Abstract
No single lubricant can provide effective lubrication in various environments. In this study, both graphene (RGO) and WS2 were added to the Cu matrix to prepare self-lubricating composites that can adapt to different environments. Three kinds of Cu-based composites containing different volume ratios of lubricants were fabricated by a hot-pressing method. The physical and mechanical properties of the composites were measured. The tribological behaviors of the composites were tested using a ring-on-disc wear tester in air and vacuum environments. Scanning electron microscopy, 3D laser scanning confocal microscopy, and X-ray photoelectron spectroscopy were used to characterize the worn surface of the composites. Monolayer RGO was prepared, and the ID/IG ratio of RGO was 0.85. The fabricated composites were mainly a mechanical mixture of Cu/RGO/WS2. The total volume of lubricant was constant in the composites, and the hardness increased and thermal conductivity decreased with increasing volume ratio of WS2 to RGO. In air, Cu-RGO exhibited the lowest friction coefficient and wear rate, and Cu-WS2 showed the highest. In a vacuum, Cu-WS2 demonstrated the lowest friction coefficient and wear rate, whereas Cu-RGO was worn through. RGO played the lead role in wear reduction and self-lubrication in air, whereas WS2 was dominant in a vacuum. Cu-RGO-WS2 had greater potential applications due to its low sensitivity to different environments.