Enhanced corrosion efficiency of low-carbon steel was achieved by newly developed hybrid multilayers, composed of low-carbon steel coated with an electrodeposited zinc sublayer (1 µm), a chitosan (CS) middle layer and ZrO₂ coating by the sol–gel method (top-layer). The middle chitosan layer was obtained by dipping galvanized steel substrate in 3% tartatic acid water solution of medium molecular-weight chitosan, composed of β-(1–4)-linked D-glucosamine and N-acetyl-D-glucosamine with a deacetylation degree of about 75–85% (CS). The substrates were dipped into CS solution and withdrawn at a rate of 30 mm/min. One part of the samples with the CS layer was dried at room temperature for 2 weeks, and another part at 100 °C for 1 h, respectively. After CS deposition treatment, the substrates were dipped into an isopropanol sol of zirconium butoxide with small quantity of polyethylene glycol (PEG400). The dipping-drying cycles of the ZrO₂ coatings were repeated three times. After the third cycle, the final structures were treated at 180 °C. The samples were denoted as T25, which consists of the CS middle layer, and dried at RT and T100 with the CS middle layer treated at 100 °C, respectively. The samples were characterized by means of differential thermal analysis (DTA-TG), XRD analyses, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Hydrophobicity properties were evaluated by measuring the contact angle with a ramé-hart automated goniometer. Two electrochemical tests—potentiodynamic polarization technique (PD) and electrochemical impedance spectroscopy (EIS)—have been used to determine the corrosion resistance and protective ability of the coatings in a 5% NaCl solution. The results obtained by both methods revealed that the applied “sandwich” multilayer systems demonstrate sacrificial character and will hopefully protect the steel substrate in corrosion medium containing chloride ions as corrosion activators. The newly obtained hybrid multilayer coating systems have dense structure and a hydrophobic nature. They demonstrated positive effects on the corrosion behavior at conditions of external polarization independent of their various characteristics: morphology, grain sizes, surface roughness and contact angle. They extend the service life of galvanized steel in a chloride-containing corrosion medium due to their amorphous structure, hydrophobic surface and the combination of the positive features of both the chitosan middle layer and the zirconia top layer.

中文翻译：

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ZrO2/壳聚糖“三明治”涂层在镀锌低碳钢上的保护效率

通过新开发的混合多层膜提高低碳钢的腐蚀效率，该多层膜由涂有电沉积锌亚层 (1 µm) 的低碳钢、壳聚糖 (CS) 中间层和通过溶胶-凝胶法制成的ZrO ₂涂层组成（顶层）。中间壳聚糖层是通过将镀锌钢基材浸入 3% 的中分子量壳聚糖的酒石酸水溶液中获得的，由 β-(1-4)-连接的 D-氨基葡萄糖和N 组成。-乙酰-D-氨基葡萄糖，脱乙酰度约为 75-85% (CS)。将基板浸入 CS 溶液中并以 30 毫米/分钟的速度取出。一部分带有 CS 层的样品在室温下干燥 2 周，另一部分在 100°C 下干燥 1 小时。CS沉积处理后，将基板浸入丁醇锆的异丙醇溶胶和少量聚乙二醇（PEG400）中。ZrO ₂的浸渍-干燥循环涂层重复 3 次。第三次循环后，最终结构在 180 °C 下进行处理。样品表示为 T25，由 CS 中间层组成，并在 RT 和 T100 下干燥，CS 中间层分别在 100°C 处理。通过差热分析 (DTA-TG)、XRD 分析、X 射线光电子能谱 (XPS) 和原子力显微镜 (AFM) 对样品进行表征。通过用 ramé-hart 自动测角仪测量接触角来评估疏水性。两种电化学测试——动电位极化技术 (PD) 和电化学阻抗谱 (EIS)——已被用于确定涂层在 5% NaCl 溶液中的耐腐蚀性和保护能力。通过两种方法获得的结果表明，所应用的“夹心”多层系统表现出牺牲特性，有望在含有氯离子作为腐蚀活化剂的腐蚀介质中保护钢基材。新获得的混合多层涂层系统具有致密的结构和疏水性。它们在外部极化条件下表现出对腐蚀行为的积极影响，而与其各种特征无关：形态、晶粒尺寸、表面粗糙度和接触角。由于它们的无定形结构、疏水表面以及壳聚糖中间层和氧化锆顶层的积极特征的结合，它们延长了镀锌钢在含氯化物腐蚀介质中的使用寿命。