34 - Effect of the debinding/sintering strategy on the densification of aluminium alloys processed through Material Extrusion (MEX) Additive Manufacturing
Abstract
Although powder bed fusion is the most widespread technique for additive manufacturing of metal parts, sintering assisted techniques have shown a growing interest in recent years. These techniques, such as binder jetting, stereolithography or direct-ink writing can be attractive as they generally involve cheaper printing machines, but also because they are more in-line with the controlled industrial processes in Powder Metallurgy. Indeed, the 3D parts are printed in their green state and must further undergo a debinding and sintering treatment to reach their final properties. Among these processes, Material Extrusion (MEX) Additive Manufacturing, which relies on the use of Metal Injection Molding (MIM) feedstock, benefits from the passed development of MIM industry. In this technique, MIM granules are extruded through the heated nozzle of a printer to build the part. The powder-polymer granules being optimized for powder forming, it makes it possible to efficiently crush the filament during printed, allowing to reach green density of the metal in the printed part as high as 60%. The further debinding and sintering treatments are basically the ones specified for MIM parts, meaning that industrial companies in the sector can easily transpose their knowledge from MIM to MEX to diversify their applications. However, they are remaining challenges depending on the material to be printed. The pressure-less sintering step might be an issue for material with a native oxide layer that hinder the diffusion required for sintering, as it is the case for aluminium alloys. In this work, we investigate the feasibility of this process for the 6061 aluminium alloy. As the use of a nitrogen atmosphere can be beneficial for aluminium sintering according to the literature, the effect of both debinding and sintering atmosphere on the reached density and final microstructure was studied. In addition, the benefit from using an oxygen getter as well as the effect of both sample size and furnace filling ratio (in volume) were investigated with the aim of proposing a strategy that maximizes densification.
Speaker
Marion Coffigniez
Discover speaker profileUniversité Grenoble Alpes, Saint-Martin d'Hères, France
Conference
34 - Effect of the debinding/sintering strategy on the densification of aluminium alloys processed through Material Extrusion (MEX) Additive Manufacturing
Date/Time
20/03/2024
5:00 pm -5:20 pm
Location
Room 7