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2 2025

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Features of the process of formation and dispersion of a liquid layer and formation of powder particles in plasma-arc atomization of current-conducting solid and flux-cored wire

Gao Shiyi, Kryvtsun Ihor, Korzhyk Volodymyr, Strohonov Dmytro, Burlachenko Oleksii, Demіanov Oleksii, Tereshchenko Oleksii

Advances in Science and Technology. Research Journal

2025

Vol. 19, no. 5

58--72

The paper gives the results of mathematical modeling and experimental studies of the processes of formation and fragmentation of the liquid layer and formation of powder particles in plasma-arc atomization of current-conducting solid stainless steel AISI 316L wire and flux-cored Fe-Al wire. Mathematical modeling showed that initial fragments of size d0 = 670–780 μm form at plasma-arc atomization of the above-mentioned wires, where after their separation from the tip of the atomized wire their multiple disintegration in the plasma jet takes place, which ends at the distance of ~ 120 mm with formation of fine spherical fragments (powders) with the average diameter of 105–125 μm. Experimental studies on determination of the initial size of the drops, forming at metal drop separation from the liquid layer, using high-speed filming, showed that their size is d0 = 720–815 μm, and size of atomization products (powder) determined using the sieve analysis method are equal to 119–142 μm. Comparison of the obtained experimental and calculated data showed that that for atomization of both the solid stainless steel AISI 316L wire and flux-cored wire of Fe-Al system the main fraction of powder particles is 1–300 μm, which makes up 96–99 wt. % in both the cases, the error between the theoretical and experimental data being not higher than 7–32 %, depending on powder fraction, allowing application of the mentioned mathematical complex model to determine the optimal modes of plasma-arc atomization process with a wide range of wire materials. The study of the shape parameters and structure of AISI 316L and Fe-Al powders showed that most of the particles have a regular spherical shape with a sphericity coefficient close to 0.8–0.9, the microstructure of which is characterized by the absence of pores and voids.

Evaluation of the possibility of obtaining spherical powders of titanium alloy Ti 6Al 4V by supersonic reverse polarity plasma torch for use in additive manufacturing

Gao Shiyi, Korzhyk Volodymyr, Strohonov Dmytro, Tereshchenko Oleksii, Demіanov Oleksii, Ganushchak Oleg

Advances in Science and Technology. Research Journal

2025

Vol. 19, no. 8

434--448

This work demonstrates the possibility of producing spherical Ti-6Al-4V Grade 5 alloy powders with superior technological properties compared to those obtained through conventional industrial gas atomization methods for additive manufacturing, by utilizing plasma atomization of a 1.0 mm diameter solid wire. The process employs supersonic plasma jets generated by a DC reverse polarity plasma torch with vortex arc stabilization. The plasma torch has a copper hollow electrode anode and a special diffusive nozzle cathode. Analysis of the particle size distribution of the powder showed the main fraction of -140 μm 96 %wt., and the amount of the finely divided fraction of -63 μm is up to 55-60 %wt. Also, using subsonic jet had been give fraction -250 μm, which is 97 %wt., and the amount of the finely-divided fraction -63 μm does not exceed 30 %wt. The study of the shape and structure properties of Ti 6Al 4V Grade 5 powder showed that the sphericity coefficient reaches up to 0.9, the number of defects in the form of satellites and irregular particles does not exceed 1 %wt. In terms of technological characteristics, Ti 6Al 4V Grade 5 powder obtained by the adopted technique is on par with the industrial method of producing spherical powders for additive manufactuing by the direct polarity plasma torches.