Powder properties and flowability measurements of tailored nanocomposites for powder bed fusion applications

A Lüddecke,O Pannitz,H Zetzener,J.T Sehrt,A Kwade

doi:10.1016/j.matdes.2021.109536

A Lüddecke, O Pannitz + Show 3 more

Open Access

https://doi.org/10.1016/j.matdes.2021.109536

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Abstract

The modification of metal alloy powders by coating with nanoparticles offers the possibility to improve additive manufacturing processes, in particular the powder bed fusion of metals with laser beams (PBF/LB-M), from the material side of view. Subsequently, component qualities including mechanical properties and microstructural characteristics could be improved. Furthermore, the modification enables improved energy utilization due to an increase in laser absorption. In this work three commercial additive manufacturing powders, namely stainless steel (1.4404), tool steel (1.2709), and aluminum alloy (3.2381) were coated with three different nanoparticles (Silicon carbide (SiC), few layer graphene (FLG), and iron oxide black (IOB) to increase the laser light absorption in the PBF/LB/M process, mechanical properties, and flowability of the powders. The coating was conducted within a fluidized bed system, resulting in homogeneous coatings. This study demonstrates, that well scalable processes i.e. stirred media milling and fluidized bed coating have the potential to improve the commercial AM powders regarding their bulk density, flowability, and energy absorption, which is a crucial step towards an improvement in the efficiency of the whole PBF process. Overall important information and relations were gathered to transfer them to the real powder deposition process in future work.

Highlights

Additive manufacturing processes (AM) of metals or polymers are progressively gaining interest in industrial applications and as well in the scientific community [1,2,3,4]
The results indicate that bulk densities can give first hints concerning the flowability of modified powders in relation to the feedstock powder, i.e. an assessment can be carried out whether a specific coating is suitable for PBF-LB/M
Ring shear test results show in first approximation the same tendencies at low executed normal stresses of 0.5, 1 and 3 Pa in comparison to the dynamic measurement results with the rotating drum

Summary

Introduction

Additive manufacturing processes (AM) of metals or polymers are progressively gaining interest in industrial applications and as well in the scientific community [1,2,3,4]. Multiple high energetic lasers and larger building envelopes have been implemented as a focal point in recent research to increase the productivity of the process [9,10]. This leads to extensive machine complexity and substantial prices. Another approach is to enhance the used powder material in order to improve the overall process. This is extensively done by adding nanoparticles to metal particles in order to build Metal Matrix Composites (MMC). Other research displayed higher tensile strengths and enhanced mechanical properties for graphene or rather Few Layer Graphene (FLG, defined as 2–10 layers of graphene [31]) enhanced metal powders [16,32,33,34,35]

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