Electrochemical action of particles in Ni-diamond composite electrodeposite baths

Based on the study about cathodic potentiodynamic diagrams, electrochemical impedance spectroscopys and differential capacitance curves for pure Ni and Ni-diamond electrodeposition systems, the effect of diamond particles on diffuse double layer was investigated. And so the electrochemical action of particles in Ni-diamond composite electrodeposition was discussed. The results show that polarizability of the composite system is smaller with the addition of diamond particles. At the same time Faraday resistance of the composite system is bigger, electric double layer capacitance is smaller and the differential capacitance value is obviously lower, compared with pure Ni system. Further analysis indicates that fraction of coverage θNF which has an effect on Non-Faraday admittance could reflect more efficiently the content of particles in the composite compared with the fraction of coverage θF interfered with Faraday admittance. Cathodic surfaces are negative charge near deposition potentials for both Ni and Ni-diamond electrodeposition systems. But negative charge density of the composite system is less than 1/200 of that of pure Ni system. Copyright © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved