铝合金刷镀银前处理工艺对镀层性能的影响

发布时间：2018-05-28 15:25

  本文选题：铝合金 + 刷镀银　； 参考：《沈阳工业大学》2017年硕士论文

【摘要】：铝及铝合金具有比重小、压铸加工便利、导电性与导热性好等优点,在工业生产中应用日益广泛。随着科技的进步,和人们生活水平的不断提高,对铝合金的需求日益增加,不论是航天航空领域的轻型材料,还是汽车轻量化技术都离不开铝合金的参与。但是铝及铝合金也存在易产生晶间腐蚀,表面硬度低,不耐磨等性质。对铝进行电镀,改善其表面性能是十分有必要的。铝合金镀银是对其表面改性的重要的一种方法,对于一些特殊铝合金工件往往采用电刷镀的办法。铝表面容易在空气中与氧气反应生成一种自然氧化膜,导致被镀金属与基体结合力不好,目前针对铝合金镀银已经有很多前处理办法能够得到合适的刷镀银层。但随着铝合金应用环境更广泛,在一些高温环境下铝合金刷镀银层与基体结合力不佳。解决铝合金刷镀银层能够耐500℃高温热震是本课题的目的。实验过程中研究了浸锌前处理以及阳极氧化前处理工艺对氰化物体系刷镀银层的影响,研究不同前处理工艺或工艺参数对其微观形貌、耐蚀性、耐热震性、抗变色性的影响。选取阳极氧化时间为4min氧化电压为13V的工艺参数处理铝合金表面、并对使用有氰预镀银-无氰刷镀银与无氰预镀银-无氰刷镀银所得镀层的综合性能进行比较。研究结果发现通过四种浸锌工艺得到的刷镀银层不耐500℃热震,前处理过程中浸锌与预镀铜会夹杂在镀层与铝合金基体之间,在高温下通过镀层缝隙扩散到达镀层表面。在氧化时间为4min氧化电压为13V及氧化时间为10min氧化电压为13V时能够得到耐热震500℃的刷镀银层;结合生产实际,减小时间成本,选用氧化时间4min、氧化电压13V作为阳极氧化参前处理参数,在此参数基础上的有氰体系刷镀银层在0.1mmol/L Na2S与0.1mol/L K2SO4溶液中自腐蚀电流密度分别为1.898×10-6A/cm2,9.43×10-6 A/cm2;在氧化时间为4min氧化电压为13V的前处理参数下,无论采用有氰预镀还是无氰预镀方法,有氰预镀-无氰刷镀银层耐蚀性要比无氰预镀-无氰刷镀银层耐蚀性要好,两种刷镀银层耐热震性能均不佳。
[Abstract]:Aluminum and aluminum alloys are widely used in industrial production because of their advantages such as low specific gravity, convenient die casting, good conductivity and good thermal conductivity. With the development of science and technology and the improvement of people's living standard, the demand for aluminum alloy is increasing day by day. Both the light materials in aerospace field and the lightweight technology of automobile can not be separated from the participation of aluminum alloy. However, aluminum and aluminum alloys are also prone to intergranular corrosion, surface hardness, wear resistance and other properties. It is necessary to electroplate aluminum to improve its surface properties. Silver plating is an important method for surface modification of aluminum alloy, and brush plating is often used for some special aluminum alloy workpieces. The surface of aluminum can easily react with oxygen in air to form a kind of natural oxide film, which leads to poor adhesion between metal and substrate. At present, there are many pre-treatment methods for silver plating of aluminum alloy to obtain suitable brushing silver coating. However, with the wide application of aluminum alloy, the adhesion between silver coating and substrate is not good in some high temperature environments. The purpose of this project is to solve the problem that the silver coating of aluminum alloy brushes can withstand 500 鈩，

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