Travail de fin d'études et stage[BR]- Travail de fin d'études : Study and design of a recycling process by magnetic separation of unmelted bimetallic powder from L-PBF[BR]- Stage d'insertion professionnelle

Abstract

Laser Powder Bed Fusion (LPBF) process allows powders of different materials to be selectively melted together. However, the unsintered powders are mixed together and therefore cannot be used anymore. To reduce waste, a method to separate powders presents a great interest. The goal of this thesis is to find and design a method to separate two powder mixes: 316L/CuCrZr and M300/CuCrZr. The difficulty lies in similar powder properties, such as density, particle size distribution and electrical resistivity. After discussion on different separation methods, the focus will be on magnetic separation process. For the 316L/CuCrZr couple, it appears that 316L shows a ferromagnetic behaviour only for smallest particles. This heterogeneous magnetic property makes a separation by magnetism difficult to achieve. On the other side, since M300 presents strong ferromagnetic behaviour, while CuCrZr a non-magnetic one, a magnetic-based separation is considered for this couple. A prototype is developed, based on free-fall separation and powered by an ultrasonic device. Some issues are raised and system parameters are discussed to find an optimal solution for the separation process.