纳米晶铝和铝基合金镀层的电沉积法制备及其腐蚀电化学行为

Aluminum is an attractive coating/plating material because of its almost unlimited reserves, excellent mechanical performance, good corrosion resistance and environmentally benign characteristics. Recent investigations indicate that some nanostructured coating/plating materials with passive elements (e.g., Al, Cr, Ni) not only demonstrate obviously enhanced mechanical properties (e.g., strength and ductility), but also exhibit improved corrosion resistance. Therefore, it is of great importance to investigate the electrochemical corrosion behaviors of nanocrystalline aluminum and Al alloys. In this project, nanocrystalline aluminum and Al-based alloy film electrodes are prepared by the cathodic electrodeposition in air and water stable ionic liquids, and their electrochemical corrosion behaviors are investigated in detail. We try to probe the dependence of structure and properties of the nanocrystalline films on the electrodeposition conditions such as applied mode of potential/current, kinds of ionic liquids, composition of electrolytes and temperature. Based on these investigations, the controllable fabrication of the nanocrystalline films can be realized. The corrosion evolution behaviors of nanocrystalline aluminum and Al-based alloy films would be investigated by various electrochemical techniques and physical characterization methods. It is expected that the effects of some key factors (e.g., crystal size, alloy element, surface morphology and structure, surface conversion membrane) on the corrosion behaviors of the electrodeposited films as well as the related corrosion mechanism can be clarified.

铝具有资源丰富、机械性能优、耐蚀性好以及环境友好等特性，被视为极具潜力的涂/镀层材料。近年来的研究表明，一些金属涂/镀层材料（包括铝）的纳米化明显改进了其机械性能；而且对于易钝化金属或含有易钝化元素的合金，其在一些侵蚀性介质中的耐腐蚀性能也会得到改进。因此，开展纳米晶铝和铝基合金保护层的研究无疑具有重要意义。针对铝和铝基合金保护层的研究现状以及离子液体快速发展的情况，本项目拟在对于空气和水稳定的离子液体中采用阴极电沉积法制备纳米晶铝和铝基合金镀层，研究电沉积条件对铝和铝基合金镀层物理化学性质的影响规律，明确对镀层微结构进行有效调控的途径，弄清其电沉积过程动力学机制；研究不同纳米晶铝和铝基合金镀层在侵蚀性介质中的腐蚀及其演化行为，弄清关键因素对其腐蚀行为的影响规律，阐明纳米晶铝和铝基合金镀层的腐蚀作用机制以及稀土转化膜对纳米晶镀层的防护机制。从而为纳米晶铝和铝基合金镀层的广泛应用奠定基础。

铝具有资源丰富、机械性能优、耐蚀性好以及环境友好等特性，被视为极具潜力的涂/镀层材料。近年来的研究表明，一些金属涂/镀层材料（包括铝）的纳米化明显改进了其机械性能,而且对于易钝化金属或含有易钝化元素的合金，其在一些侵蚀性介质中的耐腐蚀性能也会得到改进。因此，开展纳米晶铝和铝基合金保护层的研究无疑具有重要意义。本项目采用在离子液体中阴极电沉积的方法制备了纳米晶铝和铝合金镀层，深入研究了其组成、结构与电化学腐蚀性能的关系。获得了如下具有创新性的研究成果。.（1）在添加2-氯烟酰氯的由氯化1乙基3甲基咪唑和氯化铝构成的离子液体中通过脉冲电沉积法制备了纳米晶铝镀层。2-氯烟酰氯的添加增加了电沉积的过电位，从而加快了电结晶的成核速率；同时添加剂在铝表面的吸附抑制了晶核的生长；这两个因素导致了纳米晶铝镀层的形成。所制备的纳米晶铝镀层呈现光亮平整的外观，显示了比微米晶铝镀层更好的耐腐蚀性能。.（2）在氯化铝型离子液体中采用电沉积法分别制备了铝和铝锰合金镀层。所制备的Al-Mn合金镀层是致密的，与基体结合良好。较高锰含量的Al-Mn合金镀层显示了较好的耐蚀性。.（3）在含有氯化锰和氯化锆的氯化铝型离子液体中采用阴极电沉积法制备了Al-Mn-Zr三元合金镀层。在含有适量氯化锆的离子液体中获得了由大小为315 m的结节性颗粒组成的致密镀层，进一步观察表明这些结节性颗粒由纳米大小的微晶组成。该三元合金镀层因具有致密的膜层结构、高度均匀的表面且与基体良好的结合，因而显示了优异的耐腐蚀性能。