Mg-3.0Nd-0.2Zn-0.4Zr镁合金表面电沉积Cu镀层及其耐腐蚀性能

摘要

To improve the corrosion resistance, electrodeposition of Cu coating on Mg−3.0Nd−0.2Zn−0.4Zr (mass fraction, %NZ30K) magnesium alloy via an appropriate pretreatment was investigated. The surface morphologies, compositions and microstructures of the pretreated films and Cu coating were characterized in detail. The results show that the activation film consists of fluoride and phosphates and Zn immersion film forms preferentially on the eutectic compound Mg12Nd phase region. A smooth, uniform and dense Cu coating is successfully obtained. Potentiodynamic polarization tests reveal that Cu coating can greatly improve the corrosion resistance of NZ30K magnesium alloy. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests during long-term immersion further demonstrate that Cu coating can provide an effective protection for NZ30K magnesium alloy from corrosion up to ~60 h, due to its dense structure and a stable passive film formed. In addition, Cu coating exhibits good adhesion to substrate as confirmed by thermal shock test.%研究Mg−3.0Nd−0.2Zn−0.4Zr(NZ30K)镁合金上电沉积Cu镀层的前处理过程及耐腐蚀行为。研究结果表明：活化膜和浸锌层均优先在Mg12Nd共晶相表面沉积。Cu镀层能够为镁基体提供长达60 h的防护作用，这主要归因于其致密的镀层结构及浸泡过程中形成较稳定的钝化膜。热震试验证明镀层具有良好的结合力。