Surfactant-assisted electrodeposition of Au–Co/WS2 self-lubricating coating from WS2 suspended cyanide electrolyte

Abstract

In this study, Triton X-100 was used as the WS2 dispersion agent in the Au–Co cyanide electrolyte to deposit Au–Co/WS2 composite coatings. Probe sonication was applied to exfoliate the commercial WS2 powders to produce thinner and smaller WS2 flakes, which improved the stability of the WS2 particles in the electrolyte. According to the electrochemical analyses, the effects of adding Triton X-100 and WS2 particles to the electroplating process were investigated. Through material characterizations, WS2 particles were proved to be compounded into the Au–Co matrix and showed clearly {002} preferred orientation due to their flake structures. Tribological tests were performed under dry condition in 10−3 Pa vacuum against stainless steel 316L balls with diameters of 3 mm and a normal contact force of 2 N. The Au–Co/WS2 composite coatings that developed showed the minimum coefficient of friction and wear rate of 0.05 and 8 × 10−6 mm3/N·m, which are 5 times and 3 times lower than the Au–Co reference coating, respectively.