Tuning the microstructure, mechanical properties, tribological and electrical contact behavior by Cu doping for gold-based coating

The copper phase is induced into gold coating to form nano-composition structure, which not only improves mechanical properties and wear resistance, but also remains low contact resistance. In this investigation, Au1-xCux coatings are synthesized employing magnetron co-sputtering, and the effects of Cu doping on the structural evolution, contact resistance, mechanical and tribological properties were investigated. The results show that the hardness (4.7 GPa similar to 5.2 GPa) of Au1-xCux composite coatings by incorporating 15-23 at.% Cu is more than twice as high as that of the pure Au. The achieved Au85Cu15 coating remains a good structural integrity after 3000 wearing cycles even at a large normal load of 8 N. The electrical contacts coated by Au1-xCux coatings are still in keeping with the low contact resistance (< 50 m Omega) at a low contact force of 10 gf. The finding would be interesting for guiding the development of advanced functionally coating with electrical conductivity and mechanical-tribological properties trade off.