A green approach to achieve extended lubricity of tribological systems: carbon nanoparticles as a case study

Purpose This review aims to conceptualize new or enhanced material systems with superior performance that contribute to extended service life and improved ecological compatibility of engineering components. Specifically, it presents a comprehensive summary of over a decade of research conducted at the Chair of Functional Materials (Saarland University, Germany), aligned with the principles of Green Tribology. The manuscript focuses on the development and evaluation of carbon nanoparticle-based coatings and composites, offering sustainable solutions to reduce friction and wear, and supporting the transition towards circular economy and eco-efficient design in tribological systems. Design/methodology/approach This study integrates green tribology principles with materials science to develop sustainable tribological systems using carbon nanoparticles (CNPs). It details the synthesis of CNP-reinforced metal matrix composites and coatings through optimized dispersion, powder metallurgy and electrophoretic deposition. Advanced surface texturing techniques, including laser patterning, are employed to enhance performance. The approach systematically evaluates the tribological behaviour under various surface conditions, focusing on friction, wear reduction and environmental impact, aligning with circular economy objectives. Findings The manuscript highlights that carbon nanoparticles – especially carbon nanotubes (CNT), carbon onions (CO), nanodiamonds (ND) and nanohorns (CNH) – significantly enhance the tribological performance of metal matrix composites and coatings. These materials reduce friction and wear, improve hardness, and extend component lifespan, particularly when combined with surface texturing techniques. Among the evaluated nanoparticles, CNTs showed the most effective self-lubrication, especially under dry and low-humidity conditions. The findings validate the potential of CNP-based systems as sustainable, high-performance solutions for engineering applications, demonstrating their alignment with green tribology principles and circular economy goals. Research limitations/implications While the manuscript offers a thorough summary of over a decade of focused research, it acknowledges that the field of green tribology and carbon nanoparticle-based materials is already well-established with extensive existing literature. As a result, the work does not aim to provide a comprehensive or exhaustive review of all advancements in the field. Instead, it presents a contextualized synthesis of the authors’ own contributions. This self-focus may limit the generalizability of findings and may not fully capture the breadth of global developments or alternative material systems beyond those explored at Saarland University. Originality/value This manuscript presents a comprehensive review of innovative research conducted at the Chair of Functional Materials (Saarland University), focusing on the development of carbon nanoparticle-based tribological systems aligned with green tribology and circular economy principles. It uniquely integrates solid lubricants such as CNTs, COs, ND and CNHs with surface texturing and sustainable processing to enhance durability and reduce environmental impact. Among these, CNTs showed superior self-lubrication and wear reduction. The work provides original insights into the design of high-performance, eco-efficient materials and offers valuable guidance for future research in sustainable tribological applications.