Key Insights into Silver Matrix Nanocomposites Reinforced with Solid Lubricants for Electrical Contacts: A Review

Metal-based electrical contact materials (ECMs) are essential in switching devices and rotating electrical machines, where sliding contacts enable reliable current transmission under motion. These materials must exhibit high conductivity, low friction, and wear resistance to meet industrial demands. However, their reliability is limited by wear, oxidation, arcing, and other failure mechanisms that increase contact resistance and degrade performance. To address these issues, researchers have developed self-lubricating metal matrix composites (MMCs), particularly copper (Cu) and silver (Ag)-based composites reinforced with solid lubricants such as molybdenum disulfide, tungsten disulfide, graphite, carbon nanotubes, graphene, and its derivatives. While Cu and Ag provide excellent conductivity, each has trade-offs in cost, oxidation resistance, and mechanical strength. Strategies for improving reliability involve material optimization, surface treatments, lubrication, contact design modifications, and advanced manufacturing. Although MMCs are widely reviewed, self-lubricating Ag matrix nanocomposites (AgMNCs) for sliding contacts are underexplored. This review highlights recent progress in AgMNCs produced by conventional or modern powder metallurgy techniques, focusing on the role of solid lubricants, testing conditions, and microstructure on tribological performance. Wear mechanisms, research gaps, and future directions are discussed, highlighting pathways toward the development of reliable sliding contacts.