Study on extreme sulfuration behavior of brush-electroplated silver-graphene composite coatings as the electrical contact materials for the outdoor high-voltage isolating switch

The silver-graphene (Ag-G) composite coating was successfully prepared on the copper substrate via the method of cyanide-free brush plating. When the sulfuration temperature is increased from −70 °C to 45 °C, the sulfuration degree of the Ag-G composite coating fabricated in the composite solution with the optimal graphene content of 2 g L−1 gradually increase to a maximum. With increasing the sulfuration temperature to 90 °C, the sulfuration degree of the Ag-G composite coating has a small decrease in comparison with that of 45 °C. The Ag-G composite coating achieves excellent sulfuration, abrasion and corrosive resistance under extreme sulfuration temperatures, which is superior to pure Ag coating owing to the incorporation of graphene in the bulk. The sulfuration temperature and O2 content in the Na2S solution interactively determine the sulfuration resistance. The work provides novel high-performance Ag-based coating by employing a cyanide-free composite electrolyte for the possible practical application under different extreme environments.