Preparation and characterization of silver-doped graphene-reinforced silver matrix bulk composite as a novel electrical contact material

Abstract

The incorporation of graphene into silver nanopowder to prepare their bulk composite with enhanced electrical and mechanical properties is investigated. The silver-doped graphene composite (GNs–Ag) is introduced as a reinforcing phase. Silver nanopowder and GNs–Ag composite are ultrasonically mixed and plasma-sintered to prepare GNs–Ag reinforced silver matrix bulk composite. The phase structure, micromorphology, chemical state of elements of the GNs–Ag nanoparticles was analyzed in detailed. Meanwhile, micromorphology and electrical properties of the sintered bulk composites are also measured. The results showed that graphene oxide (GO) and Ag ions are simultaneously reduced by hydrazine hydrate during the reaction. Ag nanoparticles (AgNP) presents the uniformly distribution on the surface of graphene sheets. The Raman spectrum is significantly enhanced compared with that of GO due to the presence of AgNP in the GNS–Ag nanoparticles. It is observed that C/O mass ratio demonstrates an increasing trend from 1.84 in graphene oxide to 6.29 in the composites materials. Compared to International Annealed Copper Standard, this composite material possesses an electrical conductivity of 92.6%, a density of 9.59 g cm−3, and a hardness of 46.12 HV. This phenomenon can be explained as that grain boundaries will be formed at the grain boundaries of silver due to the addition of graphene. In addition, it is found that the resistance of the GNs–Ag/n-Si (111) Schottky contact is lower than Ag/n-Si (111) Schottky contact.