6061铝合金表面硅烷自组装膜的制备及性能研究

发布时间：2018-03-09 01:36

本文选题：铝合金　切入点：自组装膜　出处：《北京科技大学》2017年博士论文　论文类型：学位论文

【摘要】：铝合金是最常用的金属结构材料之一,在冰箱、冰柜制冷蒸发器中铝材已逐步替代铜管材料。但铝材易发生局部腐蚀,造成制冷设备发生故障。因此,开发工艺简单、耐腐蚀性能优异的表面防护膜层显得很有必要。为此,针对冰箱、冰柜蒸发器用铝材的特点和要求,本论文选用工艺简单的自组装技术用与铝材的表面处理上,系统探讨了三个关键科学问题：(1)、优化自组装膜的制备工艺参数：(2)、研究自组装膜结构及其耐蚀性能的变化规律；(3)、结合分子动力学模拟方法,研究自组装膜在铝合金表面的自组装行为,揭示自组装膜特定原子与金属表面之间的化学键成膜机制。本文首先运用自组装技术在铝合金表面制备了以双(Y-三乙氧基硅基丙基)四硫化物(BTESPT)和十二氟庚基丙基三甲氧基硅烷(G502)为主成膜剂的自组装膜,考察了自组装液浓度、自组装时问、固化温度和固化时间对自组装膜的影响规律,获得了制备自组装膜的优化工艺参数。在单一自组装膜基础上,尝试采用掺杂和复合方法制备了自组装复合膜。其次采用SEM、面扫描、XPS、中性盐雾腐蚀试验和腐蚀电化学性能测试等多种方法,分别研究了G502和BTESPT自组装膜的形貌、组成、结构和耐腐蚀性能。结果表明：两种自组装膜层能呈现良好覆盖性和平整度的网格状结构：自组装分子元素在膜层表面分布均匀；BTESPT依靠O、S和H原子与金属形成AI-O-Si、R-S-OR和Al-O-OH化学键,而G502仅依靠O形成Al-O-Si化学键；BTESPT自组装膜的耐中性盐雾腐蚀时长比G502自组装膜的高出3倍多,耐蚀性能提高了约15%,且BTESPT自组装膜经120小时中性盐雾腐蚀试验仍保持完好,超过了现有技术标准要求；腐蚀电化学性能测试显示自组装膜电化学行为是以控制电化学阳极极化为主。对自组装复合膜耐蚀性能研究表明复合膜耐蚀性能提高不是很明显。最后,运用分子动力学模拟方法分别研究了G502和BTESPT自组装分子在Al(110)面的吸附机理。结果表明：G502和BTESPT自组装膜分别依靠各自分子中的特征原子与A1原子间形成化学键,BTESPT依靠O、S和H原子与金属形成Al-O-Si、R-S-OR和Al-O-OH化学键,而G502仅依靠O形成Al-O-Si化学键,推断BTESPT在金属表面能形成具有比G502覆盖度更高、致密性更好的分子吸附膜,有效阻挡腐蚀介质与金属表面直接接触,达到提高铝合金表面耐腐蚀性能的目的。总的来说,以BTESTP为主成膜剂的自组装膜耐蚀性能要优于以G502主成膜剂的耐蚀性能,更适用于冰箱、冰柜制冷蒸发器中铝材的表1面处理,从而延长蒸发器的使用寿命。
[Abstract]:Aluminum alloy is one of the most commonly used metal structural materials. Aluminum has gradually replaced copper pipe material in refrigerators and freezer refrigerators. However, aluminum materials are prone to local corrosion, resulting in the failure of refrigeration equipment. Therefore, the development process is simple. The surface protective coating with excellent corrosion resistance is very necessary. In view of the characteristics and requirements of aluminum for refrigerators and freezer evaporators, this paper uses simple self-assembly technology and aluminum surface treatment. In this paper, three key scientific problems are discussed systematically. The preparation process parameters of the self-assembled films are optimized, the structure and corrosion resistance of the self-assembled films are studied, and the molecular dynamics simulation method is used to study the structure and corrosion resistance of the self-assembled films. Self-assembly behavior of self-assembled films on aluminum alloy surface was studied. The mechanism of chemical bonding film formation between specific atoms and metal surface of the self-assembled film was revealed. In this paper, BTESPT and 12 fluoroheptyl propyl tetrasulphide (BTESPT) and 12 fluoroheptyl propyl were prepared on aluminum alloy surface by self-assembly technique. Self-assembled films of trimethoxysilane (G502) as the main film forming agent, The effects of the concentration of the self-assembled liquid, the self-assembly time, the curing temperature and the curing time on the self-assembly film were investigated, and the optimized process parameters were obtained. The self-assembled composite films were prepared by doping and recombination methods. Secondly, the morphology and composition of G502 and BTESPT self-assembled films were studied by means of SEM, surface scan XPSs, neutral salt spray corrosion test and electrochemical corrosion performance test, respectively. Structure and corrosion resistance. The results show that two kinds of self-assembled films can exhibit good coverage and smoothness of mesh structure: the self-assembled molecular elements are uniformly distributed on the surface of the films. BTESPT forms AI-O-SiR-S-OR and Al-O-OH chemical bonds with metals by OCS and H atoms. On the other hand, the corrosion resistance of G502 self-assembled film is more than three times longer than that of G502 self-assembled film, and the corrosion resistance of BTESPT self-assembled film is improved by about 15%, and the BTESPT self-assembled film remains intact after 120 hours neutral salt spray corrosion test. Exceeding the requirements of existing technical standards; The corrosion electrochemical performance test shows that the electrochemical behavior of the self-assembled film is mainly controlled by electrochemical anodic polarization. The corrosion resistance of the self-assembled composite film is not obviously improved. The adsorption mechanism of G502 and BTESPT self-assembled molecules on Al _ (110) surface was studied by molecular dynamics simulation method. The results show that the self-assembled films of BTESPT and G502 depend on the formation of chemical bonds between the characteristic atoms and A1 atoms in their respective molecules. The Al-O-Si-R-S-OR and Al-O-OH chemical bonds are formed by the atoms of O _ (S) and H with metals. However, G502 only depends on O to form Al-O-Si chemical bond. It is inferred that BTESPT can form a molecular adsorption film on metal surface with higher covering degree and better density than G502, which can effectively block the direct contact between corrosion medium and metal surface. In general, the corrosion resistance of the self-assembled film with BTESTP as the main film is better than that of the G502 main film, and it is more suitable for refrigerators. The surface treatment of aluminum in freezer refrigeration evaporator can prolong the service life of evaporator.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG174.4

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