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|Title:||Recycling of Ti6Al4V swarf into Powder feedstock for Additive Manufacturing: Towards Achieving Sustainable Development Goals|
|Supervisor:||Joshi, Ravinder Singh|
|Abstract:||The United Nations Development Programme (UNDP) listed responsible consumption and production as the 12th sustainable development goal. The efficient management of our shared natural resources and the way we dispose of toxic waste and pollutants are important targets to achieve this goal. Encouraging industries, businesses, and consumers to recycle and reduce waste is equally important as is supporting developing countries to move towards more sustainable patterns of consumption. One such waste originates from titanium (Ti) processing industries. Ti alloys especially Ti6Al4V (Ti64) have a variety of applications in the avionics and biomedical industry by virtue of their unique properties like high strength, lightweight, extraordinary corrosion resistance, and the ability to withstand extreme temperatures. In the quest to obtain various shapes and sizes of Ti64 components, predominately subtractive machining is employed which produces a significant volume of machining scrap in the form of swarf. Ti alloys being high-value materials, there is an urgent need to develop sustainable technologies to recycle the swarf. The high surface-to-weight ratio in addition to the presence of coolant, dust, and tool impurities makes conventional recycling of swarf economically unviable. The present study proposes multi-stage ball milling (BM) based sustainable technology to recycle Ti64 swarf into powder feedstock that can further be used as raw material for additive manufacturing (AM). Ti64 swarf was collected, cleaned, and ball-milled in an in-house designed and fabricated tumbler ball mill. In addition to bulk powder properties (flowability and spreadability) evaluation, the developed powder was characterised for particle size, morphology, hardness, and crystalline phases. Finally, the power was used as raw material for direct metal laser sintering (DMLS) to examine its suitability for AM. It was found that the 25 mm diameter balls resulted in the largest powder particle size change followed by 12.5 mm and 6.25 mm diameter balls. Near-spherical morphology of Ti64 powder particles having the size of 40-200 μm was obtained after 18 h of BM. The flowability and the spreadability analyses of the powder proved its suitability for utilization in AM process. Experiment results show that proper melting of the prepared powder takes place at 1000 mm/s scanning speed and 310 W laser power during the DMLS process. The sustainability of the proposed process was analysed using a comparative life cycle assessment (LCA). It was found that the proposed method consumed less energy (~ 59 %), has low eco-cost (~ 82 %), and has less GWP (~ 68 %) as compared to the GA and thus, has the potential to produce powders with regulated characteristics from Ti64 swarf.|
|Appears in Collections:||Masters Theses@MED|
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