【作者】 王巍；

【导师】 徐文骥；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 电镀铬是工业上应用最广泛的电镀技术之一,其产品遍及日常生活与工业生产等诸多领域。传统的镀铬是采用六价铬镀铬工艺进行的。由于六价铬电镀铬工艺存在电流效率低、能耗大、覆盖能力差等缺点,特别是六价铬具有对操作工人身体危害极大与污染环境严重的问题,使得采用新型镀铬技术来取代六价铬电镀成为必然趋势。本论文采用甲酸铵与草酸铵复合作为配位剂的氯化物体系电镀液进行三价铬电镀。该体系基本上克服了上述六价铬电镀的缺点,具有低毒环保、不受电流中断的影响和可在常温下电镀等优点。采用该体系镀液在金属表面进行电镀,可得到外观光亮,结合力与耐蚀性较好的镀铬层,基本满足装饰性镀铬的需求,具有一定的实用价值。本文的主要工作包括以下三个部分：(1)金属表面三价铬电镀采用甲酸铵与草酸铵复合配位剂体系三价铬电镀液,在铜和45钢两种金属材料表面进行三价铬电镀。利用正交试验法进行小槽实验,以镀铬层的厚度作为考核指标,优化选择电镀液中两种配位剂的浓度,阴极电流密度与电镀时间等工艺参数,结合镀液pH值与温度对镀层外观的影响,获得良好的电镀工艺条件。采用优化后的工艺条件,可在金属表面获得外观光亮、分布均匀致密,纯度较高,结合力与耐蚀性较好的镀铬层。(2)非金属表面化学镀铜采用甲醛-酒石酸钾钠镀铜体系镀液,在尼龙、酚醛树脂和玻璃三种非金属材料上进行化学镀铜。通过正交设计进行小槽实验,以镀铜速率作为考核指标,对化学镀铜液中硫酸铜、酒石酸钾钠和甲醛的浓度与镀液pH值等参数进行优化。采用优化后的工艺条件,可在非金属材料表面获得分布均匀,颜色红亮,导电性良好,无漏镀现象的铜镀层。其中尼龙和酚醛树脂表面铜镀层结合力较好,玻璃表面铜镀层结合力较差。(3)非金属镀铜件表面三价铬电镀在表面化学镀铜的尼龙、酚醛树脂两种非金属材料上,在前文研究的基础上进行三价铬电镀实验,分析了不同阴极电流密度对镀层外观的影响。针对镀层出现的结合力差的缺点,给出了几种增强镀层结合力的改进方案。更多还原

【Abstract】 Chromium eletroplating, one of the most widely used industrial eletroplating technologies, has numerous applications in daily life and industrial fileds. The traditional plating process is completed by the hexavalent chromium plating method. However, hexavalent chromium plating has shortcomings such as low current efficiency, high energy consumption, and poor coverage capacity. In addition, hexavalent chromium is extremely harmful to the health of operating workers and environment. Therefore, it has become an inevitable trend that a new chromium plating technology will replace the traditional way.In this thesis, ammonium formate and ammonium oxalate are compounded as a complexing agent of the chloride system eletroplating solution for eletroplating trivalent chromium. The complete system has generally overcome the shortcomings of the hexavalent chromium plating technology illustrated above, with the superior performances including low toxicity, environment friendly, free from current disruption, feasibility at room temperature, etc. The experimental results show that the system used in the metal surface plating can achieve a chrome layer of bright appearance, large adhesion force and good corrosion resistance, which could basically meet the requirements for decoration and other practical use.The main work of this thesis includes the following three parts:(1) Trivalent chromium eletroplating on metal surfaceAmmonium formate and ammonium oxalate are compounded as a complexing agent of the chloride system eletroplating solution for eletroplating trivalent chromium on copper and 45 steel. Small tank experiments are conducted using the orthogonal test method with the thickness of the chrome layer taken as the assessment indicators and the optimal selection of the four process parameters, including concentrations of the two complexants in plating solution, cathode current density and plating time. Then good plating process conditions are obtained by further considering the effect of pH value and temperature of plating solution on the coating appearance. With the application of the optimized process conditions, chrome layers with bright appearance, uniform density, high purity, good adhesion and corrosion resistance on metal surface are achieved.(2) Electroless copper plating on non-metallic surfaceFormaldehyde-potassium sodium tartrate is used as plating bath to plate copper on non-metallic surface such as nylon, phenolic resins, and glass. The four parameters, which consist of pH value of the plating bath and concentrations and of the copper sulfate solution, potassium sodium tartrate solution and formaldehyde solution, are optimized with the plating rate taken as the assessment indicator. An evenly distributed, bright red-colored copper coating with good electrical conductivity and leakless plating can be achieved under the optimal process conditions. The experimental results show that the adhesion force of the copper coatings on nylon and phenolic resins surfaces are larger than that of glass surfaces.(3) Trivalent chromium eletroplating on non-metallic copper-plated part surfaceBased on the previous research in this paper, trivalent chromium eletroplating on the copper plated nylon and phenolic resins non-metallic surfaces were conducted, and the influence of current density on the appearance of the coating was investigated. Several improvement methods are proposed to enhance the adhesion force to overcome the weak adhesion of the coatings.更多还原