AZ91D镁合金表面双层硅烷膜的制备及其性能研究

采用γ-氨丙基三乙氧基硅烷（KH-550）和双-1，2-γ-三乙氧基硅丙基]-四硫化物（BTESPT）两种硅烷在AZ91D镁合金表面制备双层硅烷膜，通过正交试验选出了最佳制备工艺，即在KH-550硅烷中浸泡90 s，在BTESPT硅烷中浸泡5 min，再于80℃下固化90 min，得到550+BTESPT双层硅烷膜试样。通过接触角测试仪和动电位极化技术对试样进行润湿性和耐蚀性测试，通过扫描电子显微镜（SEM）、X射线能谱分析仪（EDS）对硅烷膜进行微观形貌和成分表征，通过X射线光电子能谱（XPS）对膜层元素的存在形式进行分析，结果表明：550+BTESPT双层硅烷膜表面接触角107.3°，表现为疏水性；在3.5%的NaCl溶液中，腐蚀电流密度为0.169 μA/cm²；硅烷膜表面形貌致密，主要有Mg、O、Si、S 4种元素组成；膜层中元素主要以Si-O-Si，Si-O-Mg，Si-O-X 3种形式存在。

Preparation and properties of a two-layer silane film on an AZ91D magnesium alloy surface

Two-layer silane films have been prepared on the surface of AZ91D magnesium alloy by using KH-550 and BTESPT. The best preparation process, selected on the basis of orthogonal tests, was found to involve immersion in KH-550 silane for 90 s, followed by immersion in BTESPT silane for 5 min, and curing at 80℃ for 90 min. The wettability and corrosion resistance of samples were tested by contact angle measurements and potentiodynamic polarization, the morphology and composition of the silane film were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), and the elemental composition was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the 550+BTESPT double-layer silane film was hydrophobic, with a surface contact angle of 107.3°; in 3.5% NaCl solution, the corrosion current density was 0.169 μA/cm²; the surface morphology is dense, and the silane film mainly consists of four elements:Mg, O, Si, and S; the elements in the film layer are mainly present in the forms Si-O-Si, Si-O-Mg, and Si-O-X.