Surface Property Modification of Copper by Nanocomposite Coating

Abstract

Copper has high electrical and thermal conductivities, good corrosion resistance at ambient temperature, excellent malleability/workability and reproducibility, apart from these it is cheap and abundantly available metal other than good conducting metals like Silver. But has poor mechanical properties such as hardness and wear resistance. Some applications like Contacts in electrical switches necessitate the improvements in the mechanical properties without much loss of electrical and thermal conductivities. Bulk modification / alloying have been tried but limitations in alloying and adversely decrease in its electrical and thermal conductivities has been reported. Another way to improve its mechanical properties is with Surface modification by developing composite coating on its surface. In the present work we employed Electrodeposition process to develop a composite coating with Cu matrix and Ceramic oxide particles TiO2 (particle size ~202 nm), Al2O3 (particle size ~287 nm) as reinforcements. The coatings were developed with 10 g/l, 30 g/l and 0 g/l (unreinforced) concentrations in bath, at four different current densities (5, 8, 11, 14 A/dm2) with using copper sulfate bath in order to study the effect of Current density and particle concentration in bath, on structure and properties of the coatings developed. The crystallite size was averagely 50-65 nm and a strong (220) texture was obtained in composite coatings and unreinforced Cu coatings determined from the XRD data. The composition and surface morphology of coatings were studied by using EDS and SEM. Hardness and Wear resistance of the coatings were determined by using microhardness tester and ball on plate wear tester, improved hardness and wear resistance of composite coatings were observed compared to the unreinforced copper coatings.