碳酸化孔隙液中2304不锈钢的自然钝化及点蚀行为  

Natural passivation and pitting behavior of 2304 stainless steel in carbonized porous fluid

作　　者：陈浩东 邹德宁[1] 陈兴润[2] 钱张信[2] 李雨浓 李苗苗 CHEN Haodong;ZOU Dening;CHEN Xingrun;QIAN Zhangxin;LI Yunong;LI Miaomiao(School of Metallurgical Engineering,Xi′an University of Architecture and Technology,Xi′an 710055,Shaanxi,China;Hongxing Iron and Steel Co.,Ltd.,Jiuquan Iron and Steel Group Corporation,Jiayuguan 735100,Gansu,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055 [2]酒钢集团宏兴钢铁股份有限公司,甘肃嘉峪关735100

出　　处：《钢铁》2023年第12期128-136,共9页Iron and Steel

基　　金：国家自然科学基金资助项目(52271067)。

摘　　要：混凝土的碳酸化是钢筋混凝土(RC)结构主要的失效形式之一,更有甚之在沿海、寒冷地区等苛刻环境下使用除冰盐时,RC结构还会受到碳酸化及氯化物侵蚀的协同作用,导致使用寿命大幅降低。为此,分别对混凝土的碳酸化以及碳酸化和氯化物协同引起的不锈钢失效行为进行专门研究。通过浸泡试验、电化学阻抗谱(EIS)、X射线光电子能谱仪(XPS)、动电位循环极化(CPP)等方法研究了碳酸化孔隙液中2304不锈钢的自然钝化及点蚀行为,采用扫描电镜(SEM)及能谱仪(EDS)分析其腐蚀后形貌。结果表明,2304双相不锈钢在模拟混凝土孔隙液(pH13.34)中浸泡9 d后,频率为0.01 Hz的阻抗模值|Z|_(f=0.01Hz)随浸泡天数增加而不断升高,由3.20×10^(5)Ω上升至1.01×10^(6)Ω,表明试验钢在该溶液下可以自然钝化形成钝化膜;在不同碳酸化程度(pH13.34、pH11.00、pH9.67)下浸泡9 d的试验结果表明,随溶液pH值降低,不锈钢|Z|_(f=0.01Hz)由1.02×10^(6)Ω减小至3.01×10^(5)Ω,试样表面钝化膜发生降解;XPS分析得知试验钢外层钝化膜主要以Fe^(3+)主导,内层以Cr(OH)_(2)为主,碳酸化会使外层钝化膜中Fe^(2+)与Fe^(3+)比例降低,而对内层钝化膜几乎无影响;在不同碳酸化程度的含3.5%NaCl模拟混凝土孔隙液中,试验钢的点蚀电位及再钝化电位由0.635 V和0.557 V提升至0.960 V和0.876 V;研究表明碳酸化使得2304不锈钢的耐点蚀能力增强,这归因于Cl-与HCO-3的竞争吸附作用,高浓度的HCO-3可以抑制点蚀发生,而点蚀主要在O-Al夹杂物处萌生。Carbonation of concrete is one of the main forms of failure in reinforced concrete(RC)structures,and even when deicing salts are used in harsh environments such as coastal and cold regions,RC structures are subject to the synergistic effect of carbonation and chloride erosion,resulting in a significant reduction in their service life.Therefore,specialized research is conducted on the carbonation of concrete and the failure behavior of stainless steel caused by the synergistic effect of carbonation and chloride.The natural passivation and pitting behavior of 2304 stainless steel in carbonized porous liquid were studied by immersion experiments,electrochemical impedance spectroscopy(EIS),X-ray photoelectron spectroscopy(XPS)and cyclic polarization of dynamic potential(CPP),and the post-corrosion morphology was analyzed by scanning electron microscopy(SEM)and energy spectroscopy(EDS).The results show that after soaking 2304 duplex stainless steel in simulated concrete pore solution(pH13.34)for 9 days,|Z|_(f=0.01 Hz),which is the impedance modulus with a frequency of 0.01 Hz,continuously increases with the number of immersion days,increasing from 3.20×10^(5)Ωto 1.01×10^(6)Ω,indicating that the test steel can naturally passivate and form a passivation film in this solution.The experimental results of soaking for 9 d at different degrees of carbonation(pH13.34,pH11.00,pH9.67)showed that as the pH value of the solution decreased,the stainless steel |Z|_(f=0.01 Hz) increased from 1.02×10^(6)Ωreduced to 3.01×10^(5)Ω,the passivation film on the surface of the specimen degrades.XPS analysis showed that the outer passivation film of the test steel is mainly dominated by Fe^(3+),and the inner layer was mainly composed of Cr(OH)_(2).Carbonation would reduce the proportion of Fe^(2+)to Fe^(3+)in the outer passivation film,while it had almost no effect on the inner passivation film.The pitting and repassivation potentials of the test steel were increased from 0.635 V and 0.557 V to 0.960 V and 0.876 V in simulated concre

关 键 词：双相不锈钢 模拟混凝土孔隙液 碳酸化 电化学 自然钝化 点蚀 

分 类 号：TG178[金属学及工艺—金属表面处理]