Surface Modification of Copper by Electro-codeposition

Abstract

Copper has good electrical and thermal conductivity which makes it useful for engineering and thermal applications. But its poor mechanical property necessitates strengthening of the same without adversely affecting its electrical conductivity for its use in electrical applications. Surface engineering approach does not adversely affect the bulk properties and among various such techniques, electro-codeposition technique is considered cost effective due to its simple operation, high production rate and capability to handle complex geometry.
The objective of the dissertation is to improve the surface mechanical properties of Cu by electro-co-deposition of Cu based different oxide nanoparticles (Al2O3, SiO2, Y2O3, ZrO2 and graphene oxide (GO), reduced graphene oxide (RGO), thermally reduced graphene oxide (TRGO)) dispersed composite coating on it by direct current (DC) and pulse current (PC) mode without much deteriorating the electrical conductivity. Cu-Al2O3 composite coatings were prepared with varying current density (5, 8, 11 and 14 A/dm2) and Al2O3 content, whereas, Cu-SiO2/Y2O3 was prepared at different pulsing condition (1, 5 and 10 kHz frequency) and Cu-ZrO2 were studied with different surfactant addition. Detailed texture study of Cu-SiO2/Y2O3 coatings was also carried out along with oxidation behavior of Cu-Y2O3 coating. Cu-GO/RGO/TRGO coatings were also analyzed for the optimum coating parameters. Coatings were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), microhardness testing, wear testing, electrical conductivity study etc.
When results of the each system was analyzed, it was observed that the better surface-mechanical property obtained was due to finer matrix, better dispersion and favorable crystallographic orientation. These were obtained with specific current density/ pulsing condition/ second phase amount. Electrical conductivity was found to be dependent mainly on matrix fineness and dispersion fraction. Better surface mechanical properties leads to marginal deterioration of electrical conductivity but the values obtained in the present study was in the acceptable range of commercial application.