂镀层、阴极保护和清洗等作了分析.     

Dynamic characteristics of ship impressed current cathodic protection systems

Physical scale modelling was employed to identify the characteristics of the closed loop control systems for ship impressed current cathodic protection (ICCP) for different hull and operational conditions with three ICCP configurations. A one-hundredth scale metal model hull, with intact and damaged paint coatings, and with a damaged plastic cladding, were protected by ICCP under static and flowing electrolyte conditions. The three types of ICCP system all showed at least second order control characteristics in response to switch-on in static conditions. The damping ratios and natural frequencies of the dominant mode depended upon the hull condition and the ICCP system configuration. Characteristics of two single zone systems changed when they were combined as a two-zone configuration. Maximum peak overshoots, and times to overshoot, were lower with an intact paint coating than with a damaged, whereas natural frequencies and damping ratios were higher. Less damping occurred with damage to cladding than to a paint coating. In response to simulated underway conditions, driving voltages were oscillatory. Damping ratios were much lower than in static electrolyte and natural frequencies were higher. Such studies provide further insight into the processes of ICCP.     

Controlled synthesis of various SrTiO3 morphologies and their effects on photoelectrochemical cathodic protection performance

As an n-type semiconductor with typical perovskite structure, SrTiO₃ has broad research prospects in photochemical cathodic protection because of its suitable energy band structure. However, there is a lack of research on the effect of SrTiO₃ micro morphology on Photoelectrochemical cathodic protection performance. In this paper, a series of SrTiO₃ samples with controllable morphology were designed and prepared by changing the ratio of alcohol to water in the solvent, including nanoparticles (NPs), nano ball (NBs), nano rod (NRs), coral stone-like microspheres (CSLMs) and flower-like microspheres (FLMs). The experimental results show that FLMs samples have better photochemical cathodic protection performance. Under the condition of on light, the photocurrent density of FLMs samples reaches 9.2 μA. The photocurrent density of NPs samples is only 2.5 μA. The former is about 3.6 times that of the latter. The open circuit potential of FLMs samples has shifted from ?0.18 V to ?0.42 V, with a negative shift of 240 mV, while CSLMs samples have only a negative shift of 180 mV. In contrast, FLMs samples have a more negative shift of 60 mV. After four light cycle experiments, the performance of FLMs samples is stable without obvious change.