阴极保护技术在水工金属结构埋件上的应用

制作了水工金属结构埋件模型,研究不同种类牺牲阳极和外加电流方法对埋件的保护作用,以寻找切实可行的水工金属结构埋件长效保护方案。结果表明:采用牺牲阳极法进行阴极保护,当溶液电导率为2000μS/cm时,镁合金对水工金属结构埋件的保护距离可达到100cm,具有较好的保护效果;铝合金和锌合金由于表面钝化作用,对水工金属结构埋件起不到保护作用。恒电位极化方法可在不同电导率情况下对埋件起到较好的保护效果。     

Electrochemical measurements of cathodic protection for reinforced concrete piles in a marine environment using embedded corrosion monitoring sensors

This study developed a sensor to monitor the corrosion of reinforced concrete structures. Concrete pile specimens with embedded sensors were used to obtain data on corrosion and cathodic protection for bridge columns in a real marine environment. Corrosion potential, cathodic protection current density, concrete resistivity, and the degree of depolarization potential were measured with the embedded sensors in concrete pile specimens. The cathodic protection (CP) state was accurately monitored by sensors installed in underwater, tidal, splash, and atmospheric zones. The protection potential measurements confirmed that the CP by Zn-mesh sacrificial anode was fairly effective in the marine pile environment. The protection current densities in the tidal, splash zones were 2–3 times higher than those in underwater and atmospheric zones. The concrete resistivity in the tidal and splash zones was decreased through the installation of both mortar-embedded Zn-mesh (sacrificial anode) and outside an FRP jacket (cover). Considering the CP, the cathodic prevention was more effective than cathodic protection.     

钢筋混凝土构筑物电化学保护的新进展

综述了钢筋混凝土构筑物电化学保护的发展和现状,包括牺牲阳极系统和外加电流系统。内容涉及对不同类型、不同龄期构筑物的保护标准、保护参数选择、保护效果的评价以及检测、监测等诸方面。认为有必要加强电化学驱氯、电化学再碱化等新技术的研究;根据构筑物的不同使用环境,采用多种有效的、综合的保护措施。     

铸造和挤压镁合金牺牲阳极的应用进展

镁合金牺牲阳极是适用于对在土壤、淡水及海水等介质中工作的金属(主要是钢质)设施进行阴极保护用的一种特殊的电化学功能材料,其用途越来越广泛。本文介绍了铸造和挤压镁合金牺牲阳极材料的一些基本特点、新的镁阳极产品类型,并对镁阳极制造与应用中的一些最新进展情况作了探讨。     

Throwing power of cathodic prevention applied by means of sacrificial anodes to partially submerged marine reinforced concrete piles: Results of numerical simulations

The paper deals with the determination of current and potential distribution in reinforced concrete elements partially submerged in seawater aimed at predicting the throwing power of cathodic prevention applied by means of sacrificial anodes. Experimental results from previous laboratory tests showed that the throwing power of cathodic prevention is higher compared to that of cathodic protection [1]. In order to extend the results obtained on small-scale specimens to elements of higher dimensions, FEM numerical simulations of potential distribution were carried out. Several cases were considered, representative of conditions differing in electrochemical behaviour of steel bars, geometry of the pile and of sacrificial anodes, concrete resistivity. The results allowed to discuss the role of different factors on the throwing power that can be reached by using sacrificial anodes immersed in the seawater to protect reinforcing steel bars in the emerged part of a pile.     

Possibility of High Phosphorus Pig Iron as Sacrificial Anode

Cathodic protection is an effective method to control the corrosion of underground pipelines and submerged structures. In the present work, high phosphorus containing pig iron was utilized as sacrificial anode for cathodic protection of underground mild steel plates and the results were compared with that of a commercially pure magnesium sacrificial anode. Driving potential and current between the galvanically coupled sacrificial anodes and mild steel plates were continuously monitored in real time for one month. Microstructure and morphology of the corrosion products formed on the surface of pig iron, magnesium sacrificial anodes and mild steel plates were observed with the help of optical microscope and scanning electron microscopy, and phase identification were performed using x-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. The distribution of phosphorus in the pig iron matrix and soluble rust formation on the surface of pig iron under buried condition were critical from the point of sacrificial effect, indicating the possible scientific reasons for high phosphorous pig iron to be used as sacrificial anode.     

Optimizing the electrode position in sacrificial anode cathodic protection systems using boundary element method

In this paper, a sacrificial anode cathodic protection problem of 2D steel storage tank was simulated using boundary element method. The tank was protected by a zinc anode located directly on structure wall. Data obtained from potentiodynamic measurements were used as boundary condition. In this study, optimum location of the anode was determined, and the influence of anode length and paint defect on the level of protection provided by system were investigated. This study showed that boundary element method is beneficial in modeling and analyzing cathodic protection systems and calculated results were consistent with expectations from the basic corrosion concepts.     

Prevention of steel corrosion in concrete exposed to seawater with submerged sacrificial anodes

This paper presents the results of a study of the effectiveness of submerged sacrificial anodes in preventing the onset of pitting corrosion in the emerged part of marine piles. Experimental tests were carried out on reinforced concrete columns with steel embedded both in chloride free concrete and chloride contaminated concrete in order to compare the effects of sacrificial anodes on passive steel and on corroding steel. Results have shown, at least under the present testing conditions, that sacrificial anodes may be more effective in preventing corrosion initiation (i.e. in providing cathodic prevention) than in controlling ongoing pitting corrosion (i.e. in guaranteeing cathodic protection). Monitoring criteria for this type of prevention are also discussed.     

Corrosion behaviour of dc magnetron sputtered Fe1−xMgx alloy films in 3 wt% NaCl solution

Fe_1−xMg_x alloy films (with x ? 43.4 at.% Mg) were deposited by dc magnetron sputtering onto glass slide substrates. The objective of this study was to characterise the corrosion properties of these alloys in saline solution for application as new friendly environmentally sacrificial coatings in the protection of steel structures. The morphological and structural properties of the alloys were systematically studied prior to electrochemical experiments, and then the degraded surfaces were analysed to determine the composition and nature of corrosion products. Alloys with <25  at.% Mg were single-phase body-centred cubic (bcc) with enlarged lattice parameters, whereas for magnesium contents above 25 at.%, amorphisation occurred. The reactivity of the alloys in saline solution is strongly dependent on the Mg content and the alloy structure. The incorporation of magnesium leads to an open circuit potential shift of the alloy towards more negative values, that confers an attractive interest of these alloys as sacrificial coatings. A transition in corrosion activity is observed at 25 at.% Mg from which the reactivity decreases with the magnesium content increase. The evolution of the alloy corrosion behaviour is discussed in terms of structural and corrosion products evolution versus magnesium content.     

Cut-edge corrosion of a Zn–55Al-coated steel: A comparison between sulphate and chloride solutions

Ex situ observations and in situ measurements of current and pH distributions over cut-edge coated steels revealed that Zn–55Al coatings are sacrificial only in chloride solutions, because of an activation of both Zn- and Al-rich phases present in the coating. In sulphate solutions, an efficient cathodic protection occurs only for short times of immersion, because only Zn-rich phases are active in this medium. The low solubility and strong acidification induced by Al(OH)SO₄ allows only short distance cathodic protection, but cannot prevent red rust precipitation on the steel surface.     

Development of nano cerium oxide incorporated aluminium alloy sacrificial anode for marine applications

Aluminium-zinc alloy sacrificial anodes are extensively used for cathodic protection. The performance of the sacrificial anodes can be significantly improved by incorporation of microalloying elements in the aluminium matrix. In the present work nano cerium oxide particles of different concentrations, ranging from 0 to 1 wt% were incorporated for activating and improving the performance of the anode. The electrochemical test results revealed the increased efficiency of the anode. The electrochemical impedance spectroscopy revealed the information that the presence of nano cerium oxide in the anode matrix caused effective destruction of the passive alumina film, which facilitated enhancement of galvanic performance of the anode. Moreover, the biocidal activity of cerium oxide prevented the bio accumulation considerably which enables the anodes to be used in aggressive marine conditions.     

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.     

城镇燃气埋地钢质管道牺牲阳极阴极保护的设计

在明确了阴极保护的管道条件前提下,文章简述了埋地钢制管道牺牲阳极阴极保护基本原理,确定了应采用的阳极材料;给出了规范要求和设计参数、以及镁阳极接地电阻的简化计算公式;明确了不宜使用钢套管及对水泥套管内管道采取的保护措施;给出了阳极地床填包料的组分。     

用电化学阻抗技术研究阴极保护

介绍电化学阻抗谱（ＥＩＳ）在研究阴极保护方面的应用，根据受有极保护金属的阻抗特征，可以确定实际保护率达到极大的最佳阴极保护保护电位，ＥＩＳ可以用于监测土壤和混凝土钢结构受阴极保护时的腐蚀情况，海水中阴极保护时形成的钙质沉积层的保护性能可由ＥＩＳ的参数来反映。ＥＩＳ变化趋势可还以反映Ａｌ－Ｚｎ－Ｉｎ合金牺牲阳极沿晶界的择优溶解。     

阴极保护用阳极

介绍了牺牲阳极材料中镁基、锌基、铝基阳极的化学成分和性能特点，以及多种外加电流阴极保护用阳极材料的特点。通过对石墨阳极、高硅铸铁阳极和铅银合金阳极、镀铂阳极和混合金属氧化物阳极的性能比较，认为混合金属氧化物阳极是最为理想和最有前途的辅助阳极材料。     

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...     

舟山某码头钢管桩牺牲阳极阴极保护系统检测

舟山某码头钢管桩采取牺牲阳极阴极保护已10余年。通过检测阳极的表面形貌,计算阳极使用寿命,测量保护电位和检查钢管桩腐蚀状况,对牺牲阳极保护效果进行了评价和分析。结果表明,10年间钢管桩受到了充分有效的保护,阳极剩余寿命在10年以上,实际使用寿命将大于设计寿命。     

Zn-Al-Cd合金对20#钢牺牲阳极保护行为

以工厂换热器为研究背景,采用极化技术和自放电法,研究了不同温度下Zn-Al-Cd合金牺牲阳极和纯Zn阳极在地下井水和模拟海水中对20#钢的牺牲阳极电化学性能。开路电位、工作电位及极化曲线的测试结果表明：在30~80 ℃范围内,Zn-Al-Cd合金、纯Zn和20#钢在两种介质中均未出现电位极性逆转现象,牺牲阳极具有良好的电化学性能;Zn-Al-Cd合金在地下井水中生成的保护膜比模拟海水中的稳定;牺牲阳极合金成分的优化,可以有效防止电位逆转行为。     

复合式牺牲阳极保护钢管桩的试验研究

本文报道在淡水环境中采用铝合金和镁合金复合式牺牲阳极对钢管桩进行阴极保护的可行性研究。分别检测了安装3组、4组或5组复合牺牲阳极后,钢管桩1天和7天的极化电位,评估了该方案的实际保护效果,确定了较为合理的镁合金与铝合金牺牲阳极的用量和比例。     

淡水介质中筒状设备内壁阴极保护电位分布研究

研究了室温自来水介质中用镁合金牺我阳极保护Ａ３钢时,阴阳极之间的距离阴极保护时间及阳极数量对保护电位的影响。依据实验结果,对辽化某装置实施了阴极保护,取得了较好的效果。