N. Emminghaus
S. Fritsch
H. Büttner
J. August
M. Tegtmeier
M. Huse
M. Lammers
C. Hoff
J. Hermsdorf
S. Kaierle

PBF-LB/M process under a silane-doped argon atmosphere: Preliminary studies and development of an innovative machine concept

Advances in Industrial and Manufacturing Engineering
Type: Zeitschriftenaufsatz (reviewed)
In laser-based powder bed fusion of metals (PBF-LB/M) the presence of oxygen is known to encourage embrit-tlement and impair the wetting properties of the substrate and solidified material. Conventionally, inert gases likeargon are used to reduce the residual oxygen content within the processing atmosphere. However, especially interms of reactive materials like titanium the remaining oxygen still causes critical oxidations.In this publication, a new approach for obtaining an oxygen-free processing atmosphere is presented. Therebythe argon shielding gas is doped with reactive monosilane to reduce the residual oxygen content to a rangecomparable to XHV (Extreme High Vacuum, thermodynamic oxygen activity1015). The handling of this newsilane-containing atmosphere requires the development of a special manufacturing system. Therefore, this workelucidates the development of an innovative machine system in accordance with the VDI (German Association ofEngineers) Guideline 2221. For determination and specification of the underlying requirements, the interaction ofthe gas mixture with various construction materials and Ti–6Al–4V powder material was investigated in a testchamber. It could be shown that metallic materials and smooth surfaces are favorable for the design whilepolymers are likely to degrade in silane-containing atmosphere. Further, the design of the gasflow in the buildchamber was optimized usingflow simulation. In order to avoid the deposition of reaction products in the processzone, a laminarflow should be established, which can be achieved by baffles and honeycomb structures.