Effect of graphene nano-sheets additions on the density, hardness, conductivity, and corrosion behavior of Sn–0.7Cu solder alloy

Graphene nano-sheets (GNSs) are considered a functional (excellent/good) material at solder alloy modification. In this study, GNSs were doped into Sn–0.7Cu solder by powder metallurgy to form Sn–0.7Cu–xGNSs (x = 0.025, 0.05, 0.075, 0.1 wt%) composite solders. The density, hardness, and electrical conductivity of the composite solders were investigated. At the same time, Potentiodynamic polarization method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were applied to analyze the electrochemical corrosion behavior of composite solders in the 3.5 wt% NaCl solution. The results revealed that as the content of GNSs increased, the hardness of composite solders decreased, but the density enhanced when compared with original Sn–0.7Cu. Simultaneously, the conductivity reached highest as the GNSs content was 0.025 wt%. Potentiodynamic polarization showed that GNSs affected the anodic reaction of the solders. The corrosion resistance of Sn–0.7Cu–0.075GNSs was better than that of other alloys. Sn₃O(OH)₂Cl₂ and Tin oxides were the formation of the corrosion product by XPS and XRD analysis. SEM analysis confirmed that when the GNSs content was 0.075 wt%, the corrosion products were dense and the corrosion resistance of the alloy was improved.