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紫铜表面MPTES薄膜的制备及耐腐蚀性能
【作者】 路学斌；
【导师】 陈明安；
【作者基本信息】 中南大学 ， 材料加工工程， 2011， 硕士
【摘要】 为提高紫铜的耐腐蚀性能,采用3-巯丙基三乙氧基硅烷(MPTES)对紫铜进行表面硅烷化处理。分别采用不同的硅烷溶液pH值和不同的水解时间在紫铜表面制备MPTES薄膜。利用傅里叶变换红外光谱(FTIR)分析了不同条件下硅烷的水解状态及其对所得MPTES薄膜结构的影响；综合利用极化曲线、电化学阻抗谱(EIS)、循环伏安曲线和盐水浸泡实验分析测试了不同制备工艺对MPTES薄膜耐腐蚀性能的影响规律；利用扫描电镜(SEM)及FTIR分析了MPTES薄膜在3.5%(w) NaCl溶液中浸泡后形貌及结构特征的变化。实验结果表明：酸性硅烷溶液中MPTES的水解程度高于碱性溶液,所得的薄膜中硅烷分子以Si-O-Si键相互交联的程度较高。由酸性硅烷溶液制备的MPTES薄膜的耐腐蚀性能优于碱性硅烷溶液中制备的薄膜。在酸性溶液中MPTES需要至少24h才能达到较好的水解状态。水解时间为2h的MPTES薄膜中存在较多缺陷；而水解时间较长的薄膜中产生了较多长链的Si-O-Si结构且缺陷较少。与光板相比,水解时间为2h的薄膜使紫铜的腐蚀电流密度降低了1-2个数量级,而水解时间较长的薄膜使其降低了3个数量级。在循环伏安测试和电化学阻抗谱测试过程中水解时间为48 h的MPTES薄膜表现出最佳的耐腐蚀性能。水解2h的MPTES薄膜覆盖紫铜样品在3.5%(w) NaCl溶液中浸泡1周后表面即出现点蚀,4周后出现大片腐蚀区域。水解48 h的样品在浸泡1周时无明显腐蚀迹象,4周后出现点蚀。浸泡后的MPTES薄膜中Si-O-Si键发生了断裂。
【Abstract】 Films of (3-mercaptopropyl)triethoxysilane (MPTES) with different solution pH value or different hydrolysis time were formed on copper surface. Fourier transform infrared spectroscopy (FTIR) was used for structural characterization of MPTES films. Polarization curves, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry measurements were used for evaluating the corrosion protective performance of MPTES films. Scanning electron microscope (SEM) and FTIR analysis were used for characterization of surface morphology and structures of the films after immersion in 3.5%(w) NaCl solution. The results are as follows:The hydrolysis degree of MPTES in acid silane solution is higher than that in basic silane solution. The film obtained in acid silane solution contains more Si-O-Si bonds and shows better corrosion protective performance.At least 24 hours are required to obtain a well hydrolyzed silane solution in acid condition. The MPTES film obtained in the 2 h hydrolyzed solution contains a number of defects, while the films obtained in long time hydrolyzed solutions are dominated with long chain Si-O-Si units and contain fewer defects. Compared with the bare copper, the corrosion current density of the specimen covered with 2 h hydrolyzed film is reduced by 1-2 orders of magnitude, while the films with longer hydrolysis time cause a decrease by about 3 orders of magnitude. The MPTES film obtained in 48 h hydrolyzed solution shows the best corrosion protective performance in cyclic voltammetry and EIS measurements.After 1 week of immersion in NaCl solution, pitting occurs on the surface of copper covered by 2 h hydrolyzed MPTES film; after 4 weeks the corrosion become more severe. For 48 h hydrolyzed sample no corrosion can be observed after 1 week but pitting occurs after 4 weeks. The Si-O-Si bonds in MPTES films are partly broken after immersion.