不同温度下AZ41镁基合金牺牲阳极的电化学行为

不同温度下AZ41镁基合金牺牲阳极的电化学行为龚金保(中国科学院上海冶金研究所九六级硕士研究生上海200050)镁基牺牲阳极以往一般使用自然环境温度下保护地下钢铁构筑物,近年来提出了把它们扩大应用到加热的输油管道、贮罐等设备防腐蚀的新要求.然而,迄今为止还很少见到镁基牺牲阳极在较高温度下的电化学行为的报导.考虑到锌基牺牲阳极在较高温度下应用时电化学性能变劣,使我们联想到镁基牺牲阳极是否会出现类似的问题.本文研?...     

埋地钢质管道强制电流阴极联合保护研究

目的验证阴极保护系统在保护目标管道的同时对临近管道造成的杂散电流腐蚀,对比柔性阳极与阳极地床在保护管道的过程中产生的杂散电流污染情况,确定同沟铺设的不同管道联合保护方案。方法通过同一排流设备对相同区域的不同管线进行统一保护,阴极保护系统中的接地装置作为唯一的阳极,多条埋地管线作为电化学电池的阴极实现保护。结果阳极地床产生的杂散电流干扰明显强于柔性阳极材料;排流保护中,两条20 m埋地金属管道达到排流保护的范围时,柔性阳极的排流电压为1.2~1.52 V,远小于碳钢阳极地床的3.5~15 V,能够有效减少防护过程中电能的使用。结论同一阴极系统同时对多条金属管道或金属构筑物进行排流保护的措施可行。     

提高海洋环境钢筋混凝土构筑物耐久性措施综述

针对海洋环境钢筋混凝土构筑物过早腐蚀破坏,从混凝土防护、钢筋保护、包覆隔离保护、施工技术四个方面综述目前国内外对海洋环境下保护钢筋减少腐蚀、延长构筑物服役寿命所采取的技术措施,内容涉及:高性能混凝土、抗海水腐蚀水泥、阻锈剂、混凝土表面涂层、提高保护层厚度、钢筋涂层、耐腐筋、电化学保护、纤维玻璃钢或钢护筒包覆隔离、预防早期开裂、透水模板。重点讨论各措施的基本原理、特点、主要缺点和发展方向及工程应用。其中海工高性能混凝土是最经济、最基本和不可替代的,其他作为高性能混凝土基本措施的有效补充。     

图书推荐

编著:定价:出版日期:开本:页数:王强128.0元2012年9月16开644页该书系统介绍了电化学保护原理,详细叙述了电化学保护系统设计、系统施工、系统管理,还对交流、直流干扰,电化学保护技术经济分析,有关现行阴极保护技术标准、规范、规程及工程实例做了介绍。附录提供了有关电化学保护简明手册     

电化学保护技术及其应用：第九讲 阴极保护测量技术

1 概述 阴极保护技术作为一种能有效地防止金属腐蚀的电化学方法,目前已广泛应用于保护船舶、港湾和海洋设施以及地下管线和储罐.阴极保护测量技术是电化学和电子技术的结合,主要用于现场测量和监控保护系统的电位与电流,了解被保护结构的保护状况,检查保护系统的工作.     

接地网阴极保护中最佳保护电位的研究

采用电化学方法测量了镀锌钢和碳钢电极在不同电位下的电化学阻抗谱,建立了确定其阴极保护参数和最佳保护电位的方法。结果表明,采用电化学阻抗谱可以确定金属材料在给定条件下的阴极保护参数;实际应用证明整个系统能很好地延缓腐蚀,且有效地延长了接地网的服务寿命。同时介绍了一个阴极保护的智能远程监控系统。     

树脂材料在建筑防腐蚀工程的施工及应用综述

建筑物或构筑物的某些部位，由于各种化学介质直接接触，使建筑材料受到不同程度的物理、化学或电化学影响，导致局部或部分结构破坏，这就是腐蚀现象。产生腐蚀现象的介质，有些来自正常生产工艺过程，有些属于操作不严格、管理不善；也有一些因受周围环境的影响或由于受突发性事故波及，腐蚀是一不可逆过程，一旦造成危害，情况就相当严重。 建筑防腐蚀工程主要针对建筑物和构筑物的腐蚀情况，通过采取多种措施，有效地减少这些危害。以延长建筑。构筑物使用寿命，确保工业生产安全、产品质量稳定。树脂材料在建筑防腐蚀工程中具有广泛的…     

电厂热力设备用黄铜的阴极保护研究

采用电化学方法测量黄铜电极的极化曲线和在不同电位下的电化学交流阻抗,建立了确定其阴极保护电位范围和最佳保护电位的方法;并用显微镜观察电极表面形貌的变化,测量各保护电位下电极阻抗值等手段对确定的参数下的阴极保护状态进行了验证。结果表明,采用极化曲线和电化学阻抗谱可以确定金属材料的在给定的条件下的阴极保护参数。     

电化学保护和缓蚀剂应用技术（现代腐蚀科学和防蚀技术全书）

针对不同工业部门应用情况，理论联系实际地介绍了两类主要的防腐蚀工程技术，即电化学保护和缓蚀剂应用技术。电化学保护篇中介绍了阴极保护和阳极保护的原理、设计、施工技术、运行管理以及检测和控制；缓蚀剂与防锈技术篇则包括缓蚀剂和防锈技术，并分别介绍了它们的作用原理、应用、检测和管理控制。     

循环静水压力对牺牲阳极阴极保护的影响

实验模拟了常压和3.5MPa静水压力循环作用下,牺牲阳极阴极保护系统(CP)中阳极对阴极的保护。利用电化学测试法,结合SEM分析,对CP系统进行了电化学测量和腐蚀形貌观察,并对腐蚀产物进行了XRD成分分析。结果表明：在循环静水压力下,阴极的保护电位升高;牺牲阳极表面形成了一层相对致密的腐蚀产物壳层,导致其工作电位升高,放电能力下降;CP系统中斜率参数增大,牺牲阳极对阴极的保护效果变差。     

预应力钢筒混凝土管(PCCP)的阴极保护

预应力钢筒混凝土管(PCCP)是当前国内供水工程推广的新技术。因长期埋设在土壤中,PCCP管中的钢构件不可避免会发生腐蚀,其最佳防蚀的方法是阴极保护。本文结合国内外的实践经验,介绍了南水北调工程北京段PCCP管实施阴极保护的情况,以期为国内其它PCCP管的建设应用提供借鉴。     

Conventional and pulse cathodic protection of reinforced concrete: Electrochemical behavior of the steel reinforcement after corrosion and protection

The applicability and efficiency of an alternative for impressed current cathodic protection (CP) for reinforced concrete, based on pulse technology, was investigated. The technique, denoted as pulse CP (pCP), was evaluated on the basis of a comparative analysis to reference (non-corroding), corroding, and conventional CP conditions, in terms of long-term monitoring of electrochemical parameters for the embedded steel with time of corrosion and protection. The hereby reported results are for the total duration of the experiment, i.e., 460 days of conditioning, also presented in comparison with earlier stages. Protection was applied after corrosion was initiated (using corrosion medium of 5% NaCl), at different time intervals (here reported are starting points 60 and 150 days of age). Both CP regimes used current density of 5 or 20 mA/m² steel surface. The pulse CP was applied as a pulse-shaped block current (square wave) with the current itself being the feedback control signal, using 12.5–50% duty cycle at 500 Hz to 1 kHz frequency. Under equal environmental conditions and for a comparatively long period of application, the pulse CP was found to perform as effectively as the conventional CP with regard to electrochemical behavior of the steel reinforcement. Furthermore, the pulse CP technique was found to achieve more rapidly the so called “open circuit potential (OCP) passivity” as a result of an enhanced ion transport (chloride withdrawal) and more favorable cement chemistry (increased alkalinity around the steel reinforcement).     

海洋工程用钢表面喷涂Zn、Al和Zn-55%Al伪合金涂层的耐蚀性

热喷涂金属涂层是当前海洋环境下钢结构件防腐的首选方法,利用电弧喷涂技术在新型海洋工程结构用钢(Q345B钢)表面制备了Zn-55%Al伪合金热喷涂涂层,并与纯Zn涂层和纯Al涂层的耐蚀性进行了对比。结果表明:纯Zn涂层能提供较好的电化学阴极保护作用,但电化学性能欠佳;纯Al涂层表现出优良的电化学性能,但腐蚀后期产生点蚀;Zn-55%Al伪合金涂层具有更优越的耐蚀性和腐蚀防护性能。     

Microstructural properties of the bulk matrix and the steel/cement paste interface in reinforced concrete,maintained in conditions of corrosion and cathodic protection

Although rarely considered, especially within the investigation of steel corrosion phenomena or electrochemical protection techniques in reinforced concrete structures, the concrete bulk matrix has a significant contribution in the global performance of the system “reinforced concrete.” This is especially the case when chloride‐induced corrosion or electrical current flow [as within impressed current cathodic protection (CP)] are involved. In the latter cases, the concrete bulk matrix undergoes significant alterations in chemical composition, electrical properties, and microstructures, thus influencing the overall performance of the system. This work reports on the microstructural investigation of the bulk concrete matrix and the steel/cement paste interface in reinforced concrete, previously subjected to corrosion and CP for 460 days. The emphasis hereby is to evaluate the altered structural properties, i.e., porosity, pore size, permeability of the bulk cement matrix, and the steel/cement paste interface (translated to bond strength) as a result of chloride‐induced corrosion and two types of CP (conventional and pulse), compared to control (non‐corroding, non‐protected) conditions. The research revealed a major contribution and close dependence of all microlevel interfaces on the global performance of reinforced concrete. The electrical current flow (as in CP applications) was found to bring about unfavorable modifications to the material structure, both in the bulk matrix (reducing porosity) and at the steel/cement paste interface (enlarging interfacial gaps). The derived microstructural parameters show that the conventional CP leads to a higher level of structural heterogeneity, whereas the pulse CP exerts minimal or no effects, maintaining the material properties close to the reference (control) conditions, the underlying mechanism being a more homogeneous material microstructure.     

南海1 200 m深海环境Al-Zn-In合金阳极电化学性能研究

目的 研究对比了3种不同配方Al-Zn-In合金阳极在南海环境条件下的腐蚀形貌及电化学容量、电化学效率等性能参数,为深海工程装备的阴极防护设计提供可靠的参考依据。方法 通过在我国南海1200m深海试验架上搭载阳极阴极保护测试装置及数据采集、存储系统,采用自放电测试（Free Running Test,FRT）试验方法研究了阳极在110 d长周期条件下的电化学性能,采用超景深三维显微镜对其表面腐蚀形貌进行了观测。结果 1#—3#阳极下水后工作电位均快速活化,整个试验阶段,平均工作电位分别为-1.029、-1.033、-1.098 V(Ag/AgCl/海水);电化学效率分别为81.62%、78.02%、87.90%。仅自主设计的3#配方阳极的开路电位和电化学效率达到了UNE-EN 12496-2013阴极保护设计标准的要求。结论 与模拟深海环境下的恒电流测试（Galvanostatic Test,GST）短期试验（4 d）结果相比,同一配方阳极在深海110 d长周期FRT测试条件下的电化学效率分别降低15.13%,18.87%和8.14%。长周期FRT试验更接近实际阳极服役状态,可为深海阴...     

Numerical evaluation of the capacity of galvanic anode systems for patch repair of reinforced concrete structures

Cathodic protection (CP) is an electrochemical repair or corrosion prevention technique for steel structures exposed to a corrosive environment. For reinforced concrete (RC) usually impressed current CP is used, due to the comparably high resistivity of the concrete, serving as electrolyte. Nevertheless, the market provides a wide range of galvanic anode systems for RC structures. Their most common use is the application within the framework of partial concrete replacement due to chloride-induced corrosion. This patch repair is often accompanied by the so-called anode ring effect, causing accelerated corrosion of the rebar in the substrate concrete in the vicinity of repair patches. This is caused by the cathodic capabilities of the repassivated rebar. Galvanic anodes are reported to prevent this effect. In this paper, a numerical model is proposed, which is capable of determining the effectiveness of the method dependent on, for example, the type and quantity of anodes, rebar content, and geometry or climatic conditions. The method is presented for a specific set of input parameters and the applicability is discussed against the background of different protection criteria.     

混凝土中氯离子的预防及处理

氯离子对混凝土结构的腐蚀已引起广泛重视，本文就目前对混凝土防腐蚀所采取的隔离、修补、钢筋保护、电化学除盐及阴极保护法的具体应用作了简要论述。     

Cathodic protection of new and old reinforced concrete structures

Current and potential distributions measured on concrete slabs and simulated by computer modelling are discussed in relation with the application of cathodic protection to new reinforced structures as a corrosion preventive method. The results show high penetration of cathodic protection over the depth of uncontaminated concrete, so that even a rebar relatively distant from the anode can be polarized, whereas the penetration is limited to the rebars near to the anode in chloride contaminated slabs with corroding rebars. The great throwing power and the wide range of protection potentials for uncorroding concrete structure enable safe application of the cathodic protection even to new prestressed structures.     

Steel corrosion in concrete: Determinist modeling of cathodic reaction as a function of water saturation degree

The prediction of the long-term behavior of reinforced concrete structures involved in the nuclear waste storage requires the assessment and the modeling of the corrosion processes of steel reinforcement. This paper deals with the modeling of the cathodic reaction that is one of the main mechanisms of steel rebar corrosion. This model takes into account oxygen reduction and oxygen diffusion through a diffusion barrier (iron oxide and/or carbonated concrete) as a function of water saturation degree. It is demonstrated that corrosion rate of reinforcement embedded in concrete with water saturation degree as low as 0.9 could be under oxygen diffusion control. Thus, transport properties of concrete (aqueous and gaseous phase, dissolved species) are key parameters that must be taken into account to model electrochemical processes on the reinforcement.     

Effect of cathodic protection on macrocell currents: A viable method to monitor and control the efficiency of CP?

Corrosion protection of steel reinforcement in concrete structures by cathodic protection (CP) is a cost effective, reliable, and widely accepted method to stop and prevent the corrosion of the steel reinforcement. The efficiency of CP is usually monitored by the “24 h, 100 mV depolarization criterion,” a purely empirical criterion whose implementation is cost and labor intensive and that does not allow online control of CP. Within an extended research project on CP applied to concrete members of a highway bridge exposed to penetrating moisture, three sets of macrocells (MC), each composed of five MC sensors, were installed in conjunction with concrete resistance sensors and silver/silver chloride reference cells. Chloride profiles were determined from the cored or drilled powder originating from the installation of sensors and from drilling cores. Corrosion currents, steel potentials, and concrete resistance were monitored over a period of 1 year before, after installing the CP systems (which remained switched off for half a year for evaluating the effect of the conductive coating), and after start-up of the CP systems. The CP systems applied consist of a moisture resistant conductive coating. As expected CP has a pronounced effect on local MC currents: Anodic MC currents were reduced or changed into cathodic currents, whereas cathodic currents were only weakly influenced. By adjusting the applied protection current all anodic MC currents may be changed into cathodic MC currents. Results indicate that the 100 mV depolarization criterion is a conservative criterion in atmospherically exposed concrete; it is not reliable in strongly wetted concrete. There was no consistent correlation between the CP induced changes in the local MC currents and 24 h depolarization values indicating that large potential shifts induced by CP do not necessarily imply overprotection. Results show that monitoring MC currents before, during, and after CP operation allows to demonstrate in a transparent way the effect of CP on the corrosion of the steel reinforcement. Online monitoring of MC currents is proposed as a viable and comprehensible method to monitor and control the efficiency of CP.