Current-carrying tribological properties of Ag composite coatings: Role of nanodiamonds in friction-induced plastic deformation

Nanodiamonds (NDs) reinforced sliver (Ag) composite coatings were successfully developed on copper substrates by a novel chemical spray deposition technique. The effects of NDs on grain plastic deformation and current-carrying tribological properties were comprehensively analyzed. The findings reveal that NDs are uniformly dispersed alone Ag grain boundaries, forming strong interfacial bonds with the Ag matrix. This interfacial bonding anchors the grain boundaries, effectively restraining their migration and deformation due to the high hardness. Additionally, the presence of NDs promotes the accumulation of high-density dislocations near grain boundaries, which act as nucleation sites for recrystallization and formation of numerous twins. The synergistic effects of the load transfer capacity of NDs and their deformation-hindering characteristics significantly enhance the current-carrying wear resistance of the Ag composite coatings . • Enhancing mechanism of nanodiamonds on antiwear properties in Ag coatings has been revealed. • The interface between nanodiamonds and Ag grains can hinder grain deformation. • No cracks or holes were found at the heterogeneous interface to disperse frictional load transfer. • A large number of dislocations are accumulated within Ag grains.