The European plan for the transition to a circular economy (CE) has the goal of rethinking resource efficiency and materials flows, offering a life-cycle view and being the sustainable design of products in the production sector one of the key points in the proper implementation of CE [1]. However, the current practices related to its implementation are mainly focused from the end-of-life perspective, especially the development and optimization of recycling processes. The Eco-Design Directive[2] includes the implementation of strategies such as selection of low impact materials, reduction of materials usage, optimization of production techniques, reducing the impact during use, and optimization of initial lifetime, among others. Those strategies enforce the principles advocated by Cooper of durability and optimized energy and material consumption [3].
Proper material selection is a prerequisite for the eco-design of products and is directly related to the design strategies for slowing and closing the loop in a CE context. Slow the loop strategies include slowing material flows in each phase of the life cycle such as, design for durability and product life extension. In this context, materials science acts as a crucial link between different eco-design strategies, since it can provide the necessary knowledge and material’s technology for the proper material’s selection for the design and production of engineering components with an extended service life. This will consequently result in the reduction of material demand and energy consumption.
Energy loss due to friction and wear (i.e., tribological contacts) were estimated to be larger than 20% of the global energy consumption [4]. They could potentially be reduced by about 40% as result of new materials, improved surfaces, and better lubrication technologies [4]. In the last two decades, a new tribology subdiscipline (Green Tribology) has been developed which supports the preservation of resources, energy, and material criticality [5,6].
This work has the objective of conceptualizing new or enhanced materials with improved performance that will result in products and components with an extended service life and improved ecological compatibility. In particular, the development of material systems with reduced friction and wear that positively influence the decision making during product and component design. Based on that, the current work highlights promising results obtained on the use of carbon nanoparticles (e.g., carbon nanotubes, carbon onions, nanodiamonds, etc.) as the main component in the fabrication of protective and low-friction coatings, and metal matrix composites (MMC) with self-lubricating  characteristics [7–10]. Furthermore, the combination of a chemistry-free process (laser interference patterning) with carbon-nanotube coatings showed a three-fold friction reduction in comparison to a benchmark (untextured/uncoated) system [11]. Finally, improved self-lubricating effects are obtained by combining self-lubricating MMC with an optimized solid-lubricant coating and a periodically-structured surface, resulting in a system with 4-fold reduced coefficient of friction and 115-fold wear reduction compared to a reference state.


1    E. Commission, COM(2015) 614 final
2    E. Commission, Directive 2009/125/EC.
3    A. Mestre and T. Cooper: Des. J., 2017, vol. 20, pp. S1620–35.
4    K. Holmberg and A. Erdemir: Friction, 2017, vol. 5, pp. 263–84.
5    S. Zhang: Friction, 2013, vol. 1, pp. 186–94.
6    M. Freschi, A. Paniz, E. Cerqueni, G. Colella, and G. Dotelli: Lubricants, DOI:10.3390/lubricants10060129.
7    L. Reinert, M. Zeiger, S. Suárez, V. Presser, and F. Mücklich: RSC Adv., 2015, vol. 5, pp. 95149–59.
8    L. Reinert, M. Varenberg, F. Mücklich, and S. Suárez: Wear, 2018, vol. 406–407, pp. 33–42.
9    L. Reinert, S. Suárez, and A. Rosenkranz: Lubricants, DOI:10.3390/lubricants4020011.
10    S. Suárez, A. Rosenkranz, C. Gachot, and F. Mücklich: Carbon N. Y., 2014, vol. 66, pp. 164–71.
11    L. Reinert, F. Lasserre, C. Gachot, P. Grützmacher, T. Maclucas, N. Souza, F. Mücklich, and S. Suarez: Sci. Rep., 2017, vol. 7, pp. 1–13.