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采用极化曲线、电化学阻抗、电化学噪声以及形貌观测研究了AA6061铝合金在3.5%(质量分数)NaCl薄液膜下的点蚀诱发以及缓蚀剂抑制过程。结果表明:在Na Cl薄液膜下,Ce~(3+)作为阴极性缓蚀剂往往在铝合金表面的第二相组织(如Mg2Si等微阴极相)碱化区发生优先沉积,使铝合金局部腐蚀受到抑制;薄液膜越薄,Ce~(3+)在微阴极区形成的沉积层越致密,进而显著抑制铝合金微阴极相表面的氧还原过程以及亚稳态点蚀的萌生和稳态点蚀发展。相反,在含相同浓度Ce~(3+)的Na Cl溶液中,由于Ce~(3+)的氧化过程受到溶液中氧扩散速率的限制,导致Ce~(3+)在溶液中对亚稳态点蚀的抑制能力相比薄液膜有所下降,即薄液膜下Ce~(3+)的局部腐蚀抑制能力强于本体溶液中的。
Pitting corrosion and inhibitor inhibition of AA6061 aluminum alloy under 3.5% (mass fraction) NaCl thin film were investigated by polarization curve, electrochemical impedance, electrochemical noise and morphology observation. The results show that under NaCl thin film, Ce 3+ as a cathode inhibitor tends to deposit preferentially in the alkalinization zone of the second phase of the aluminum alloy (such as Mg2Si) The local corrosion of the alloy is inhibited. The thinner the thin film is, the denser the deposition layer of Ce 3+ in the micro-cathode region, and then the oxygen reduction process and the metastable pitting initiation of the micro-cathode phase of the aluminum alloy are significantly inhibited And steady-state pitting development. On the contrary, the Ce (3+) solution in CeCl 3 solution is stable due to the oxidation of Ce 3+ by the diffusion rate of oxygen in the solution. Compared with the thin film, the inhibition of pitting corrosion is lower than that of the thin film, that is, the local corrosion inhibition ability of Ce 3+ in the thin film is stronger than that in bulk solution.