低孔隙率HEDP镀铜工艺及镀层性能研究

发布时间：2018-04-28 09:50

本文选题：HEDP + 孔隙率　；参考：《南昌航空大学》2017年硕士论文

【摘要】：酸性硫酸盐、焦磷酸盐等镀铜工艺由于镀层结合力差、孔隙率高等缺点,无法满足航空企业对镀铜层性能多样化的要求,因此,我国航空企业镀铜工艺目前依然以含剧毒氰化物的氰化镀铜工艺为主,而HEDP镀铜工艺能够在钢铁件上直接电镀,镀液深镀能力好,电流效率高而广受关注。针对镀铜层孔隙率高的缺点,在HEDP镀液中加入添加剂A、B,研究其阴极极化作用、润湿作用、整平作用,确定添加剂的适宜浓度,同时辅助施加阴极移动降低镀层孔隙率,并从镀液和镀层性能角度,将HEDP镀铜与氰化镀铜工艺进行综合比较;采用滴定分析方法测试了HEDP镀铜液中Cu~(2+)、HEDP含量随通电量的变化,并依据工艺要求进行调整维护;采用电化学等试验方法,比较不同钝化工艺对HEDP镀铜层耐蚀性的影响,并对其机理进行初步探讨。主要研究结果如下:在HEDP镀铜基础液中加入0.4 g/L添加剂A和2 mg/L添加剂B,添加剂的吸附作用使得极化电位提高,阻化铜的沉积并使晶粒得到细化,添加剂A能够降低镀液的表面张力和固液界面自由能,增强镀液对阴极界面的润湿能力,有利于镀液在试样表面的铺展,从而有效抑制析氢反应,同时辅助施加3 cm/s的阴极移动,缩短了氢气泡在试样表面的滞留时间,加速氢气泡的脱附逸出,避免了较大尺寸针孔和麻点的形成,镀层内部组织连续、结构致密。当镀层厚度仅8μm时孔隙率便可为0,而在相同的镀层厚度下,氰化镀铜及其他无氰镀铜工艺均有较高的孔隙率。HEDP镀铜溶液的深镀能力、分散能力均达到或超过氰化镀铜工艺的水平,尤其阴极电流效率远高于氰化镀铜工艺,此外,进行渗碳热处理时,HEDP镀铜层厚度约15μm,便可有效防止碳的扩散渗透,明显优于氰化镀铜工艺,其根本原因在于镀液电流效率高、镀层孔隙率低且结合力好。30CrMnSiNi2A试样经HEDP镀铜工艺处理后的氢脆性能合格;HEDP镀铜工艺对30CrMnSi A试样疲劳寿命的影响程度与氰化镀铜工艺相当。对于1 L的HEDP镀铜溶液,随着通电量的增大,镀液中Cu~(2+)含量基本稳定,络合剂HEDP会发生水解导致含量下降,通电量增大约100 A·h需对HEDP进行补加调整,镀液性能稳定,维护方便。因此,HEDP镀铜工艺能够用来替代现行氰化镀铜工艺。采用HAD无铬钝化工艺,镀铜层耐蚀性优于六价铬钝化,其耐蚀性的提高与钝化膜致密度提高、膜层结构得到完善有关。
[Abstract]:Due to the poor adhesion and high porosity of copper plating process such as acid sulfate and pyrophosphate, it can not meet the requirements of aviation enterprises for the diversification of copper coating performance. At present, the copper plating process of aviation enterprises in China is still mainly cyanide copper plating process, while HEDP copper plating process can be directly electroplated on iron and steel parts, the deep plating ability of bath is good, and the current efficiency is high and widely concerned. Aiming at the disadvantage of high porosity of copper plating layer, the additive Abib was added to HEDP bath to study the effect of cathodic polarization, wetting and leveling, to determine the appropriate concentration of additives, and to apply cathodic movement to reduce the porosity of coating. From the point of view of bath and coating properties, the copper-plating process of HEDP was compared with that of cyanide, the content of Cu~(2 in HEDP copper plating bath was measured by titration analysis method, and the content of Cu~(2 was adjusted and maintained according to the requirements of the process. The effects of different passivation processes on the corrosion resistance of HEDP copper coating were compared by electrochemical and other experimental methods, and its mechanism was preliminarily discussed. The main results are as follows: when 0.4 g / L additive A and 2 mg/L additive B were added to the base solution of HEDP copper plating, the adsorption effect of the additive increased the polarization potential, prevented the deposition of copper and refined the grain size. Additive A can reduce the surface tension and the free energy of solid-liquid interface, enhance the wetting ability of the bath to the cathode interface, facilitate the spreading of the bath on the surface of the sample, thus effectively restrain the hydrogen evolution reaction. At the same time, the cathode movement of 3 cm/s can shorten the retention time of hydrogen bubble on the sample surface, accelerate the desorption escape of hydrogen bubble, avoid the formation of large size pinholes and pockmarks, the internal microstructure of the coating is continuous and the structure is dense. When the coating thickness is only 8 渭 m, the porosity can be 0. Under the same coating thickness, both cyanide copper plating and other cyanide copper plating processes have higher porosity. The dispersion ability of the copper plating process reached or exceeded the level of cyanide copper plating process, especially the cathodic current efficiency was much higher than that of the cyanide copper plating process. In addition, the thickness of copper coating of HEDP was about 15 渭 m during carburizing heat treatment, which could effectively prevent the diffusion and penetration of carbon. It is obviously superior to the cyanide copper plating process, and the fundamental reason is that the bath current efficiency is high. The hydrogen embrittlement properties of 30CrMnSiNi2A sample treated by HEDP copper plating process are equal to that of cyanide copper plating process. The effect of HEDP copper plating process on fatigue life of 30CrMnSi A specimen is equal to that of cyanide copper plating process. For 1 L HEDP copper plating solution, the content of Cu~(2 in the solution is basically stable with the increase of the amount of electricity, and the content of HEDP decreases due to the hydrolysis of the complex agent HEDP, and the increase of the current content of the solution is about 100A h, and the performance of the plating solution is stable. Maintenance is convenient. Therefore, HEDP copper plating process can be used to replace the current cyanide copper plating process. The corrosion resistance of copper coating is better than that of hexavalent chromium passivation by HAD without chromium passivation process. The improvement of corrosion resistance is related to the improvement of passivation film density and the perfection of film structure.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ153.14

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