Zeng Zeyun, Gu Shangjun, Wang Jie, Wei Fulong, Xie Xiang, Li Zhiying, Yang Hui, Li Changrong
College of Materials and Metallurgy, Guizhou University, Guiyang, 550025, China.
Guizhou Provincial Key Laboratory of Metallurgical Engineering and Process Energy Saving, Guiyang, 550025, China.
Sci Rep. 2024 Oct 2;14(1):22919. doi: 10.1038/s41598-024-74763-0.
In this study, XPS sputtering depth, SEM and electrochemical tests (CV, EIS, M-S, i-t, DPP) were used to study the structural composition and formation mechanism of surface passive film of Nb microalloyed rebar in SCPS with different pH. The results showed that after passivation for 10 d in SCPS with different pH, compared with CS rebar, the stability and compactness of surface passive film of 34Nb rebar gradually increased with the decreases of pH. Firstly, with the decreases of pH, the outer layer of surface passive film of 34Nb rebar was composed of Fe oxides and Fe hydroxides, and the inner layer was composed of Fe oxides and Nb oxides, thus increasing the mass ratio of Fe/Fe and NbO/(NbO + NbO). Secondly, with the decreases of pH, the addition of Nb promoted the formation of Fe oxides in 34Nb rebar, obtaining the excellent R, E and E. Finally, with the decreases of pH, the addition of Nb promoted the enrichment of Nb oxides in 34Nb rebar, inhibiting the degradation of Fe oxides, and the passive film exhibited the P-N type semiconductor, thus significantly decreasing the carrier density and enhancing the passivation rate of 34Nb rebar.
在本研究中，采用X射线光电子能谱溅射深度分析、扫描电子显微镜以及电化学测试（循环伏安法、电化学阻抗谱、动电位极化曲线、电流-时间曲线、差示脉冲伏安法）来研究不同pH值的模拟混凝土孔溶液（SCPS）中铌微合金化钢筋表面钝化膜的结构组成和形成机制。结果表明，在不同pH值的SCPS中钝化10天后，与碳钢钢筋相比，34Nb钢筋表面钝化膜的稳定性和致密性随pH值降低而逐渐增加。首先，随着pH值降低，34Nb钢筋表面钝化膜外层由铁的氧化物和氢氧化物组成，内层由铁的氧化物和铌的氧化物组成，从而提高了Fe/Fe以及NbO/(NbO + NbO)的质量比。其次，随着pH值降低，铌的添加促进了34Nb钢筋中铁氧化物的形成，使其具有优异的极化电阻、点蚀电位和缝隙腐蚀电位。最后，随着pH值降低，铌的添加促进了34Nb钢筋中铌氧化物的富集，抑制了铁氧化物的降解，钝化膜呈现P-N型半导体特性，从而显著降低载流子密度并提高34Nb钢筋的钝化率。
