电化学噪声技术在铝合金大气腐蚀检测中的应用

基于电化学噪声（EN）技术建立了适合现场应用的铝合金大气腐蚀测量系统。研制了铝合金大气腐蚀传感器,构建了零阻电流（ZRA）模式的EN测量系统和软件。利用该系统在实验室模拟和户外大气环境下进行了EN测试,研究结果表明,通过电位和电流噪声信号及噪声电阻变化可以对铝合金大气腐蚀过程进行有效检测。     

新型腐蚀电化学传感器在金属材料大气腐蚀现场检测中的应用

研制了适用于金属材料大气腐蚀监检测的电化学传感器,通过电化学噪声技术研究Q235B和T91钢在舟山海洋大气中的腐蚀电化学行为,利用电位/电流标准偏差或噪声电阻值的变化得到表征金属材料大气腐蚀过程的特征参数。结果表明,该传感器可成功实现钢铁材料大气腐蚀的实时在线监检测。均匀腐蚀过程的电流噪声标准偏差和噪声电阻值的变化与腐蚀速率有直接关系;局部腐蚀过程中电流噪声标准偏差的变化一定程度上可反映腐蚀速率的变化,但噪声电阻值与腐蚀速率并无直接关系。     

水环境中焊接件腐蚀电化学传感器的研制

研制了一种可用于检测水环境中焊接件焊缝与母材不同部位腐蚀状况的电化学传感器,分别设计了适合对接和角接焊缝腐蚀检测的两种传感器.运用局部封闭原理,测试时传感器与待测构件表面形成临时封闭的电解池.利用磁铁将传感器固定在待测件表面.实验验证了封闭电流的能力.并应用所研制的传感器对3.5%NaCl溶液中模拟焊接试样的焊缝及母材不同部位进行了测试.结果表明,焊缝和母材的极化阻力随时间呈现出不同的变化规律,EIS测试结果也存在明显的区别.结果表明,研制的传感器可以很好地区分出焊接件不同部位的腐蚀状况.     

316L不锈钢在FeCl3溶液中点蚀行为的电化学噪声检测

利用电化学噪声技术检测了316L不锈钢在6％FeCl3溶液中点蚀的电化学噪声谱,观测腐蚀形貌,分析电化学噪声谱特征参数。结果表明,在浸泡初期,电流噪声波动较小,有暂态峰出现,电流功率谱密度（PSD1）的斜率变化不大,表明电极表面出现亚稳态蚀点,钝化膜溶解与修复交替进行。在腐蚀后期,PSD1出现高频白噪声水平,电流噪声波...     

2205双相不锈钢和304不锈钢在氢氟酸溶液中缝隙腐蚀敏感性比较

采用缝隙腐蚀试样,通过浸泡实验以及循环极化、电化学阻抗、电化学噪声、恒电位测试等电化学方法,研究了2205双相不锈钢(2205DSS)和304不锈钢(304SS)在5%(质量分数)氢氟酸溶液中的缝隙腐蚀行为。结果表明,两种不锈钢在氢氟酸溶液中都发生了缝隙腐蚀,但2205双相不锈钢腐蚀形成的蚀坑较浅,而304不锈钢腐蚀形成的蚀坑较深,且腐蚀面积更大。电化学测试结果表明,2205DSS的临界缝隙腐蚀电位E_(crev)和再钝化电位E_(rp)都高于304SS的,滞后环的面积也更小,钝化膜电阻和缝隙腐蚀发生时的电荷转移电阻也更大。2205DSS的白噪声水平更小,缝隙腐蚀反应更慢。同时,在相同外加电位下,2205DSS的缝隙腐蚀诱导期更长,缝隙腐蚀发生时电流更小,2205DSS的抗缝隙腐蚀能力优于304SS,这主要与两种材料表面所成钝化膜的组成和性能不同有关。     

2B06铝合金大气腐蚀过程的电化学噪声监测

采用电化学噪声EN（electrochemical noise）技术和基于Compact RIO的分布式大气腐蚀便携式现场实时监测系统,对北京地区大气环境下2B06铝合金腐蚀过程进行长期监测,并对采集的电化学噪声信号进行统计分析,探索了电化学噪声方法在铝合金腐蚀现场监测方面的应用及腐蚀速率表征参数,从而对腐蚀进行预测并减小损失。结果表明：该系统可对铝合金的大气腐蚀过程进行现场实时监测,电化学噪声电阻Rn和电流噪声标准偏差SI可作为反映铝合金大气腐蚀速率的表征参数;长期监测结果显示北京地区的2B06铝合金在相对干燥的秋冬季节腐蚀较缓。     

海洋金属腐蚀监检测电化学传感器的研制

研制了一种适用于材料海水腐蚀试验站网金属挂片腐蚀检测的电化学传感器,设计了弹性固定装置,并应用所研制的传感器,对于碳钢试片在35%NaCl溶液中进行了测试,结果表明,传感器能够如实地反映试     

敏化态304不锈钢慢速率拉伸腐蚀过程的电化学噪声检测

采用电化学噪声方法对敏化态304不锈钢在0．5mol／LNa2＆O3溶液的慢速率拉伸过程的腐蚀进行检测,同时得到腐蚀过程的电位与电流变化曲线,试验后试样表面出现了多处应力腐蚀裂纹。分别采用时域谱、频域谱及小波分解分析电流噪声数据,表明腐蚀过程经历了应力腐蚀裂纹萌生与裂纹扩展的过程。根据多种电化学噪声谱图及小波分解后的能...     

模拟海洋环境浪花飞溅区的金属构筑物腐蚀监检测

建立了实验室模拟海洋环境腐蚀试验装置,可以模拟浪花飞溅区、海水潮差区、海水全浸区等多种海洋腐蚀环境。研制了一种可用于浪花飞溅腐蚀监检测的电化学传感器,利用该传感器测试了模拟腐蚀试验架浪花飞溅部位的电化学噪声特征,分析比较了不同部位噪声电阻R_n值,表明涂覆清漆的部位耐蚀性能优于裸露部位。     

表面粗糙度对304不锈钢早期点蚀行为影响的电化学方法

采用动电位扫描、电化学阻抗谱和电化学噪声等方法研究了4种不同表面粗糙度304不锈钢电极在质量分数为3％的NaCl溶液中的早期腐蚀行为.随着不锈钢电极表面粗糙度的下降,304不锈钢自腐蚀电位与点蚀电位均有所上升;电荷转移电阻噪声电阻明显升高,而电位标准偏差与电流标准偏差则有所降低;粗糙度0.25μm的电极在阻抗谱低频区出...     

Field Corrosion Detection of Nuclear Materials using Electrochemical Noise Techinique

Some critical issues when applying electrochemical noise (EN) in field corrosion detection of nuclear materials are solved. In this work, a portable EN measurement system for field test is established by using Compact RIO modular instrument and zero resistance ammeter (ZRA) module. The electrode system for EN measurement is built by using platinum wire or stainless steels coated with thermal sprayed ceramic coatings as counter electrode. Two EN sensors are developed based on the electrode system mentioned above, and field corrosion detection is successfully achieved. The corrosion of stainless steel pipeline surface in nuclear power plant and internal-surface corrosion of continuous blowdown piping are successfully evaluated by the established new EN measurement system.     

滨海电厂水系统碳钢管道的腐蚀控制

针对某滨海电厂海水及海水反渗透产水管道的腐蚀现象,采用失重法、扫描电镜、X射线衍射及电化学测试,对比研究了碳钢在其中的腐蚀差异。结果表明:在海水中锈层抑制氧的传递,对碳钢起保护作用;在反渗透产水中锈层起大阴极作用,加速基体腐蚀。实际工程中,海水反渗透产水比海水对碳钢管道更具侵蚀性。重新矿化反渗透产水是降低其腐蚀性的有效方法;另外,可考虑采用更耐蚀的不锈钢、碳钢衬塑管等作为管材。     

Application of LPR and EIS techniques for on-site corrosion monitoring at the geothermal plant in Central Poland

Corrosion monitoring station was installed at ‘Geotermia Mazowiecka’ geothermal plant in Poland. Linear polarisation resistance and electrochemical impedance spectroscopy techniques were applied to estimate the corrosion rate and the surface changes of K55 carbon steel, L80-13CR and 316 stainless steels directly in the geothermal water flux. The enhanced corrosion of K55 carbon steel and corrosion rate of L80-13CR and 316 stainless steels was observed. The formation of biofilm increased the resistivity of the surface.     

Monitoring localised corrosion in inhibited solutions using wire beam electrode–noise signatures method

Abstract

The objective of this work is to determine the nature of localised corrosion in inhibited solutions by establishing possible relationships between characteristic features in electrochemical noise and corrosion processes using an electrochemically integrated multielectrode system, namely the wire beam electrode (WBE) in combination with noise signatures method. Experiments have been carried out to simultaneously measure electrode potential noise and WBE current distribution maps from stainless steel (SS316L) WBE exposed to inhibited solutions containing 6%FeCl₃ solution with inorganic inhibitors including 2 wt-% sodium chromate (Na₂CrO₄), cerium chloride (CeCl₃) and lanthanum chloride (LaCl₃). Characteristic electrochemical noise signatures were found to correlate with characteristic changes in WBE current distribution maps that show corrosion rates distributions and the degree of localised corrosion. A new concept namely localisation parameter (LP) has been proposed to identify the degree of inhibition. Na₂CrO₄ effectively inhibited the pitting corrosion process and the LP successively decreased through out the corrosion process. With the presence of CeCl₃ and LaCl₃, pits on stainless steel in 6%FeCl₃ solution were not repassivated and an increase in the LP was observed for both inhibitors. The results suggest that the WBE method could be used in combination with the noise signatures as a sensitive technique for monitoring inhibiting effect on localised corrosion.     

An electrochemical study of the corrosion behaviour of metals in canola biodiesel

The corrosion behaviour of pure Al, Cu, 1018 carbon steel and 304 type stainless steel in Canola biodiesel during 528 hours has been evaluated by using electrochemical techniques. Techniques include open circuit potentials (OCP), electrochemical noise (EN) and electrochemical impedance spectroscopy (EIS) measurements at room temperature. These tests were complemented by scanning electronic microscopy, X-ray diffraction, infrared spectroscopy and gas mass chromatography analysis. Results have shown that carbon steel had the highest corrosion rate whereas Cu had the lowest corrosion rate. EN measurements indicated that 304 type stainless steel was moderately susceptible to pitting corrosion, whereas the rest of the metals were susceptible to either mixed or uniform type of corrosion. This was due to the degradation of the biodiesel as observed in an increase in its density, viscosity, acidity and water content at the end of the test.     

核电站主回路大厚度不锈钢管道的焊接

简要介绍了核电站主回路大厚度不锈钢管道的焊接工艺,在核电站建设中,接触高温强腐蚀或化学强腐蚀介质的管道常用奥氏体不锈钢制造。核电站主回路中的介质含有高放射性物质,焊接质量的好坏将直接影响到机组的安全运行。     

核电厂管道及焊接接头失效案例综述

通过收集近年来发生的200多起核电设备失效案例并整理分析,对核电设备失效的基本现状进行统计归纳,主要针对碳钢、不锈钢管道及焊接接头进行失效模式、原因、机理的统计分析。从整体的失效情况来看,腐蚀失效是核电站主要设备比较突出的失效问题;核电管道约80％的失效形式是局部腐蚀和振动疲劳,核岛、常规岛和海水系统的碳钢与不锈钢管道因材质、作用等差异,失效的具体形式也有所不同;应力腐蚀开裂是焊接接头的主要失效形式。     

Detection of SCC initiation in austenitic stainless steel by electrochemical noise measurements

The electrochemical noise (EN) measurement technique is one of the most promising tools for continuous in situ corrosion monitoring in technical systems with a certain potential to be used for the detection of stress corrosion cracking (SCC). To evaluate the suitability of the EN technique for the detection of SCC initiation, a small but systematic test programme was started, performing EN measurements on type 304 austenitic stainless steel during constant extension rate tensile tests in aqueous thiosulphate solution at room temperature. SCC could be detected by EN measurements, which was verified by interruptions of the experiments at different stages, by testing steel with different degrees of sensitisation and by post‐test fractography in the scanning electron microscope. Conclusions on the cracking mechanism could be drawn based on the current noise signal pattern.     

奥氏体不锈钢铁污染的来源以及防护措施

奥氏体不锈钢作为核工业的重要钢材,其必须具有非常优良的耐腐蚀性能.然而在核主泵的生产流程中不规范的加工、运输以及安装会使奥氏体不锈钢的耐腐蚀性能降低,其中最严重之一的影响因素就是奥氏体不锈钢的铁污染.为使奥氏体不锈钢达到生产核电设备的严格要求以及核电站能够安全运行[1],对奥氏体不锈钢铁污染的来源的掌握很重要.本文对污染源进行总结,并针对不同污染源阐述了相应的防护措施.