共查询到17条相似文献,搜索用时 62 毫秒
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通过电化学测试和宏观形貌分析,研究了剥离涂层下机坪管道用L245管线钢在不同缝隙深度处的腐蚀行为。结果表明:剥离涂层下不同位置L245钢电极自腐蚀电位的大小与缝隙深度有关;距破损点90 mm处钢电极腐蚀速率有先下降后回升而后再下降的显著变化,并且出现了warburg阻抗扩散弧和明显的弥散效应,是该腐蚀体系下缝隙腐蚀最明显的一个点;距破损点90 mm处钢电极表面腐蚀产物层有明显裂纹,150 mm处钢电极表面点蚀情况突出;涂层剥离会造成L245管线钢缝隙腐蚀,在机坪管道防护中应引起重视。 相似文献
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碱性条件下碳钢的缝隙腐蚀行为 总被引:2,自引:0,他引:2
采用动电位扫描法研究了碱性条件下氯离子浓度、pH值、PO43-和NO2-两种缓蚀性离子对Q235钢缝隙腐蚀行为的影响.研究表明,碱性条件下氯离子对缝隙腐蚀有极强的促进作用,溶液pH值变化对缝隙腐蚀影响较小,PO43-对缝隙腐蚀可以起到抑制作用,并且PO43-的缓蚀作用明显大于NO2-. 相似文献
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钛缝隙腐蚀行为的研究 总被引:1,自引:0,他引:1
一、前言钛的缝隙腐蚀是钛材推广使用中最令人关注的问题之一。近二十年来,人们曾不同程度地研究过pH值、温度、氯化物浓度、缝隙尺寸等因素对钛缝隙腐蚀的影响,并根据各自的实验结果,提出了不同的缝隙腐蚀机理。主要的有“氧浓差说”、“Ti(Ⅲ)和Ti(Ⅳ)离子影响说”、“水份不足说”等观点。目前,多数人仍采用经典的夹片试验研究钛的缝隙腐蚀,对于缝隙腐蚀发生与发展过程中缝内介质组份的变化及其物理、化学图象还缺乏直接的现场信息。鉴于此,本文用微电极技术原位考察了热酸性氯化钠溶液中的钛缝隙腐蚀行为及其影响因素,提出了其机理。 相似文献
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目的 明确交流杂散电流对埋地管线防腐层剥离和破损处防腐层下腐蚀的影响规律及其导致防腐层剥离的作用机理。方法 通过基于COMSOL Multiphysics有限元仿真、交流阻抗谱分析及三维体式显微镜观测等方法,研究在格尔木土壤模拟溶液中,交流杂散电流干扰下,X70钢表面3PE防腐层剥离处的防腐层下腐蚀及剥离机理。结果 由于防腐层破损点和剥离区域的存在,使得防腐层的防护性能明显降低,交流杂散电流在初始预留剥离处的X70钢表面呈不均匀分布,破损点处所分布电流密度明显高于剥离区边缘处。杂散电流引起的腐蚀反应主要集中在防腐层破损点处,而处于预留剥离区域下方的X70钢表现出缝隙腐蚀的现象。防腐层破损点处的腐蚀坑深度随电流密度的增加而逐渐变深,而当交流电流密度由0 A/m2增加到100 A/m2时,防腐层剥离面积明显增大,此后,当电流密度继续增大,剥离面积基本保持不变。当施加的交流电流密度相同时,随着防腐层剥离面积的减小,杂散电流造成的防腐层剥离面积增大,X70钢试样上的最大腐蚀坑略微加深。结论 造成防腐层剥离的交流杂散电流存在临界电流密度值,使得防腐层剥离面积达到最大且之后保持不变。防腐层初始剥离面积较小时,交流电所造成的X70钢腐蚀及防腐层剥离行为更为严重。 相似文献
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缝隙腐蚀研究进展及核电材料的缝隙腐蚀问题 总被引:2,自引:0,他引:2
综述了缝隙腐蚀的主要机理、模拟研究技术及影响因素,介绍了核电材料在实际服役过程中的缝隙腐蚀问题,讨论了高温高压水环境下缝隙腐蚀研究存在的主要问题以及进一步的研究方向。 相似文献
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钛的缝隙腐蚀行为研究 总被引:3,自引:0,他引:3
梁成浩 《稀有金属材料与工程》1994,23(6):41-44
采用电化学测试技术,研究了工业纯钛和Ti-0.3%Mo-0.8%Ni合金在25%NaCl和HCl沸腾溶液中的缝隙腐蚀行为。结果表明,由于合金元素Ni具有低的氢超电势,促进了阴极极化过程,从而提高了钝化能力,且缝内表面Ni的富集增强了膜的钝化稳定性,因此,Ti-0.3%Mo-0.8%Ni合金抗缝隙腐蚀性能优于工业纯钛。 相似文献
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Carbon dioxide corrosion behavior of low-alloy pipeline steel with 1% Cr exposed to CO2-saturated solution was investigated by immersion experiment. SEM, EDX, TEM, EPMA and XRD were utilized to investigate the microstructure, corrosion morphologies, corrosion phases and elements distribution of corrosion scale. The results demonstrate that the microstructure of tested steel consists of ferrite and carbides. During the corrosion process, ferrite dissolves preferentially, leaving carbide particles behind. The residual carbide particles may promote the nucleation of FeCO3 crystal. The phase comprising of the inner layer is Cr compound, and the one of the outer layer is FeCO3. The formation process of corrosion scale can be illustrated as follows: Firstly, a thin scale consisting of thin inner layer and outer layer is formed, which represents poor corrosion resistance; then, the inner layer changes little, once it has been formed, and the outer layer becomes thick and compact, which demonstrates that a fine corrosion resistance is obtained. The chemical elements of chromium and molybdenum accumulate in the inner layer of corrosion scale. The corrosion behavior of low-alloy steel based on microstructure and morphology characterization is also discussed. 相似文献
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Erfan Abedi Esfahani Hamidreza Salimijazi Mohamad A. Golozar Javad Mostaghimi Larry Pershin 《Journal of Thermal Spray Technology》2012,21(6):1195-1202
In the current study, aluminum coating was deposited on mild steel by arc spraying. A well-adhered coating with low level of porosity was successfully obtained. To evaluate the corrosion behavior of the coating, electrochemical impedance spectroscopy (EIS) and polarization tests in 3.5% NaCl solution were carried out. The as-coated samples were also subjected to a 1500-h salt spray assay. Polarization tests indicated that the corrosion current density of the aluminum coating is more than that of bulk aluminum. This could be due to the penetration of the electrolyte through open pores, resulted in the acceleration of aluminum corrosion. EIS measurements showed that the corrosion performance of the coating is improved during a long time immersion and exposure to saline mist. This could be due to plugging of pores by corrosion products which hinder further penetration of the electrolyte through the coating. The results obtained indicated that twin wire arc sprayed aluminum coatings can reliably protect steel structures against corrosion in chloride-containing aqueous solutions. 相似文献