Co^(2+)含量对镀Ti金刚石-Ni-Co复合电沉积的影响

Effects of Co^(2+) content on Ti-coated diamond-Ni-Co composite electrodeposition

采用电镀法制备镀Ti金刚石-Ni-Co复合镀层,研究镀液中Co2+含量对镀层形貌和性能的影响,并通过电化学阻抗谱研究Ni-Co复合电沉积过程。结果表明:当镀液中未添加Co2+时,所制备的镀Ti金刚石-Ni复合镀层内凹痕较多;镀液中添加Co2+后,镀Ti金刚石-Ni-Co复合镀层内凹痕消失,晶粒均匀。随着镀液中Co2+含量的增加,所制备的镀Ti金刚石复合镀层的显微硬度先增加后减少。当镀液中Co2+含量为6%(摩尔分数)时,在-0.85V电位下Ni-Co共结晶电化学阻抗谱的电荷转移电阻最大,制备的镀Ti金刚石-Ni-Co镀层内金刚石含量最高。此外,当镀液中Co2+含量增加至8%时,镀Ti金刚石-Ni-Co复合镀层内金刚石粉体的沉积量最少。

The Ti-coated-diamond-Ni-Co coating was prepared by electroplating process. Moreover, the effect of Co2＋ content variation on the morphology and property of the Ti-coated diamond-Ni-Co coating was investigated. Meanwhile, the composite electrodeposition process was studied by electrochemical impedance spectroscopy （EIS）. The results show that there are many dents on the Ti-coated diamond-Ni coating when Co2＋ is not added in the plating bath. However, the dents disappear and the grain size becomes more uniform when Co2＋ is added into the plating bath. Moreover, with the increase of Co2＋ content in the plating bath, the microhardness of the composite coatings rises firstly and then declines. As Co2＋ content in the plating bath is 6% （mole fraction）, the charge transfer resistance of the Ni-Co codeposition evaluated from the EIS at ？0.85 V reaches the maximum value, and the content of diamond in the composite coating is the highest. In addition, as Co2＋ content in the plating bath increases to 8%, the content of diamond in the composite coatings is the least.