Sustainable recycling of waste metallic powder particles via cold spray additive manufacturing technology

This study proposes a sustainable and cost-effective approach for recycling high-value metallic waste generated during cold spray and grinding operations. Instead of discarding these by-products as industrial waste, a multi-stage process involving screening, segregation, and blending was employed to convert the recovered powders into functional feedstock for cold spray deposition. Three distinct layers (coatings) and two thick deposits (∼up to 7–8 mm) were developed on aluminium 6061 substrate using this recycled feedstock which includes SS316L, titanium, copper, and aluminium from cold spray and swarf particles from grinding waste. Microstructural characterization was done via scanning electron microscopy and energy dispersive spectroscopy, along with microhardness and scratch testing. The layers revealed the formation of dense microstructure with porosity below 2 % and a high Deposition Efficiency (D.E). Scratch-based wear testing demonstrated that all coatings exhibited significantly lower wear rates (up to an order of magnitude lower) compared to the substrate, with the Vacuum Waste 1 + Grinding Waste coating showing the highest wear resistance. These results confirm that recycled powders can produce coatings with superior mechanical and tribological performance to the base alloy. This work demonstrates the technical feasibility of valorising metallic overspray waste through cold spray technology, reducing the environmental footprint associated with waste disposal and raw material consumption. The results highlight the potential of cold spray to repurpose the waste and cleaner production technique that supports circular economy principles in the metalworking and surface engineering and additive manufacturing industries. • Sustainable recycling of cold spray and grinding metallic waste. • 70 %)Recycled powders yielded coatings with porosity <2 % & deposition efficiency ∼70 % • Thick (∼8 mm) deposits demonstrated full-scale parts building capability • Coatings showed enhanced wear resistance & lower CoF than Al-6061 substrate. • Reuse approach cut costs by ∼30 %, promoting circular economy and sustainable manufacturing