电流密度和铜离子浓度对电沉积Cu-Ni镀层性能的影响

Influence of Current Density and Copper Ion Concentration on Properties of Electrodeposited Cu-Ni Coatings

摘要:

研究了一种简单、高效、环保的防腐技术，通过在工件表面沉积Cu-Ni合金涂层来阻止腐蚀介质，从而保护碳钢表面免受腐蚀。使用扫描电子显微镜、X射线能量色散光谱、维氏硬度计、摩擦磨损试验机和电化学测试研究了电流密度和Cu²⁺浓度对涂层成分、形态和组成的影响。结果表明，涂层表面出现花椰菜状富镍突起结构。较低的电流密度和Cu²⁺浓度通过影响晶粒微观结构和Cu/Ni含量来影响涂层的维氏硬度和耐磨性，从而导致硬度和耐磨性能的降低。当电流密度为10 mA·cm^–2，Cu²⁺浓度为0.1 mol·L^–1时，沉积样品的腐蚀电流密度达到1.389×10^-5 A·cm^–2。经过24 h的盐雾试验后，镀层表面腐蚀损伤明显小于未覆盖镀层样品。对沉积机理的研究表明，Cu²⁺在扩散控制下经历瞬时形核，倾向于垂直生长并形成花椰菜状突起，而Ni²⁺则受电化学控制，在表面均匀放电。

Abstract:

A straightforward, highly effective, and environmentally friendly technique was investigated for protecting carbon steel surfaces from corrosion, i. e., depositing Cu-Ni alloy coatings on the workpiece's surface to impede corrosive medium. The effects of current density and copper ion concentration (Cu²⁺) on the composition, morphology, and properties of the coating were analyzed using scanning electron microscope, X-ray energy dispersive spectrometer, Vickers hardness tester, friction and wear tester, and electrochemical testing. Results show that a cauliflower-like Ni-rich protrusion structure appears on the coating surface. The lower current density and Cu²⁺ concentration affect the Vickers hardness and wear resistance of the coating by altering the microstructure and Cu/Ni content, both leading to a decrease in hardness and wear resistance. When the current density is 10 mA·cm^-2 and the Cu²⁺ concentration is 0.1 mol·L^-1, the corrosion current density of the deposited sample reaches 1.389×10^-5 A·cm^-2, and its surface corrosion damage is reduced compared to the uncoated sample after 24 h of salt spray test. Research on the deposition mechanism indicates that Cu²⁺ undergoes instantaneous nucleation under diffusion control, tending to grow vertically and form cauliflower-like protrusions, while Ni²⁺ is discharged uniformly across the surface under electrochemical control.