DMH对氯化胆碱-乙二醇体系电沉积银的影响

Effect of DMH on electrodeposition of silver in choline chloride-ethylene glycol bath

[目的]研究5,5-二甲基海因(DMH)作为添加剂对氯化胆碱-乙二醇(ChCl-EG)低共熔溶剂体系中银电沉积的影响。[方法]采用循环伏安法(CV)和计时电流法(CA)研究了DMH浓度对Ag还原行为和成核的影响。通过X射线衍射仪(XRD)、扫描电镜(SEM)及能谱仪(EDS)探究了DMH浓度对Ag镀层晶相结构、微观形貌和元素组成的影响,并通过塔菲尔极化曲线测试考察了DMH浓度对Ag镀层耐蚀性的影响。[结果]随着镀液中DMH的添加及其浓度的增大,银电沉积的还原(峰)电位负移,还原峰电流密度略降;在电沉积初期银的成核更接近三维瞬时成核模型,但随着时间的推移逐渐偏离三维瞬时成核模型和三维连续成核模型;镀液中添加DMH可令Ag镀层晶粒得以细化,表面形貌有所改善。DMH浓度为0.8 mol/L时所得Ag镀层最为致密,晶粒细小,耐蚀性最佳。[结论]DMH作为ChCl-EG体系的添加剂能够显著提高Ag镀层的性能。

[Introduction]The effect of 5,5-dimethylhydantoin(DMH)as an additive on the electrodeposition of silver in choline chloride-ethylene glycol(ChCl-EG)deep eutectic solvent(DES)needs to be studied.[Method]The effect of DMH concentration on the reduction behavior and nucleation of Ag was studied by cyclic voltammetry(CV)and chrono-amperometry(CA).The phase structures,micromorphologies,and elemental compositions of the Ag coatings electro-deposited at different DMH concentrations were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy-dispersive spectroscopy(EDS),and their corrosion resistance were examined through Tafel polarization measurement.[Result]With the addition of DMH and the increasing of DMH concentration,the reduction(peak)potential of silver electrodeposition was shifted towards the negative direction,and the reduction peak current density was slightly decreased.At the initial stage of electrodeposition,the nucleation of silver was close to the three-dimensional instantaneous nucleation model,but it gradually deviated from both the three-dimensional instantaneous nucleation model and the three-dimensional continuous nucleation model with the extending of time.The addition of DMH to the DES could refine the grain of Ag coating and improve its surface morphology.The Ag coating electro-deposited with 0.8 mol/L of DMH featured the most compact microstructure,the finest grains,and the best corrosion resistance.[Conclusion]DMH can be used as an additive for ChCl-EG DES to improve the properties of Ag coating.