Ni-Co/ZrO2复合共沉积过程的电结晶行为

为了研究Ni-Co-ZrO_2复合镀层电结晶初期的共沉积行为,在酸性氨基磺酸盐体系中采用阴极扫描伏安和计时电流等电化学测试方法,通过电化学反应动力学参数计算揭示Ni-Co-ZrO_2复合镀层成核机理。结果表明:Ni-Co合金镀液中ZrO_2纳米粒子的添加使共沉积电位正移,降低了阴极极化度。Ni-Co合金和Ni-Co-ZrO_2复合镀层的形核/生长过程符合受扩散控制的Scharifker-Hill瞬时成核模型,在低负电位下,Ni-Co-ZrO_2复合镀层成核弛豫时间减少,成核速率更高,电极表面吸附的ZrO_2纳米粒子促进了基质金属的成核及生长;高负电位下,复合镀层体系的峰值电流略低于合金体系,且成核速率降低,ZrO_2纳米粒子在电极表面表现出空间位阻效应,抑制了基质金属的电结晶过程。

Electro Crystallization Behavior of Ni-Co/ZrO2 Composite in Codeposition Process

To study the codeposition behavior of Ni-Co-ZrO₂ composite coatings in the initial stage of electro crystallization, cathodic voltammetry and chronoamperometry test methods were used in an acidic amino sulfonate system, and the nucleation mechanism of Ni-Co-ZrO₂ composite coating was revealed by calculating electrochemical kinetic parameters. The results show that the presence of nano particles in the bath resultes in a positive shift of Ni-Co reduction potential and reduces the cathodic polarization. The nucleation and growth process for Ni-Co alloy and Ni-Co-ZrO₂ composite coatings is closer to the Scharifker-Hill instantaneous nucleation model with diffusion controlled mechanism. The nucleation relaxation time of Ni-Co-ZrO₂ composite coating becomes shorter at low potentials, the nucleation rate becomes higher, and the addition of ZrO₂ nanoparticles in bath promotes the nucleation and growth of the matrix metal. The peak current of the composite system at high potential is slightly lower than that of the alloy bath, the nucleation rate decrease, and ZrO₂ nanoparticles on the surface of the electrode inhibit the electro crystallization process of metal matrix because of its steric effect.