Lei Donghao, Wang Ziyi, Qiao Jinjun, An Lingyun, Chang Chenggong, Meng Leichao, Wang Zhanying, Yang Yanping
Qinghai Provincial Key Laboratory of Nanomaterials and Technology, School of Chemistry and Materials Science, Qinghai Minzu University, Xining 810007, China.
Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lake, Chinese Academy of Sciences, Xining 810008, China.
Materials (Basel). 2025 Sep 4;18(17):4146. doi: 10.3390/ma18174146.
To explore the influence of the microstructure of plasma electrolytic oxidation (PEO) coating on the loading of corrosion inhibitors and the silanization treatment on its surface, PEO coatings were first prepared on the surface of AZ31B magnesium alloy under different voltages. Secondly, sodium tungstate (NaWO) was loaded into the micropores and onto the surface of the PEO coatings via vacuum impregnation, and which were subsequently subjected to silanization treatment. The phase composition of the coatings was studied by XRD, while the elemental composition and valence state were investigated by XPS. The surface and cross-sectional morphology of the coatings, as well as the composition and distribution of elements, were studied by SEM and EDS. Image J software was employed to analyze the thickness of the coatings. The results show that the microstructure of PEO coatings prepared under different voltages varies, which affects the loading of NaWO on the surface of PEO coating and the sealing effect of silanization treatment, thereby influencing the corrosion resistance of the coatings. As the voltage increases, the coating thickness and roughness gradually increase, while the surface porosity first increases and then decreases, and the loaded content of NaWO also follows a trend of first increasing and then decreasing. Meanwhile, at 300 V and 350 V, silanization treatment effectively seals the PEO coatings loaded with NaWO. However, when the voltage increases to 400 V, due to the uneven surface of the PEO coating, nonuniform distribution of micropores, and high roughness, the silanization treatment fails to completely cover the coating. This results in defects such as pits on the surface of the composite coating prepared at 400 V. Therefore, the composite coating prepared at 350 V exhibits the best corrosion resistance. After immersion in a 3.5 wt.% NaCl solution for 240 h, the composite coating formed at 350 V remains intact, and its low-frequency impedance modulus |Z| is as high as 1.06 × 10 cm. This value is approximately two orders of magnitude higher than that of the composite coating fabricated at 400 V and about three orders of magnitude higher than that of the pure PEO coating prepared at 350 V.
为探究微弧氧化（PEO）涂层微观结构对缓蚀剂负载量的影响以及其表面的硅烷化处理，首先在不同电压下于AZ31B镁合金表面制备PEO涂层。其次，通过真空浸渍将钨酸钠（NaWO）载入PEO涂层的微孔及表面，随后对其进行硅烷化处理。采用XRD研究涂层的相组成，利用XPS研究元素组成和价态。通过SEM和EDS研究涂层的表面及截面形貌以及元素的组成和分布。使用Image J软件分析涂层厚度。结果表明，不同电压下制备的PEO涂层微观结构不同，这影响了NaWO在PEO涂层表面的负载量以及硅烷化处理的封孔效果，进而影响涂层的耐蚀性。随着电压升高，涂层厚度和粗糙度逐渐增大，而表面孔隙率先增大后减小，NaWO的负载量也呈先增大后减小的趋势。同时，在300 V和350 V时，硅烷化处理有效地封孔了负载NaWO的PEO涂层。然而，当电压升高到400 V时，由于PEO涂层表面不平、微孔分布不均且粗糙度高，硅烷化处理未能完全覆盖涂层。这导致在400 V制备的复合涂层表面出现 pits等缺陷。因此，350 V制备的复合涂层表现出最佳的耐蚀性。在3.5 wt.% NaCl溶液中浸泡240 h后，350 V形成的复合涂层保持完整，其低频阻抗模量|Z|高达1.06×10 cm。该值比400 V制备的复合涂层高出约两个数量级，比350 V制备的纯PEO涂层高出约三个数量级。
