Calderón Jesús Porcayo, Reyes Barragán José Luis, Barraza Fierro Jesús Israel, Cruz Mejía Héctor, Arrieta González Cinthya Dinorah, Ravelero Vázquez Víctor, Sánchez Kevin Piedad, Torres-Mancera María Teresa, Retes-Mantilla Rogel Fernando, Rodríguez-Díaz Roberto Ademar
Departamento de Ingeniería Química y Metalurgia, Universidad de Sonora, Hermosillo 83000, Mexico.
Departamento de Ingeniería en Diseño, Universidad Politécnica de la Zona Metropolitana de Guadalajara, Tlajomulco de Zúñiga 45640, Mexico.
Materials (Basel). 2022 Jun 15;15(12):4229. doi: 10.3390/ma15124229.
Aluminum-based alloys have been considered candidate materials for cathodic protection anodes. However, the Al-based alloys can form a layer of alumina, which is a drawback in a sacrificial anode. The anodes must exhibit uniform corrosion to achieve better performance. Aluminum can be alloyed with Zn to improve their performance. In this sense, in the present research, the electrochemical corrosion performance of Al-xZn alloys (x = 1.5, 3.5, and 5 at.% Zn) exposed to 3.5 wt.% NaCl for 24 h was evaluated. Polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to identify the electrochemical behavior. The microstructure of the samples before the corrosion assessment was characterized by means of X-ray diffraction analyses (XRD) and scanning electron microscopy (SEM). In addition, microstructures of the corroded surfaces were characterized using X-ray mappings via SEM. Polarization curves indicated that Zn additions changed the pseudo-passivation behavior from what pure Al exhibited in a uniform dissolution regime. Furthermore, the addition of Zn shifted the corrosion potential to the active side and increased the corrosion rate. This behavior was consistent with the proportional decrease in polarization resistance (R) and charge transfer resistance () in the EIS. The analysis of EIS was done using a mathematical model related to an adsorption electrochemical mechanism. The adsorption of chloride at the Al-Zn alloy surface formed aluminum chloride intermediates, which controlled the rate of the process. The rate constants of the reactions of a proposed chemical mechanism were evaluated.
铝基合金一直被视为阴极保护阳极的候选材料。然而，铝基合金会形成一层氧化铝，这在牺牲阳极中是一个缺点。阳极必须表现出均匀腐蚀才能获得更好的性能。铝可以与锌合金化以改善其性能。从这个意义上说，在本研究中，评估了Al-xZn合金（x = 1.5、3.5和5原子百分比的锌）在3.5重量百分比的氯化钠中暴露24小时后的电化学腐蚀性能。使用极化曲线、线性极化电阻（LPR）和电化学阻抗谱（EIS）来确定电化学行为。在进行腐蚀评估之前，通过X射线衍射分析（XRD）和扫描电子显微镜（SEM）对样品的微观结构进行了表征。此外，通过扫描电子显微镜使用X射线映射对腐蚀表面的微观结构进行了表征。极化曲线表明，添加锌改变了纯铝在均匀溶解状态下所表现出的伪钝化行为。此外，锌的添加使腐蚀电位向活性侧移动并提高了腐蚀速率。这种行为与EIS中极化电阻（R）和电荷转移电阻（）的成比例降低一致。使用与吸附电化学机制相关的数学模型对EIS进行了分析。氯离子在铝锌合金表面的吸附形成了氯化铝中间体，它控制了该过程的速率。对所提出的化学机制反应的速率常数进行了评估。
