Addressing safety and sustainability issues in the development of nano-enabled MULTI-FUNctional materials for metal additive manufacturing

This paper presents a comprehensive investigation into the sustainable development of nano-enabled multifunctional materials (NMMs) for metal additive manufacturing (MAM), based on the principles of the Safe and Sustainable-by-Design (SSbD) framework. The work focuses on both environmental impacts and health risks potentially associated with these materials, offering a groundwork for a more complete SSbD assessment that includes socio-economic considerations. The Life Cycle Assessment (LCA) identified significant environmental advantages of using Titanium Nitride (TiN) and Chromium Nitride (CrN) in wire coating processes over Titanium Carbide (TiC), with a 77% reduction in environmental impacts. However, despite the emphasis on environmental aspects during materials selection, the primary environmental hotspot is the heat treatment stage used during the process to shape NMMs into pellets. Eco-toxicity assessments performed on both nano- and microparticles from the studied NMMs for MAM, identified specific thresholds to ensure over 80% cell viability, labelling MoCu and CCuCr as particularly cytotoxic. Additionally, a task-based risk assessment in laboratory environments, evaluating the potential release of engineered nanoparticles (ENPs), identified minimal inhalation exposure risk for workers due to effective control measures implemented. Overall, by integrating findings on eco-toxicity, worker safety, and environmental hotspots in production processes, this study offers an approach for advancing sustainable practices during the production of NMMs for MAM in laboratory settings. These findings can be valuable for future research and development in the field, ensuring that sustainability and safety are integral to the advancement of nanotechnology.