氯化胆碱-尿素体系中锌镍合金的电沉积研究

Zinc-nickel Alloy Electrodeposition in Choline Chloride-urea System

目的探究在低共熔溶剂氯化胆碱-尿素(ChCl-Urea DES)体系电沉积Zn-Ni合金的电化学行为、成核机制和耐蚀性。方法通过循环伏安曲线测试(CV)研究了Zn-Ni合金的电化学行为,用计时电流曲线测试(CA)探究了Zn-Ni合金电沉积的形核/生长机制。使用扫描电镜(SEM)对合金镀层表面的微观形貌进行观察,结合能量色散谱仪(EDS)、X-ray衍射(XRD)以及X-ray光电子能谱(XPS)研究镀层的化学成分以及物相的组成,阻抗(EIS)测试和极化测试(Tafel)评估了Zn-Ni合金镀层的抗腐蚀性能。结果Zn-Ni合金在氯化胆碱-尿素的体系中表现出正常的共沉积,与水溶液中的异常共沉积不同。镍的含量高于锌的含量,且Zn-Ni合金的成核方式是三维瞬时成核。从扫描电镜观察的结果来看,当沉积电位从‒0.70 V负向移动时,镍含量有规律地降低,但镍始终高于锌的含量,与循环伏安结果一致。XRD和XPS分析表明,镀层中含有镍,并且确实存在Zn元素。耐蚀性的测试结果表明,在沉积电位为‒0.85 V时,制得的Zn-Ni合金镀层展示出更强的耐腐蚀性。这可能是因为该镀层结构致密,晶粒尺寸小而且在表面均匀分布。结论Zn-Ni合金在ChCl-Urea DES体系下经历扩散控制的不可逆电极过程,呈现正常共沉积,镍的含量高于锌。其成核机制为三维瞬时生长,扩散限制了生长过程。在‒0.85 V的沉积电位下镀得的Zn-Ni合金镀层由于致密性好、晶粒尺寸细小且均匀分布,具备良好的耐腐蚀性。

Zn-Ni electrodeposition is an important metal surface treatment technology.Through reasonable control of electrochemical reaction,electrodeposition conditions and electrodeposition process control,zinc-nickel alloy plating with good corrosion resistance,good wear resistance,low hydrogen embrittlement and good weldability can be obtained.There are many reports on the research of Zn and Ni alloy,in which the Ni content also affects the corrosion resistance of Zn and Ni alloy plating.In this paper,the Zn and Ni alloy plating with high Ni content was obtained at different deposition potentials,and the electrochemical behavior of Zn and Ni alloy and the corrosion resistance of the plating alloy were studied.In eutectic solvents,the electrochemical behavior,nucleation/growth mechanism,and corrosion resistance of Zn-Ni alloy plating are also affected by differences in deposition potentials during electrodeposition.The investigation aims to examine the electrochemical properties,nucleation mechanisms,and corrosion resistance of Zn-Ni alloy in Choline chloride-Urea Deep Eutectic Solvent(ChCl-Urea DES).The research delved into the electrochemical processes underlying the formation and growth of Zn-Ni alloy through cyclic voltammetry(CV)and chronoamperometry(CA)techniques.A scanning electron microscopy(SEM)was employed to scrutinize the alloy's microstructure.Furthermore,the composition and phase structure were analyzed by energy-dispersive spectroscopy(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The corrosion resistance was assessed through electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization(Tafel)tests.Results indicated that Zn-Ni alloy electrodeposition in the ChCl-Urea DES system followed conventional codeposition behavior,differing from the unconventional behavior observed in aqueous solutions.The content of nickel in the deposited layer was higher than that of zinc.The nucleation mechanism of Zn-Ni alloy was determined to be three-dimensional instantaneous nucleation based on fitting and comparison of the chronoamperometry curves.SEM results revealed that the nickel content in the zinc-nickel plating decreased regularly with a negative shift in deposition potential,while the content of nickel remained higher than that of zinc throughout the deposited layer,which was consistent with the cyclic voltammetry results.XRD analysis indicated the presence of nickel in the zinc-nickel plating,with a possible small amount of zinc.XPS results confirmed the presence of zinc in the plating.Tafel and EIS tests demonstrated that the Zn-Ni alloy plating obtained at a deposition potential of–0.85 V exhibited good corrosion resistance.In conclusion,zinc-nickel alloy has experienced diffusion-controlled irreversible electrodeposition in the ChCl-urea DES system,which is different from the abnormal co-deposition in aqueous solution.In the ChCl-urea DES system,metal zinc deposition shows normal co-deposition behavior;and the content of nickel is higher than that of zinc.In the process of zinc and nickel co-deposition into zinc-nickel alloy,a three-dimensional transient nucleation mechanism occurs.The Ni content in zinc-nickel alloy plating can be regulated by controlling the deposition potential.The nickel content gradually decreases as the deposition potential moves in a more negative direction.When the deposition potential is transferred from–0.70 V to–0.85 V,the Ni content decreases when the deposition potential is further negative to–0.90 V.When the deposition potential is–0.85 V,the zinc-nickel alloy plating has significant corrosion resistance,probably due to its dense structure,fine-grain texture,and uniform surface distribution.