On the Production & Tribo-Electrical Characterization of Carbon Nanotube-Reinforced Ag & Cu Metal Matrix Composites

Silver and copper are among the best metallic conductors, however, there are other aspects in which these contact materials could be improved on to enhance electrode performance; namely, thermal stability, mechanical properties, atmospheric protection, among others. In this work, carbon nanotube (CNT)-reinforced metal matrix composites (MMC) are sintered via powder metallurgy – seeking to achieve the highest MMC density possible – at two reinforcement phase concentrations, i.e., 0.5 and 1 wt.%. Through the reinforcement phase it is sought to improve wear performance of the electrode without affecting the bulk materials’ conductivity. The densified MMC were characterized via load dependent and current dependent electrical contact resistance (ECR), as well as evolution of ECR during fretting tests. Further characterization focuses on fretting mark morphological and chemical analysis via electron microscopy and spectroscopy, as well as confocal laser microscopy. As the weight percentage of the reinforcement phase increases, an increase in load dependent ECR was observed; nonetheless, contact reproducibility increases. The addition of CNT into the metallic matrices also promoted a reduction in adhesive wear. Moreover, when observing the ECR evolution during fretting, the reinforced samples rapidly reached steady-state ECR, remaining constant throughout the entire duration of the fretting test.