Current-carrying friction behavior and wear mechanism of Ag coatings by rotary spray deposition

In this work, an innovative approach termed rotary spray deposition has been developed for the synthesis of conductive and wear-resistant silver (Ag) coatings on copper (Cu) substrates, aimed at applications in electrical contact materials. The fabricated coatings exhibited superior properties, demonstrating significantly higher hardness (140 HV) and markedly lower resistivity (1.711×10-8 Ω·m) compared to conventional silver contacts. The tribological behavior and wear mechanisms of the Ag coatings were rigorously evaluated using reciprocating friction testing under conditions of minimal load and current. Findings revealed that wear predominantly occurs through mechanisms of fatigue, abrasive, and adhesive wear. Notably, the introduction of a 2A current in conjunction with a 3N force during friction testing resulted in a stable and reduced coefficient of friction, a smoother wear track surface, and the lowest contact resistance observed, indicative of enhanced antiwear properties. This improvement is attributed to the synergistic effects of electric current and friction, leading to the formation of a nanocrystalline structural layer at the wear track. Such a layer facilitates a stable frictional contact state and enlarges the contact area, thereby achieving a stable conductive state with reduced contact resistance and, consequently, superior tribological properties.