Response mechanism of interfacial spacing driven load induced tribological behavior and charge density evolution for C/Cu fretting

Fretting is a major failure mode in electronic connectors within micro-electro-mechanical systems (MEMS). Understanding the friction-induced changes in interfacial electronic properties and their link to the structural evolution of diamond‑copper composites is crucial for controlling fretting in practical applications. This study examines the charge density evolution Δρ at the C(111)/Cu(111) interface and its intrinsic correlation with fretting performance under varying loads and interatomic spacings across different fretting directions. Synchronized variations in Δρ and potential energy difference ΔE are observed. Under constant fretting directions, the correlation coefficient k F N for ΔE and Δρ, and interatomic spacing Δz increase with load. When load varies, k F N shows an inverse trend relative to Δz under identical atomic spacing conditions, while their variation rates align. These findings provide an electron-level understanding of fretting mechanisms, offering a theoretical basis for designing durable, high-performance microelectronic devices.