Mg-Al合金表面单浴离子液体中电沉积Cu/Ni-Cu纳米多层膜的应用基础研究

It is difficult for magnesium alloys to be electroplated or electroless plated with metallic coationgs in a way of reproductivity and stability due to the high chemical activities of magnesium(standard electrode potential is -2.37V).In order to overcome the difficulties of electroplating or electroless plating on magnesium alloys in aqueous solutions and to explore new solutions, this project developed a new kind of pretreatment method to adjust and control the surface composition and potential of Mg-Al alloy; and then uses choline chloride-urea ionic liquid (IL) possessing high chemical stability, a wide electrochemical window, relatively low price and green environmental as solvent to electrodepostion Cu/Ni-Cu nano-multilayer film. The Cu/Ni-Cu nano-multilayer films possessing good adhesion, high wear and corosion resistance, high electroconductivity and heat conducting property are prepared by using electrochemical deposition method and controlling the wave form of pulse voltage or pulse current in a single bath of IL of choline chloride-urea on Mg-Al alloy with high efficiency.The main research contents include:(1)The adjustment and control of surface composition and electrode petential of Mg-Al alloy and the preparation of base layer;(2) Separately electrodepostion of Cu, Ni, Ni-Cu alloy films and the nucleation and growth mechanism of Cu/Ni-Cu nano-multilayer films; (3)The effects of temperature of IL,water content,additives, such as nicotinic acid, phytic acid, EDTA etc. on the morphology, structure and mechanical properties of Cu/Ni-Cu nano-multilayers. The investigation of mechanism of high corrosion resistace, residual stress and superlattice structure and so on of Cu/Ni-Cu nano-multilayer films is carried out. This research can start a new way for electrodepositon high performance metallic coating on magnesium alloy and lay bases for the development of functional magnesium alloys. As a result, it has very important scientific research value and significance.

镁的高化学活性（电极电位为-2.37 V）使镁合金在传统水溶液中电镀或化学镀时存在许多困难，难以稳定地获得高耐蚀性金属镀层。为探索解决该问题的新方法，本项目通过对镁铝合金进行表面成分和电位均匀化预处理，采用电化学方法在单浴氯化胆碱-尿素离子液体中调控所施加的脉冲电压或电流，在镁铝合金表面高效率沉积结合力好、耐磨和耐蚀性能优异、导电性和导热性高的Cu/Ni-Cu纳米多层膜。主要研究内容包括：镁铝合金表面成分和电位均匀化处理及预沉积层生长原理；离子液体中电沉积单层Cu、Ni、Ni-Cu合金以及Cu/Ni-Cu纳米多层膜的形核和生长机制研究；吸水性（或水含量）、添加剂和温度等对Cu/Ni-Cu纳米多层膜形貌、组织结构和力学性能的影响规律；Cu/ Ni-Cu纳米多层膜高耐腐蚀性机理、膜层应力和超晶格结构的研究等。本项目可为镁合金高性能纳米晶电镀层的制备开辟新的途径，为功能镁合金的开发奠定理论基础。

本项目的研究背景是镁合金在传统水溶液中电镀或化学镀时存在许多困难，难以稳定地获得高耐腐蚀性的金属镀层。本项目就是为解决这一技术难题探索新的技术路线和途经。主要研究内容如下：.① Mg-Al合金表面成分和表面电位均一性调控研究。.② Cu2+, Ni2+在氯化胆碱-尿素离子液体中的电化学沉积行为及其形核和生长机制的影响规律。.③ 单浴氯化胆碱-尿素离子液体中电化学沉积高性能单层Cu、单层Ni镀层的工艺条件、微观组织结构和耐腐蚀性机理的研究。.④ AZ91D镁合金在“Ni-Cu 镀液”中电沉积Cu/Ni-Cu纳米多层膜的研究。.⑤ 添加剂和电流密度对在离子液体中制备Ni-Mn膜层电沉积机理、膜层成份与性能的影响。.⑥ Mg-Al合金表面高红外发射率高导电性Zn-Ni膜层的应用基础研究。.⑦ AZ91D镁合金表面Cu-Ni/Ni-Cu纳米多层膜脱合金化法制备纳米多孔膜及其光谱吸收性能的研究。..重要成果和科学意义如下：.（1）发明了去除Mg-Al合金中相的表面成分和电位均一化前处理技术。.（2）阐明了Cu和Zn预沉积层的生长原理和机制。揭示了镀液配方、工作温度、离子扩散速率、电流密度、沉积电位、添加剂及水含量等条件下Cu2+，Ni2+的阴极电化学沉积行为及动力学机制。.（3）建立和优化了制备Cu/Ni-Cu 纳米多层膜的浓度、温度、添加剂等条件与其微观组织结构、膜层硬度和膜层高耐腐蚀性机理的关系。.（4）获得了电流密度大小和波形等对单层膜的生长速度和Cu/Ni-Cu纳米多层膜晶体结构的影响规律。所制备的单层纳米晶镍Ni膜层在3.5 wt.% NaCl 溶液中的耐腐性能高达336h 。.（5）围绕Mg合金产品高红外发射率、高导电性热控膜层的应用需求，利用所研发的Cu-Ni/Ni-Cu纳米多层膜，在双电级体系下进行恒电流脱合金处理，获得了具有连续网状微观结构的Ni-Cu纳米多孔膜。该膜层在紫外、可见、近红外三个波段的平均吸光率峰值依次为97.25%，96.87%，94.88%。.（6）发表SCI/EI论文11篇；申请发明专利1项；培养博士2名，硕士生2名。..本项目圆满完成了项目计划书的各项研究工作，取得了一系列重要的研究成果，成功解决了项目计划拟解决的关键科学问题，实现了项目预定的研究目标。