The effect of current density on microstructural homogeneity, hardness, fracture toughness and electrochemical behavior of electrodeposited Cu-0.5Co/WC nano-composite coating

Abstract

The Cu-0.5Co/WC nano-composite coating was synthesized on CP-copper substrate using direct current (DC) electrodeposition method. At this work, it was tried to increase the hardness of surface without considerable degradation of copper's particular physical properties such as electrical conductivity. The effect of current density on microstructural homogeneity, hardness, fracture toughness and electrochemical behavior of coating was investigated. The copper plates with the purity of 99.99% were used as electrodes. The electrolyte consists of tungsten carbide particles (30 g/l), copper sulfate (200 g/l), sulfuric acid (50 g/l), cobalt sulfate (50 g/l) and sodium dodecyl sulfate (SDS) (0.3 g/(g of WC)) as surfactant. The particle size of tungsten carbide powder was in the range of 40-70 nm. The distribution of tungsten carbide particles in coating was studied using FESEM. Micro-hardness measurement was performed in Vickers scale. The fracture toughness of coating was determined by Vickers indentation test. The corrosion resistance of the electrodeposited Cu-Co and Cu-Co/WC nano-composite coatings was evaluated by polarization studies. Referring to results, the use of optimum current density value (60 mA/cm2) during the electrodeposition process improves hardness and corrosion resistance of nano-composite coating. Additionally, Cu-Co/WC composite coating shows more corrosion resistance than the unreinforced one.