摘要
采用矩形缝隙装置,测量了模拟剥离涂层下不同位置X70钢的电位、溶液pH值及氧含量随时间的变化曲线.研究了外加阴极极化电位、涂层破损尺寸和缝隙厚度对X70钢在Na_2SO_4溶液中的缝隙腐蚀行为的影响.结果表明,缝隙内氧气迅速耗尽并使溶液pH值升高,氧耗尽与外加阴极极化电位无关.随着缝口阴极极化程度加大,缝隙内各点电位负移,有效保护距离增加.溶液介质电位(IR)降集中在缝口.极化程度过高会导致氢气的析出.减小缝隙厚度和破损点尺寸使缝隙内极化程度降低.
A rectangle crevice assembly was used to measure the change of potential of steel X70, pH value and oxygen content in the crevice with time under the simulated disbonded coating. The effects of cathodic polarization potential, crevice thickness, holiday size on the crevice corrosion behavior of steel X70 in Na2SO4 solution were investigated. It is found that the dissolved oxygen was depleted within the crevice and thus shifted the solution to a more alkaline state. The oxygen depletion has no relation with the applied potential. The potential of the steel reaches the protected potential range, pH value of the solution increases and the protection distance becomes longer when the applied cathodic potential is more negative. Overprotection would result in the hydrogen evolution. The potential drop （IR） of the solution mainly occurs in the vicinity of the opening. The polarization degree decreases the thinner or smaller holiday crevice.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第12期1431-1438,共8页
Acta Metallurgica Sinica
基金
国家科技部基础条件平台建设项目2005DKA10400~~
关键词
X70管线钢
阴极保护
缝隙腐蚀
电位分布
氧含量
PH值
pipeline steel X70, cathodic protection, crevice corrosion, potential distribution,oxygen content, pH value
