Inhibition effect of cationic surfactant of tetradecylpyridinium bromide (TDPB) on the corrosion of cold rolled steel (CRS) in phosphoric acid produced by dihydrate wet method process (7.0 M H3PO4) was investigated by weight loss and potentiodynamic polarization methods and electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Quantum chemical calculation was applied to elucidate the adsorption mode of the inhibitor molecule on steel surface. The results show that TDPB acts as a good inhibitor, and its maximum inhibition efficiency is higher than 90% even at low concentration. The adsorption of TDPB obeys the Langmuir adsorption isotherm equation. Polarization curves indicate that TDPB behaves as a mixed-type inhibitor in H3PO4. EIS spectra exhibit one capacitive loop which indicates that the corrosion reac- tion is controlled by charge transfer process. The inhibition action of TDPB could also be evidenced by surface SEM images. Density functional theory (DFT) calculations suggest that the pyridine ring is the active adsorption center. Depending on the results, the inhibitive mechanism is proposed from the viewpoint of adsorption theory.

中文翻译：

---

十四烷基溴化吡啶对冷轧钢在 7.0 MH 3 PO 4 中的腐蚀抑制作用

通过失重法、动电位极化法和电化学阻抗谱(EIS)研究了溴化十四烷基吡啶鎓阳离子表面活性剂(TDPB)对冷轧钢(CRS)在二水湿法工艺磷酸(7.0 M H3PO4)中腐蚀的抑制作用。 ) 和扫描电子显微镜 (SEM)。应用量子化学计算阐明了缓蚀剂分子在钢表面的吸附方式。结果表明，TDPB是一种良好的抑制剂，即使在低浓度下其最大抑制效率也高于90%。TDPB的吸附服从Langmuir吸附等温方程。极化曲线表明 TDPB 在 H3PO4 中表现为混合型抑制剂。EIS 谱显示出一个电容回路，表明腐蚀反应受电荷转移过程控制。TDPB 的抑制作用也可以通过表面 SEM 图像来证明。密度泛函理论 (DFT) 计算表明，吡啶环是活性吸附中心。根据结果​​，从吸附理论的角度提出了抑制机制。