Electrophoretic Deposition of Cu-SiO₂ Coatings by DC and Pulsed DC for Enhanced Surface-Mechanical Properties

The present study explored the possibilities of improvement in the surface-mechanical properties of electrodeposited Cu-SiO₂ composite coating and its underlying mechanism. Composite coatings were developed using SiO₂-dispersed acidic copper sulfate electrolyte by direct current and pulse-current electro-codeposition techniques with variation of pulse frequencies at a fixed duty cycle. X-ray diffraction analysis of the coatings revealed information regarding the presence of various phases and crystallographic orientations of the deposited Cu matrix. Scanning electron microscopy and energy dispersive x-ray spectroscopy techniques were used to investigate the surface morphology and chemical composition of the coatings, respectively, and it was observed that SiO₂ particles were uniformly distributed in the composite coatings. Surface roughness was found to be reduced with the increasing pulse frequency. The Vickers microhardness and ball-on-plate wear study showed improvement in surface-mechanical properties due to the formation of fine Cu matrix, dispersion strengthening due to homogeneously distributed SiO₂ particles, and the preferred orientation of the Cu matrix. Marginal decrease in electrical conductivity with the increasing SiO₂ content and pulse frequency was observed from the four-probe electrical conductivity measurement technique.