摘要
通过电化学测试、XRD测试和密度泛函理论(DFT)计算,本文探讨了在不同pH值(12.4、12.9和13.5)的模拟混凝土孔隙溶液中Cl^(-)和SO_(4)^(2-)单独及共同作用对钢筋锈蚀行为的影响及其机制。结果表明:在pH值较低的饱和Ca(OH)2(CH)溶液中,当Cl^(-)浓度仅达到0.02mol/L时,开路电位(OCP)即由-375 mV急剧下降至-575 mV,表明Cl^(-)在低浓度情况下就会显著加速腐蚀;而在pH值较高的ST溶液中,随着腐蚀离子浓度从0.01 mol/L逐步增加至0.4 mol/L,钢筋的极化电阻(R_(p))从约100 kΩ·cm^(2)稳定下降至5 kΩ·cm^(2),但整体耐腐蚀性明显优于其他pH值的情况,显示了高pH值对腐蚀的有效抑制作用。此外,当Cl^(-)和SO_(4)^(2-)共存时,由于竞争吸附机制的作用,整体腐蚀速率介于两者单独存在时之间,SO_(4)^(2-)的存在一定程度上减缓了Cl^(-)引发的腐蚀。本文基于上述结果提出了一个竞争吸附-催化腐蚀的两阶段反应模型,详细揭示了二者共同作用下的腐蚀行为,Cl^(-)通过破坏钝化膜加速腐蚀进程,SO_(4)^(2-)则通过影响腐蚀产物的稳定性和分布参与腐蚀过程。
Through electrochemical tests,XRD analysis,and density functional theory(DFT)calculations,this study investigated the individual and combined effects of Cl^(−)and SO_(4)^(2-)ions on the corrosion behavior of steel reinforcement in simulated concrete pore solutions at different pH values(12.4,12.9 and 13.5).The results reveal that in the lower pH CH solution,even at a Cl^(−)concentration of only 0.02 mol/L,the open circuit potential(OCP)drops sharply from−375 mV to−575 mV,indicating significant acceleration of corrosion by Cl^(−)at low concentrations.Conversely,in the higher pH ST solution,as the concentration of corrosion ions increases gradually from 0.01 mol/L to 0.4 mol/L,the steel’s polarization resistance(R_(p))stabilizes and decreases from approximately 100 kΩ·cm^(2)to 5 kΩ·cm^(2),demonstrating superior overall corrosion resistance compared to lower pH conditions,highlighting the effective inhibition of corrosion at higher pH value.Furthermore,in the presence of both Cl^(−)and SO_(4)^(2-)ions,the overall corrosion rate lies between the rates observed when each ion is present individually,due to the competitive adsorption mechanism.The presence of SO_(4)^(2-)mitigates to some extent the corrosion initiated by Cl^(−).Based on these findings,the study proposes a two-stage competitive adsorption-catalytic corrosion reaction model,elucidating in detail the corrosion behavior under their combined influence:Cl^(−)accelerates corrosion by disrupting the passive film,while SO_(4)^(2-)participates in the corrosion process by influencing the stability and distribution of corrosion products.
作者
李嘉伦
刘国建
佘伟
刘志勇
张宇
张云升
LI Jialun;LIU Guojian;SHE Wei;LIU Zhiyong;ZHANG Yu;ZHANG Yunsheng(School of Civil Engineering,Suzhou University of Science and Technology,Suzhou 215011,China;School of Materials Science and Engineering,Southeast University,Nanjing 211189,China;School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China)
出处
《复合材料学报》
北大核心
2025年第5期2775-2787,共13页
Acta Materiae Compositae Sinica
基金
国家自然科学基金(52008284)。
关键词
腐蚀
氯盐
硫酸盐
PH
机制
corrosion
chloride
sulfate
pH
mechanism
