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利用动电位极化曲线、交流阻抗技术及Mott-Schottky曲线等方法,研究了钼酸钠对钢筋在5%NaCl混凝土模拟液中的电化学腐蚀行为和表面钝化膜性能的影响.结果表明:随钼酸钠浓度增大,缓蚀效率逐渐增加,对钢筋的腐蚀有较好地抑制作用,药剂在钢筋表面的吸附可有效屏蔽氯离子的侵蚀作用;Mott-Schottky结果表明,在-0.5~0.1 VSCE范围内,混凝土模拟液中钢筋表面钝化膜Cs-c2-E曲线呈正线性相关,表明钢筋表面钝化膜为n型半导体,且随钼酸钠浓度增大,钢筋钝化膜载流子密度逐渐减小,钝化膜稳定性增强,耐蚀性逐步提高;钝化膜致密性分析表明,随钼酸钠浓度增大,钝化膜致密性增加,抗氯离子腐蚀能力增强.
The effects of sodium molybdate on electrochemical corrosion behavior and surface passivation film properties of steel bars in 5% NaCl concrete simulation liquid were studied by potentiodynamic polarization curves, AC impedance techniques and Mott-Schottky curves.The results showed that: As the concentration of sodium molybdate increases, the corrosion inhibition efficiency increases gradually, which inhibits the corrosion of steel bars. The adsorption of chemical agents on the steel surface can effectively shield the corrosion of chloride ions. Mott-Schottky’s results show that at -0.5 ~ In the range of 0.1 VSCE, the Cs-c2-E curve of the passivation film on the steel surface in the concrete simulations shows a positive linear correlation, indicating that the passive film on the surface of the steel bar is an n-type semiconductor. With the increase of sodium molybdate concentration, The density of passivation film is gradually decreased, the stability of passivation film is enhanced and the corrosion resistance is gradually increased. The analysis of passivation film density shows that as the concentration of sodium molybdate increases, the densification of passivation film increases and the resistance to chloride ion corrosion increases.