Effects of process parameters and cooling gas on powder formation during the plasma rotating electrode process

• Published in: Powder technology Vol. 393; pp. 301 - 311
• Main Authors: Cui, Yujie, Zhao, Yufan, Numata, Haruko, Yamanaka, Kenta, Bian, Huakang, Aoyagi, Kenta, Chiba, Akihiko
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-11-2021; Elsevier BV
• Subjects: Atmosphere; Cooling; Cooling effects; Electrodes; Experimental methods; Fabrication; Fluid flow; Gas flowing; Granulation; Helium; Numerical methods; Numerical simulation; Plasma rotating electrode process; Powder; Powder size; Process parameters; Rotating plasmas; Rotating speed; Rotation; Ti-6Al-4 V alloy; Numerical simulation; Plasma rotating electrode process; Ti-6Al-4 V alloy; Gas flowing; Powder size; Rotating speed
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2021.07.062

The plasma rotating electrode process (PREP) is rapidly becoming an important powder fabrication method in additive manufacturing. However, the low production rate of fine PREP powder limits the development of PREP. Herein, we investigated different factors affecting powder formation during PREP by combining experimental methods and numerical simulations. The limitation of increasing the rotation electrode speed in decreasing powder size is attributed to the increased probability of adjacent droplets recombining and the decreased tendency of granulation. The effects of additional Ar/He gas flowing on the rotational electrode on powder formation is determined through the cooling effect, the disturbance effect, and the inclined effect of the residual electrode end face simultaneously. A smaller-sized powder was obtained in the He atmosphere owing to the larger inclined angle of the residual electrode end face compared to the Ar atmosphere. Our research highlights the route for the fabrication of smaller-sized powders using PREP.
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•The limitation of increasing the rotational speed in decreasing powder size was clarified.•Cooling and disturbance effects varied with the gas flowing rate.•Inclined angle of the residual electrode end face affected powder formation.•Additional cooling gas flowing could be applied to control powder size.