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构建了埋地管线表面剥离高绝缘性聚乙烯(PE)涂层下模拟缝隙实验装置,采用微电极技术研究阴极保护(CP)水平和环境气氛(CO2和O2)条件下剥离涂层下缝隙薄液电化学环境(电位和溶液pH值等)特征及其演化规律,探讨剥离涂层下近中性pH环境存在条件.结果表明,不同阴极保护水平和CO2分压条件下,剥离涂层下可出现近中性到高pH值各种薄液环境.高阴极保护电流使管表产生并维持高pH环境;大面积剥离、阴极保护屏蔽或缺失和CO2的缓冲作用可使剥离涂层下封存近中性pH应力腐蚀开裂(SCC)敏感薄液环境;由剥离涂层下缝隙薄液pH值可判断剥离涂层下阴极保护有效性及其屏蔽程度.
A simulated gap experimental device with high insulation polyethylene (PE) coating on the surface of buried pipeline was constructed. The micro-electrode technology was used to study the effects of cathodic protection (CP) level and environmental atmosphere (CO2 and O2) Liquid electrochemical environment (potential and solution pH value) characteristics and evolution of the stripping coating to explore the existence of near neutral pH conditions.The results show that under different levels of cathodic protection and CO2 partial pressure conditions, the stripping coating can be Appear near neutral to high pH value of a variety of thin liquid environment.High cathodic protection current tube table to produce and maintain a high pH environment; large area stripping, shielding or missing cathodic protection and CO2 buffer can peel coating Neutral pH stress corrosion cracking (SCC) sensitive thin-film environment; the effectiveness of the cathodic protection and the degree of shielding under the peeled-off coating can be judged by the pH value of the thin liquid under the peeling coating.