In situ formation of carbon-based tribo-films via engineered composite design for enhanced anti-adhesion performance in metallic contacts

Metallic contacts frequently experience severe adhesion and accelerated wear, potentially leading to catastrophic system failure. This challenge is especially pronounced for Cu-Al sliding pairs employed in electromagnetic launch systems and electrical equipment, where conventional protective measures, such as surface hardening or external lubrication, have proven insufficient. In this study, we introduce a novel Cu-W-graphene nanoplatelets (GNPs) composite coating on Cu alloy substrates designed to effectively mitigate adhesive wear against Al counterfaces. The coating strategically incorporates GNPs within a Cu-W matrix, forming a self-sustaining anti-adhesion mechanism during dry sliding conditions against 7075 Al alloy. Exfoliated GNPs dynamically transform into a stable amorphous carbon tribo-film approximately 20 nm thick at the sliding interface. Compared to uncoated Cu alloy and standard Cu-W coatings, the Cu-W-GNPs composite coating decreased the friction coefficient to 0.19, restricted the Al adhesion area to 3.05 %, and reduced the adhesion film thickness to 0.39 μm. Microstructural analyses combined with first-principles density functional theory calculations verified that the in situ-formed carbon film effectively suppressed Cu-Al metallurgical bonding, reducing the interfacial adhesion energy from 2.46 J/m² (Cu-Al) to 0.74 J/m² (C-Al) through the inhibition of metallic bonding and electron transfer at the atomic level. These findings demonstrate a robust and promising approach for enhancing metallic contact durability via engineered composite coatings capable of generating protective tribo-films in situ, thereby providing significant potential for diverse engineering applications requiring reliable and robust metal-on-metal sliding interfaces.