【作者】 韩磊；

【导师】 宋诗哲；

【作者基本信息】 天津大学 ， 应用化学， 2008， 博士

【摘要】 电化学方法在腐蚀监检测中具有无可替代的优势,虚拟仪器技术以用户自定义功能和软件化为主要特点,二者的结合使研究人员能够根据测试项目的需要,以较短的周期和较低的成本建立监检测系统,在实时在线腐蚀检测和监控领域有广阔的发展空间。本文工作依据国家材料自然环境腐蚀试验站网大气/海洋全浸区金属材料的腐蚀检测、核电结构材料早期局部腐蚀的电化学噪声检测、发电厂/变电站接地网腐蚀电化学检测等项目的实际需要,应用虚拟仪器技术和电化学方法构建测试系统开展研究。研制了基于电化学频率调制(EFM)技术的测试系统,能够实现EFM测试。通过实验室试验对EFM测试系统和实验技术进行了检验,证明系统能够有效地测得多种体系中的腐蚀速率等电化学动力学参数。研制了适合现场检测的实海金属试片腐蚀电化学测试系统,对舟山海洋腐蚀试验站全浸区Q235碳钢试片进行了线性极化阻力和EFM检测。EFM方法测得的极化阻力较传统线性极化阻力方法偏小,但能够直接得到腐蚀速率,可作为试验站一种备选的腐蚀电化学检测技术。研制了基于电化学噪声(EN)技术的测试系统和数据解析软件,并将其应用于铝合金大气腐蚀监测及核电结构材料的应力腐蚀开裂检测。获得了自然大气环境中铝合金大气腐蚀的电位电流噪声和噪声电阻变化,分析了表面完好的304奥氏体不锈钢和存在微裂纹的800镍基合金C型环试样在室温蒸馏水中的电化学噪声谱特征,初步证明EN技术可以对大气腐蚀及核电结构材料的局部腐蚀进行有效监检测,为进一步的研究提供了有力工具。研制了接地网腐蚀电化学检测系统和数据解析软件,通过恒电流阶跃测试得到接地网测试位置的极化阻力值作为表征腐蚀状况的参数。进行了现场试验,研究了检测传感器的限流效果,确定了适当的检测设备和数据解析方法。结果表明,小孔限流型传感器具有明显的限流效果,小波变换和Levenberg-Marquardt算法能够有效消除充电曲线数据中的噪声干扰和土壤电阻影响。接地网腐蚀电化学检测系统能够在现场提供有价值的信息,为接地网的腐蚀诊断提供依据。更多还原

【Abstract】 Electrochemical methods are irreplaceable in corrosion monitoring and detecting. Virtual instrument technology is characterized with self-defined function and software implementation. The combination of both technologies makes the researchers able to build measurement systems according to their special project with shorter development cycle and higher cost performance, and shows broad development space in the field of on-line and real-time corrosion detecting and monitoring. In the work of this dissertation, electrochemical methods and virtual instrument technologies were applied to build measurement systems to make a study of some practical projects: electrochemical measurements for atmospheric and marine corrosion of the metal coupons at natural environmental corrosion test stations of China, initial detection for local corrosion of the nuclear structural materials with electrochemical noise technique, and electrochemical detection for corrosion of the grounding grids at power plants and transform substations.A measurement system based on electrochemical frequency modulation (EFM) technique was developed, which could implement EFM measurement. The EFM system and EFM technique were examined by laboratory experiments and proved to be available to determine the electrochemical kinetic parameters like corrosion rate in various of corroding systems. A corrosion electrochemical test system for in-field detection of the metal coupons in natural sea was also developed, and was used to detect the corrosion of Q235 steel in fully immersion zone at Zhoushan marine corrosion test site with linear polarization resistance (LPR) and EFM measurement. The results showed that although the Rp obtained with EFM tended to be lower than its real value, corrosion rate was offered directly. Thus, EFM technique was shown to be a possible candidate for corrosion detecting and monitoring at the national corrosion test sites.A measurement system and data analysis software were developed based on electrochemical noise technique, which were applied to detect the atmospheric corrosion of aluminum alloy and the stress corrosion crack of nuclear structural materials. The electrochemical potential and current noise were acquired by aluminum alloy atmospheric corrosion sensor in natural atmosphere as well as the noise resistance. Characteristic of the electrochemical noise signals were analyzed for 304 austenitic stainless steel and 800 Nickel-based alloy C-ring specimens in distilled water at room temperature. It was initially verified that EN technique was effective to detect atmospheric corrosion and local corrosion of nuclear structural materials, which provide a powerful tool for further research.A measurement system and data analysis software were developed for grounding grid corrosion detection. Polarization resistances of the grounding grid at measured positions were obtained with galvanostatic measurement as an evaluating parameter for corrosion. In-field experiments were performed at several power plants and transform substations, through which the effect of the apertural current limit sensor, the proper test apparatus and data analysis method were studied. The results showed that the current flowing between working electrode and auxiliary electrode were limited in a certain area by the apertural current limit sensor, and the noise disturbance and the IR drop caused by soil resistance were well eliminated by wavelet transform and Levenberg-Marquardt algorithm respectively. The grounding grid corrosion electrochemical test system could provide useful information for grounding grid corrosion diagnosis.更多还原