Enhancing mechanisms of arc‑erosion resistance for copper tungsten electrical contact using reduced graphene oxides in situ modified by copper nanoparticles

To solve critical issues of premature failure for copper tungsten (CuW) based electrical contacts during arc erosion at the moment of arc breakdown, we proposed a new strategy of using metal doped reduced graphene oxides (rGOs) and in-situ formed tungsten carbides to inhibit movements of cathode spots during the arc ablation process. CuW composites were reinforced with Cu modified rGO nanopowders (i.e. Cu@rGO) using combined processes of chemical co-reduction, ball milling and spark plasms sintering (SPS). Effects of Cu@rGO addition on microstructure, arc erosion resistance and arc ablation resistance of the CuW composites were systematically investigated. Results showed that tungsten carbides with irregular shapes were formed through in-situ reactions of rGO and tungsten during the SPS process. Arc erosion resistance of 6 CuW composites was significantly improved owing to introduction of nanostructured Cu@rGO. Compared with those of CuW composites, the ablation areas of Cu@rGO/CuW ones were much smaller and the ablation craters were shallower, and the average strengths of dielectric vacuum breakdowns of the CuW composites with 3 wt% Cu@rGO were increased by 28.9%. The arc breakdown mechanisms of Cu@rGO/CuW composites were identified as: (1) The nanostructured Cu@rGO increases the viscosity of molten metal Cu, thus inhibiting its fast flow and splashing; (2) Lower work functions of carbon (i.e. rGO) and tungsten carbide restrain the electron emissions during arc breakdown; and (3) The tungsten carbides with their good stability and high melting point shorten the solidification time of molten copper liquid and extend the service life time of the Cu@rGO/CuW composites.