【作者】 王淼；

【导师】 何凤姣；

【作者基本信息】 湖南大学 ， 分析化学， 2006， 硕士

【摘要】 电沉积铁基合金具有较高的机械强度和硬度,较好的耐蚀性能,优异的磁性能和电催化活性。铁及铁盐又是最普通,最廉价的物质,如果铁与其他元素形成合金后使得它们具有更优异的物理化学性能,这将极大的降低生产成本,具有很大的应用价值。柠檬酸盐对很多金属离子有很好的络合作用,它使电镀液的稳定性,缓冲能力和抗杂质能力增强,使镀层结晶细致,性能提高;同时它的来源广泛,制备简单,价格低廉,对人体不造成危害,不污染环境,非常适合用做工业化电镀生产的络合剂。基于这两者的优点,本论文将柠檬酸盐用做电沉积铁基合金的络合剂,具体研究工作如下:1.研究了在一定工艺条件下柠檬酸盐在电沉积Fe-Ni合金中的性能行为。通过改变新配镀液中柠檬酸盐的浓度来研究镀液的缓冲能力,沉积速度,阴极电流效率,镀层中铁,镍含量及硬度、密度、耐蚀性能的变化;通过X射线衍射(XRD,X-ray Diffraction)研究了Fe-Ni合金结构的变化,从而获得该条件该体系中最佳的络合剂用量。本文使人们更清楚的了解了柠檬酸盐的作用,为工业化生产Fe-Ni合金奠定了基础。2.首次对柠檬酸盐体系中电沉积非晶态Fe-Ni-W合金镀层的性能行为进行了详细的研究。通过与铬镀层对比,研究了在干摩擦和N150号润滑油摩擦条件下该镀层的磨损性能和机理,以及该镀层在5%的NaCl,5%的H2SO4和5%的NaOH溶液中的耐蚀性能,同时利用扫描电子显微镜(SEM,Scanning Electron Microscopy)和X射线衍射观察了镀层的表面形貌及其结构。实验结果表明,该条件该体系下得到的镀层性能优于镀铬。该工艺使用的也是柠檬酸盐络合剂,它价格便宜,在电镀过程中容易维护,环保无污染,所得镀层性能优异,可以进行大规模的工业化生产,从根本上取代铬镀层。3.结合以上实验结果,应用软硬酸碱理论和配位理论,分别推测出酸碱体系下铁基合金电镀液中的柠檬酸盐络合物的可能结构;同时利用络离子迟缓放电理论和软硬酸碱理论给出了该络合物可能的放电步骤及放电过程中的活性中间体的可能结构,为铁基合金电镀液的维护和合金的生产提供了理论依据。4.针对铁基合金电镀液成分复杂,本文提出了一种测定铁基合金电镀液中柠檬酸盐含量的新方法:利用Dowex1X8-200强碱型阴离子交换树脂分离纯化电镀液中的柠檬酸更多还原

【Abstract】 Electroplating ferrous alloys had wonderful performances in its microhardness, mechanical intensity, corrosion resistance, magnetic and catalyzed active properties. Citrate used as a complexing agent was low cost and environmentally friendly. It could stabilize the electrolytes and make the crystal size of the alloy small and compact. In this paper, the behaviors of citrate in electroplating ferrous alloys were studied. The detailed research work was listed as follows:(1) The effects of citrate on Fe-Ni alloy deposits were discussed in this paper, such as the appearance, composition, density, microhardness, corrosion resistancs and adhesion ability. The effects of citrate on the electrodeposit velocity and cathodic current efficiency of the bath were also investigated. The structures of these alloy deposits from different citrate concentration electrolytes were detected by XRD (X-Ray Diffraction). The optimum citrate concentration under this condition was 0.12~0.65mol/l.(2) A new process of electroplating amorphous Fe-Ni-W alloy deposits in citrate electrolyte was proposed. Friction and wear behavior of Fe-Ni-W alloy deposit was studied and compared with that of chromium deposit. The corrosion properties against 5% sodium chloride, 5% sulfuric acid and 5% sodium hydroxide were also discussed in this paper. The structure and morphology of Fe-Ni-W alloy deposit were detected by XRD and SEM. The performances of this deposit from citrate electrolyte were better than chromium deposit. The citrate used as the complexing agent made the bath low cost and environmentally friendly. So it would find widely use in industries to replace the chromium deposit.(3) Combining with the experimental results described above, the possible structures of the citrate complexes in ferrous alloy electrolytes were proposed for the first time based on soft hard acid and basic theory and complexing theory. The possible discharging processes and active intermediate stuctures of the citrate complexes were also discussed using complex slow discharging theory and soft hard acid and basic theory.(4) A new method for quantification of citrate in ferrous alloy electrolytes was proposed. Citrate in these electrolytes was purified by Dowex 1X8-200 strong basic anion exchange resin and converted into ethyl ester with the catalyst boron trifluroride-aether. After washing更多还原