Sustainable coating solutions: a comparative life cycle analysis of electrophoretic deposition and electroplating for graphene-reinforced anti-wear coatings

Graphene merges properties such as high conductivity and outstanding mechanical performance. In tribology, it is expected to be an excellent solid lubricant at both the macro-scale and micro-scale. As a result, graphene is particularly suitable for the self-lubricating anti-wear coatings production on metal substrates. Electrodeposition is one of the most effective processes and, therefore, most widely used in industries to produce metal-graphene coatings on conductive substrates. In particular, nickel-graphene electrodeposited coatings are the most present in literature. However, the environmental impact of the galvanic bath represents a limit in the widespread use of co-deposition through electroplating. The electrophoretic deposition may be an appealing alternative despite the solvent used for the graphene dispersion requires a high resource consumption, increasing the environmental impact. This paper investigates electrophoretic deposition and electroplating through life cycle assessment and costing procedures (LCA and LCC). To this aim, different coatings were produced considering many liquid mediums and tested to achieve specified performance. Then, ANOVA, life cycle assessment, and life cycle costing were performed to assess process repeatability and performance in terms of environmental impact. Electrophoretic deposition showed excellent results compared with electroplating, obtaining a maximum wear resistance improvement of over 80% and a significant reduction in environmental impact and cost in all the scenarios.