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3PE防腐蚀层联合阴极保护对管道的保护效果 总被引:1,自引:0,他引:1
采用阴极保护联合3PE防腐蚀层的方法对埋地钢质管道进行了防护。试验模拟了管道3PE防腐蚀层底漆存在、金属基体暴露、金属暴露孔处未与土壤介质接触及与土壤介质完全接触的不同情况,探讨了阴极电流与通电电位之间的关系,研究了通/断电位的负移对试样3PE防腐蚀蚀层阴极剥离的影响。结果表明,试样阴极保护电流的变化与管道3PE防腐蚀层的缺陷存在、土壤接触方式、通电电位密切相关。通/断电电位正于-0.85V(CSE)时,难以阻止试样发生腐蚀,通/断电位过度负移将造成3PE防腐蚀层的阴极剥离,使3PE防腐蚀层提前失效。 相似文献
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含重铬酸根硫酸溶液中磁场对铁自腐蚀状态及极化电阻的影响 总被引:3,自引:0,他引:3
铁在含有一定浓度重铬酸根的硫酸中,自腐蚀状态下的阴极反应速率受重铬酸根阴极还原电子转移过程与扩散过程共同控制.外加磁场使铁的自腐蚀电位正移,且电位正移幅度随重铬酸根浓度增加而增大.在没有外加磁场时的自腐蚀电位下进行恒电位极化时,外加磁场后会出现阴极电流,磁致阴极电流随重铬酸根的浓度增大而显著增大.外加磁场会使含有一定量重铬酸根的硫酸溶液中铁的极化电阻显著下降.通过对磁场作用进行模型化,分析了磁场作用的动力学机理.磁场对阴极扩散过程的加速作用导致了自腐蚀电位正移及磁致阴极电流,而磁场引起自腐蚀电位的正移是引起极化电阻减小的主要原因. 相似文献
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为了研究3PE防腐蚀层服役过程中的失效问题,采用现场测试、实验室分析和模拟试验等方法对服役中3PE防腐蚀层的剥离问题进行了分析,并对其寿命进行了预测。结果表明:生产过程中表面处理、环氧粉末喷涂等工艺控制不当,服役过程中防腐蚀层破损、阴极保护电位过负等环境因素,均会导致3PE防腐蚀层的剥离;同样的电流密度下,随着时间的延长,阴极剥离距离逐渐增加,且在试验前期增加较快,在试验后期增加变缓;相同时间下,施加的电流密度越高,阴极剥离距离越大,3PE防腐蚀层的特征寿命与电流密度的倒数呈指数关系。 相似文献
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《腐蚀工程科学与技术》2013,48(7):267-269
AbstractThe effect of cathodic protection on intermittently immersed water-line areas has been studied. Corrosion was greatly reduced in sea water compared with that in sodium chloride solution, and the degree of protection was greater at higher frequencies of immersion. The protective effect of cathodically deposited ‘chalk’ is discussed. No corrosion occurred at a static water-line in sodium chloride solution. 相似文献
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Cathodic arc deposition is a unique technology. An arc spot on a cathode generates a plasma consisting of cathode material with a high degree of ionization. The high concentration of ions allows control of film morphology, high adhesion, efficient reactive deposition of compounds and uniform deposition over a variety of shapes. The composition of the alloys is generally retained from source to substrate. Deposition rates cover a wide range from nanometers per minute to tens of micrometers per minute. Many aspects of the technology warrant further study and its applications are only just beginning. 相似文献
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Cathodic corrosion, particularly alkaline pitting and repassivation, of 1S aluminium has been investigated by potential-controlled methods in unbuffered chloride media. The results are mainly for de-aerated solutions; the influence of dissolved oxygen and stirring, which are likely to be present in a practical situation, are also discussed. The metal undergoes stable pitting and then uniform etching as the applied potential is decreased below ? 1.35 V(SCE). At potentials more positive than this threshold value, metal dissolution still occurs possibly near the cathodic impurities on the surface due to local alkalinization resulting from hydrogen evolution; but, the surface repassivates slowly as the cathodic sites are covered up by the oxide film. The polarization behaviour of the partially passive surface is studied by fast-scan potential measurements and is associated with hydrogen evolution kinetics. The measured current decays exponentially with time during repassivation at constant potential. This is explained in terms of a model based on film growth controlled by metal dissolution. 相似文献