摘要
目的 钼酸钠作为无机缓蚀剂的一种,因其价格低廉、无毒且环保而被广泛关注,重点研究了钼酸钠在含氯模拟混凝土孔隙液(SCPS)中对HRB400低合金钢(HRB400)的缓蚀行为。方法 采用浸泡试验、电化学阻抗谱和动电位极化曲线测试等方法评估钼酸钠的缓蚀性能和HRB400钢在不同浓度钼酸钠溶液中的临界Cl^(-)浓度;采用扫描振动电极技术(SVET)原位研究钼酸钠对HRB400钢腐蚀活性的影响;利用X射线光电子能谱(XPS)、原子力显微镜(AFM)等方法分析HRB400钢表面的钝化膜成分和微观形貌。结果 浸泡试验和电化学测试结果表明,钼酸钠对HRB400在含氯SCPS溶液中的腐蚀过程具有明显的抑制作用,随着钼酸钠浓度从0 mmol/L增加到6.4 mmol/L,缓蚀效果逐渐提升,当钼酸钠的浓度达到1.6 mmol/L时,缓蚀效率接近90%;SVET测试结果表明,钼酸钠能够促进HRB400钢表面钝化膜的生长,抵御Cl^(-)的侵蚀。XPS测试结果表明,钼酸钠能够吸附在HRB400钢表面,并且促使钝化膜中的Fe^(3+)/Fe^(2+)原子比从4.53变为7.11;AFM分析结果表明,HRB400钢在含氯SCPS溶液中钝化膜主要由纳米氧化物颗粒组成,加入钼酸钠后钝化膜上氧化物颗粒密度及尺寸增加,钝化膜的致密性增加。结论 钼酸钠在含氯SCPS溶液中能够延缓HRB400钢的腐蚀过程,钼酸钠的浓度为1.6 mmol/L时,缓蚀效率达到90%;钼酸钠属于阳极型缓蚀剂,其缓蚀作用主要是通过吸附在HRB400钢表面,促进钝化膜的形成及致密化。
The corrosion of steel reinforcement induced by chloride attack from deicing salts has long been a critical challenge compromising the safety,durability and service life of concrete infrastructure.This deterioration mechanism fundamentally originates from chloride ion penetration through concrete matrices,which disrupts the passive film on rebar surfaces and initiates the corrosion.The chloride resistance of steel reinforcement is intrinsically related to the stability of its surface passive film.To enhance passive film stability and inhibit chloride-induced corrosion,corrosion inhibitors are typically incorporated into deicing salt formulations.Sodium molybdate(Na_(2)MoO_(4)),as an inorganic inhibitor,has gained widespread application due to its cost-effectiveness,environmental friendliness and non-toxic characteristics.The work aims to systematically investigate the corrosion inhibition behavior of sodium molybdate on HRB400 steel in chloride-containing simulated concrete pore solutions.The experimental methodology incorporated immersion tests,electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization measurements to evaluate the inhibition efficiency of sodium molybdate and determine critical chloride concentrations for HRB400 steel in solutions with varying molybdate concentrations.Scanning vibrating electrode technique(SVET)was employed to in-situ monitor the corrosion activity evolution on steel surfaces.Post-immersion characterization techniques including X-ray photoelectron spectroscopy(XPS)and atomic force microscopy(AFM)were utilized to analyze the chemical composition and micromorphology evolution of passive films.Immersion tests and electrochemical measurements demonstrated that the sodium molybdate significantly inhibited the corrosion process of HRB400 steel in chloride-contaminated simulated concrete environments.The inhibition efficiency exhibited concentration-dependent enhancement,reaching 90%when the molybdate concentration attained 1.6 mmol/L.The adsorption behavior was calculated based on the electrochemical results,where the adsorption of the sodium molybdate on the iron substrate surface adhered to the Langmuir isothermal adsorption model,and the calculated adsorption equilibrium constant(Kads)for SM reached 5966.59,a significantly high value,indicating that SM exhibited outstanding corrosion inhibition efficacy.SVET monitoring revealed that the addition of molybdate effectively promoted passive film formation and improved chloride resistance,leading to substantial suppression of corrosion activity.XPS analysis indicated that molybdate ions adsorbed onto steel surfaces,inducing a notable increase in Fe^(3+)/Fe^(2+)atomic ratio within passive films from 4.53 to 7.114,which was about 70%enhancement.AFM characterization demonstrated that molybdate-modified passive films exhibited reduced surface roughness(Ra/Rp decreased from 4.27 nm/3.53 to 20.3 nm/16.3)and enhanced compactness compared to chloride-only systems,with the nanostructured oxide particles showing more homogeneous distribution.It is concluded that the sodium molybdate demonstrates effective corrosion inhibition for HRB400 steel in chloride-containing concrete environments through multiple mechanisms.As an anodic-type inhibitor,it preferentially adsorbs at active sites on steel surfaces,forming protective complexes that hinder chloride adsorption and charge transfer processes.Molybdate incorporation facilitates the transformation of less protective iron oxides(Fe_(2)O_(3)/Fe_(3)O_(4))into more stable FeOOH phases,enhancing passive film stability.The optimized inhibitor concentration of 1.6 mol/L achieves 90%efficiency by balancing competitive adsorption between MoO_(4)^(2-) and Cl^(-)ions.Microstructural densification of passive films through molybdate-induced crystallization refinement creates effective diffusion barriers against chloride penetration.These findings provide fundamental insights for developing molybdate-based corrosion mitigation strategies in chloride-exposed concrete structures.This comprehensive investigation establishes quantitative relationships between molybdate concentration,passive film characteristics,and corrosion resistance,offering practical guidance for optimizing inhibitor dosages in concrete durability applications.
作者
陈晓华
赵方超
周堃
史先飞
崔中雨
满成
吴德权
CHEN Xiaohua;ZHAO Fangchao;ZHOU Kun;SHI Xianfei;CUI Zhongyu;MAN Cheng;WU Dequan(School of Materials Science and Engineering,Ocean University of China,Shandong Qingdao 266100,China;Southwest Institute of Technology and Engineering,Chongqing 401329,China)
出处
《表面技术》
北大核心
2025年第12期37-48,共12页
Surface Technology
基金
国家重点研发计划青年科学家项目(2023YFB3710300)
国家自然科学基金(U2106216)
山东省高校“青年创新团队”计划(2022KJ055)
重庆市博士后基金(cstc2021jcyj-bshX0039)。
关键词
HRB400钢
模拟混凝土孔隙液
钝化膜
钼酸钠
临界氯离子浓度
电化学
HRB400 steel
simulated concrete pore fluid
passive film
sodium molybdate
critical chloride ion concentra-tion
electrochemical
