2022 年 61 巻 1 号 p. 195-199
This study is aimed at fabricating Sn–Graphene composite films on Cu alloys by hybrid electroplating method and clarifying the factors that affect the properties as automotive connectors. The graphene content in composite films was dependent on the current density during electroplating as well as graphene size. It was confirmed from GD–OES and Raman analysis that graphene exists not only on the outermost surface but also inside the composite films, with better crystallinity for the larger size or domain. The Sn–Graphene composite film exhibited lowest electrical contact resistance of 0. 61 mΩ (0.5 Ν), which reduced 32–34％ compared to pure Sn plating films due to the high conductivity of the graphene in the Sn film. In particular, the contact resistance value of Sn–Graphene composite film remained much lower than that of pure Sn film even after heat resistance test at high temperature above 200 °C for more than 70 h. This is because the graphene sheets suppressed effectively the Cu–Sn alloying progress of the plating film during heating. Moreover, it is found from fretting corrosion tests that the Sn–Graphene (3–5 mm) exhibited excellent stability with unchanged contact resistance upon sliding, in comparison to the significant increase for pure Sn film in a short period, which can be attrubuted to the inclusion of graphene in the wear powder between the connectors.
