Surface modification of electrical contacts by cold gas dynamic spraying process

This study aims at improving mechanical properties of electrical contacts through copper and copper matrix silicon carbide reinforced composite coatings produced by cold gas dynamic spraying coating and heat treatment. Characterization of coatings was made by microstructural investigations, electrical conductivity measurements and mechanical tests. Microstructural evaluations have shown that coatings adhere to the substrate without any discontinuity at the interface and ceramic particles distribute uniformly. XRD analyses have revealed that there are no other phases rather than constituents of feedstock powder mixtures. Cold sprayed coatings exhibited much higher hardness and lower electrical conductivity when compared with those of Cu substrate. In general cold sprayed coatings showed better wear performance when compared with Cu substrate. Composite coatings unexpectedly exhibited poor wear performance when compared with that of unreinforced Cu coating. Heat treatment significantly reduced the hardness and wear rate of the coatings as well as increased the electrical conductivity of the coatings.