The automotive sector is demanding higher specifications to achieve maximum efficiency; in this sense a new generation of lubricants with higher thermo-oxidative stability and superior tribological properties is being explored. The formulation of nanolubricants based on the nature of different nanomaterials is one of the most recent approaches, with several gaps to cover, such as dispersion stability, related to the compatibility of proposed nanomaterials with conventional additives and baseoils used in lubricant formulation. This study evaluated the effect of ZnO nanomaterial dispersed in a commercial engine oil using two different approaches; the use of surfactant and nanomaterial surface functionalization to promote higher stability and lower cluster size. Experimental evidence shows a synergetic effect between the tribological protection mechanism and the antioxidant properties in the lubricant. The effect of nanoparticle cluster size, functionalization level, and nanomaterial content are presented.

The objective of this paper is to highlight the need to combine lifecycle environmental assessment with durability evaluation (tribology and engine tests) to evaluate the potential of surface technologies to contribute to the green deal, in order to make Europe the first climate-neutral continent. Tribology is a scientific discipline that allows one to understand the system reaction to friction and wear. Tribological testing machines are prepared to measure friction at the laboratory level to minimize the wear and heat dissipation of two bodies in relative movement, thus improving the energy efficiency and minimizing CO₂ emissions. In this paper, different surface technologies, such as high-velocity oxyfuel (HVOF), physical vapor deposition (PVD), and clean Cr electrolytic processes, are analyzed as promising surface technology solutions from both performance and environmental impact perspectives to replace harmful Cr(VI) coatings. The tribology simulates the working conditions of the real system at the laboratory level, reproducing the failure mechanism and facilitating the laboratory screening of the energy efficiency and durability of materials solutions for certain tribological systems—in this case, engine components. The tribological test results give information about the behavior of materials, while the engine tests gives information about the behavior of components. In this paper, the environmental impact of the production process of the coatings is also analyzed. Two hard chrome processes are compared, demonstrating that by controlling the production process it is possible to significantly reduce the environmental impact of the chrome-plated process, minimizing the environmental impact to that of PVD coatings. The environmental impact of the tested HVOF process is lower than traditional Cr(VI)-plated coatings but higher than PVD coatings. Combining the information from the lifecycle assessment (LCA) and tribological studies, it is possible to assess both the performance and the environmental impact of the surface treatments. This methodology is a tool to that can be used minimize CO₂ emissions at the design phase to improve the energy efficiency of products and processes.