A novel convergent–divergent annular nozzle design for close-coupled atomisation

ABSTRACT

Additive manufacturing processes such as selective laser melting and electron beam melting require small particle sizes. A widely used technique to produce suitable powders is close-coupled atomisation. To further decrease the achieved particle sizes, the annular geometry of the gas nozzle is changed to a convergent–divergent (CD) profile. This novel configuration is capable of operating stably at low pressures of 0.8 MPa and above. Beyond that, the unwanted effects of lick-back are avoided. Different nozzles with conventional and convergent–divergent annular geometry have been designed based on fluid-flow calculations. The aspiration pressure was measured to determine stable process windows. Powders from a CuSn alloy were produced using cold and hot gas atomisation to show the influence on the process stability, particle size and morphology. High-speed recordings are used to investigate the process conditions of the different nozzle configurations.

KEYWORDS:

• Atomisation
• melt
• close-coupled
• nozzle design
• CuSn
• powder
• convergent–divergent

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Daniel Schwenck http://orcid.org/0000-0002-2258-8779

Nils Ellendt http://orcid.org/0000-0001-7242-8063

Additional information

Funding

The authors thank the AiF and the BMWi for their financial support (Gefördert durch: Bundesministerium für Wirtschaft und Energie aufgrund eines Beschlusses des Deutschen Bundestages; Förderkennzeichen: KF2156512LL4).