低共熔溶剂中镍基纳米复合镀层的电沉积可控制备及摩擦学性能研究

The poor dispersion stability of the nanoparticles in plating baths and the low codeposition content of the nanoparticles in matrix metals are two key disadvantages for the electrodeposition of nano-composite coatings from aqueous solution. In order to overcome these disadvantages, cheap and green ionic liquids - deep eutectic solvents (DES) were used as electrolytes to electrodeposit wear resistance or antifriction nickel nano-composite coatings in this project. The dispersion and stability mechanisms of various hard or lubricative nanoparticles in deep eutectic solvents are studied. The codeposition behavior and mechanism of the nanoparticles and matrix metals are investigated. The structure and constituent characteristics of the nickel nano-composite coatings are analyzed. The friction and wear properties of the composite coatings are evaluated and the relationship between the structure and constituent characteristics and properties are also elucidated. Based on these results, the intrinsic relations between preparation, structure and properties of the nickel nano-composite coatings are intentatively speculated. Finally, the electrodeposition processes are optimized to achieve the controllable preparation of the nickel nano-composite coatings with excellent wear resistance or antifriction properties. The implementation of this project could provide theoretical and experimental basis to enrich the composite electrodeposition theory and to develop the design and preparation method of high-performance metal matrix composite coating.

针对水溶液中电沉积制备纳米复合镀层存在的微粒在镀液体系中分散稳定性较差以及在镀层中共沉积量较低的关键问题，本项目采用廉价绿色的离子液体-低共熔溶剂作为复合电沉积的电解质溶液，开展抗磨或减摩镍基纳米复合镀层的可控制备及性能研究。研究各种硬质或润滑性纳米微粒在含镍离子低共熔溶剂中的分散稳定机制，探讨低共熔溶剂体系中纳米微粒与基质金属的复合电沉积行为与机理，分析镍基纳米复合镀层的结构/组分特征，评价镍基复合镀层的摩擦磨损性能，阐明镀层结构/组分特征与其摩擦磨损性能之间的构效关系。在此基础上，明确低共熔溶剂体系中镍基纳米复合镀层的制备工艺条件-结构/组分特征-摩擦磨损性能之间的关系规律，优化电沉积条件实现具有优异抗磨或减摩性能镍基纳米复合镀层的可控制备。本项目的实施可以为丰富复合电沉积理论，发展高性能金属基复合镀层材料的设计制备方法提供理论和实验依据。

电沉积是制备金属基纳米复合镀层最常用的方法之一。本项目针对水溶液中电沉积制备纳米复合镀层存在的微粒在镀液体系中分散稳定性较差以及在镀层中共沉积量较低的关键问题，采用低共熔溶剂作为复合电沉积的电解质溶液，开展了镍基/锌基纳米复合镀层的可控制备及性能研究。我们研究了SiC、SiO2、MoS2、GO等纳米微粒在低共熔溶剂中(含Ni2+或Zn2+)的分散稳定特性以及对复合电沉积行为的影响，探讨了纳米微粒与基质金属的电化学共沉积机理。结果表明，低共熔溶剂中所添加纳米微粒的性质显著影响金属离子的还原过程，其中SiC和MoS2抑制金属离子的还原过程，而SiO2和GO则可以促进金属的还原过程。低共熔溶剂中各种纳米微粒的加入对金属的形核机制则产生相同的影响，即均使金属趋于三维瞬时形核。系统研究了电沉积工艺条件对复合镀层组织结构、微粒含量和分布的影响，评价了镍基复合镀层的摩擦磨损性能以及锌基复合镀层的耐腐蚀性能，并分析了其摩擦磨损和耐腐蚀机理。根据所得镍基复合镀层的组织结构和摩擦学特性，提出了一种低共熔溶剂中原位合成纳米微粒制备复合镀层的方法。采用此方法可以制备得到纳米微粒均匀分布的复合镀层，具有比直接添加纳米微粒方法所得的复合镀层更好的摩擦磨损性能，是一种很有潜力的高性能复合镀层制备新方法。