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

Abstract

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 ∼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 mΩ) 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.