阵列电极在腐蚀电化学中的应用

阵列电极技术是一种新兴的电化学研究技术,在各个领域都有广泛的应用。本文论述了阵列电极的发展与其在腐蚀电化学中的应用,重点论述了其在大气腐蚀下的应用,并对其未来发展进行了展望。     

Studies on waterline corrosion processes and corrosion product characteristics of carbon steel in 3.5 wt% NaCl solution

The waterline corrosion behaviors of carbon steel partially immersed in a 3.5 wt% NaCl solution were investigated using the wire beam electrode technique, and the effects of corrosion products on the processes of waterline corrosion were analyzed. The results demonstrated that the initial stage and development stage of waterline corrosion were mainly controlled by the concentration and diffusion of dissolved oxygen, respectively, and the deceleration stage of waterline corrosion was mainly affected by corrosion products. The main component of the yellow corrosion products was γ-FeOOH, and γ-FeOOH that exhibited a high reduction reactivity could be involved in the cathodic reaction. The black corrosion products were mainly composed of Fe₃O₄ with strong thermodynamic stability and the processes of dissolved oxygen diffusion and ion transports were obviously affected due to the continuous accumulation of Fe₃O₄ on the surface of the electrodes. Polarity reversals were observed on the single electrodes below the waterline, but the reasons for the phenomena were different from each other.     

六亚甲基二异氰酸酯微胶囊的制备及其在自修复涂料中的应用

目的 制备一种基于小尺寸六亚甲基二异氰酸酯(HDI)微胶囊的自修复防腐涂料,能够提高涂层的防腐性能并实现涂层划痕缺陷的在线修复。方法 通过调整界面聚合法合成HDI微胶囊过程中的乳化剂添加量、搅拌速率和体系pH值,降低微胶囊的平均粒径,并利用囊芯染色试验、红外光谱(FTIR)、热重试验(TG)对微胶囊的结构和热稳定性进行表征。以物理共混的方式将微胶囊掺入到环氧树脂基质中制备自修复防腐涂料,使用万能拉伸机、拉拔测试仪、电化学阻抗谱(EIS)研究微胶囊对涂层基础力学性能和耐腐蚀性能的影响。结合丝束电极(WBE)测试与划痕涂层浸泡腐蚀试验分析复合涂层的内在自修复机理。结果 确定了微胶囊制备过程的最佳乳化剂添加量为3%、搅拌速率为600 r/min、体系pH值为3.5,此时的微胶囊呈规则的球状结构,表面致密且具有一定的粗糙度,平均粒径尺寸降低为59μm,成型率达82%。FTIR和囊芯染色试验证明微胶囊由脲醛树脂囊壁和HDI囊芯组成,TG分析显示微胶囊初始分解温度为260℃。随着微胶囊含量的提高,自修复涂层的拉伸断裂强度和附着力有所下降。EIS测试结果表明,含0%、1%、5%和10%微胶囊的自修复...     

苯并三唑对碳钢/铜合金电偶腐蚀行为的影响

目的 研究NaCl溶液中苯并三唑(BTA)对碳钢/铜合金电偶腐蚀行为的影响.方法 使用丝束电极(WBE)技术和电化学阻抗谱(EIS)技术研究在未添加和添加BTA的NaCl溶液中,丝束电极表面的电位分布、电流密度分布和电化学阻抗谱演化,同时对比分析碳钢区域与铜合金区域的阻抗谱特征.结果 在未添加BTA的条件下浸泡72 h...     

利用WBE及EIS测试技术对管道缺陷区动态冲刷腐蚀行为的研究

油气管道内缺陷的存在会使油气输运过程中出现局部区域流体急剧变化,导致管道腐蚀失效。本文通过微电极阵列测试技术(WBE)以及宏观电化学测试技术(EIS)研究管道缺陷处的冲刷腐蚀行为,以COMSOL Multiphysics中的流体力学模块辅助分析缺陷不同区域在流动状态下的腐蚀机制。结果表明,缺陷不同区域之间的流场变化导致腐蚀差异性,紧邻缺陷的上缘与下缘区域承受较大的湍流动能及壁面剪切力表现为阳极,腐蚀较为严重;缺陷底层区域以及远离缺陷两侧的区域由于湍流动能较小而边界层厚度大,离子传质作用较弱,表现为阴极,缺陷底层区域相比于缺陷上下缘区腐蚀进行缓慢。随着流动腐蚀时间的延长,缺陷上下缘区域腐蚀更为严重,缺陷整体有沿深度方向扩展加深的趋势。     

Understanding electrodeposition of polyaniline coatings for corrosion prevention applications using the wire beam electrode method

Polyaniline (PANI) films have been successfully electrodeposited on aluminium AA1100 electrode surfaces in acidic electrolytes as anti-corrosion coatings. The wire beam electrode (WBE) has been applied for the first time as a novel tool to monitor the electrodeposition processes; and also to understand the anti-corrosion performance and mechanism of the PANI coatings. During PANI electrodeposition, the WBE was polarised anodically, and anodic polarisation currents were measured from various locations over the WBE surface to produce anodic polarisation current maps (APC maps). Preliminary experiments have revealed that if an AA1100 electrode was not pre-treated, APC maps would show a localised anodic current distribution, resulting in a nonuniform PANI deposit. If the AA1100 electrode was pre-treated by a cathodic polarisation process, APC maps would show a random anodic current distribution, leading to a PANI coating covering the whole electrode surface. When exposed to a corrosive environment, PANI coatings were found to prevent localised corrosion of AA1100, primarily by enhancing its passive film rather than by a barrier mechanism. However, a nonuniform PANI coating has been found to accelerate general corrosion of AA1100. These results suggest that the WBE is a practical tool for monitoring, characterising and optimising PANI electrodeposition processes and for evaluating the anti-corrosion performance of PANI coatings.     

用丝束电极(WBE)评价不锈钢在NaCl溶液中点蚀敏感性

用丝束电极作为参比或辅助电极，测量不锈钢材料在不同氯化物浓度溶液中的表面性质差异．发现表面电极电位、电偶电流和交流阻抗测量数据极差和环境氯离子浓度对数均呈良好线性关系．可作为评价材料点蚀敏感性指标，要比传统指标(如点蚀电位和阳极极化曲线滞后环面积等)更加优越．此外，基于自然浸泡试件的材料表面电位极差一时间曲线，可用丝束电极研究材料的点蚀潜伏期．     

An Algorithm for Obtaining Welch Bound Equality Sequences for S-CDMA Channels

In this paper we describe the properties of those sequences(matrix) that meet equality in the Welch's lower bound on total squared correlation. These sequences are called also Welch Bound Equality (WBE) sequences. The generalized WBE sequences (matrix) are defined. Same definitions on majorization are introduced in order to characterize the eigenvalues of a hermitian matrix. A new algorithm for generating WBE spreading sequence multisets is proposed. We apply the proposed algorithm when all users have different average-channel-input energy constraint in the case of synchronous CDMA channels. We obtain real optimum signature sequences that maximize the sum capacity of S-CDMA channels.