5182铝合金表面硅烷涂层的制备与性能研究

Preparation and Properties of Silane Coating on 5182 Aluminum Alloy

目的提高5182铝合金表面耐蚀性能及其与漆膜的结合力。方法采用KH550硅烷试剂在5182铝合金表面制备硅烷涂层,同时探究不同浸泡时间、溶液pH值和固化温度对硅烷涂层结构和性能的影响,并优化硅烷涂层的制备工艺。采用扫描电子显微技术(SEM)、接触角试验仪和拉曼光谱研究硅烷涂层的结构和成分。采用电化学阻抗谱(EIS)技术评价涂层的耐蚀性能。采用涂层附着力自动划痕仪评价硅烷涂层对有机漆膜结合力的影响。结果浸泡时间180 s、溶液pH值11、固化温度90℃为5182铝合金表面硅烷涂层的最佳制备工艺,该工艺条件下制备的硅烷涂层均匀、致密地覆盖于铝合金基体表面,厚度约为100 nm。在Na_2B_4O_7×10H_2O和NaOH水溶液中,硅烷处理试样的低频阻抗值比未硅烷处理试样高约2个数量级,硅烷处理样品与漆膜的结合力明显优于未经过硅烷处理的试样。结论采用优化工艺制备的硅烷涂层能改善5182铝合金的耐蚀性能。当硅烷涂层作为中间层存在时,显著提高了有机涂层与合金基体的结合强度。

The work aims to improve the corrosion resistance and adhesion strength with coating on 5182 aluminum alloy. Silane coating was prepared on 5182 aluminum alloy with silane agent KH550. Effects of different immersion time, p H and curing temperature on structure and properties of the silane coating were investigated, and then the preparation process of silane coating was optimized. The structure and composition of the silane coating were studied by scanning electron microscopy（SEM）, contact angle tester and Raman spectrum. Electrochemical impedance spectroscopy（EIS）was used to evaluate the corrosion performance of the coating. The automatic scratch tester for coating adhesion was applied to evaluate the influence of silane coating on the adhesion strength of organic coating. The optimum preparation process of silane coating on 5182 aluminum alloy was immersion time of 180 s, p H of 11 and curing temperature of 90 ℃. The silane coating prepared under such process condition was evenly and densely placed on aluminum alloy substrate and about 100 mm thick. In the Na2 B4 O7·10 H2 O and Na OH solution, the low frequency impedance of silane treated sample was about 2 orders of magnitude higher than that of un-treated sample. The adhesion property of the silane treated sample to organic coating was also much better than the un-treated sample. The silane coating prepared by optimized process can improve the corrosion resistance of 5182 aluminum alloy as well as the adhesion strength of organic coating to the alloy substrate when used as intermediate layer.