New Approach in Spherical Powder Production with Laser
Chivel Y
Published on: 2025-11-01
Abstract
A process of laser gas atomization has been developed to obtain a spherical metal powder with a particle size of 30-100 μm using laser beams of conical geometry.
A process is presented for obtaining a spherical powder in a wide size range of 50 nm - 100 μm, in which a continuous near-surface optical discharge with a temperature of 20 kK is formed using conical laser beams in an inert gas flow, into which the material is introduced in the form of a wire or a powder flow. Particle condensation is strongly and rapidly quenched by the inert gas flow, resulting in high super saturation. The efficiency of the proposed laser method for producing powders is up to 0.5 kg/kWh at an electric power of 16 kW, while the existing, most efficient methods of plasma and gas spraying provide an efficiency of no better than 0.1-0.25 kg/h kW. The method can be used to obtain powders from various materials - metals, ceramics, plastics, and suspensions.
The process of formation of nanoparticles by means of inert gaseous condensation of metal vapors obtained by laser evaporation of a micro powder flow of 40–60 μm with a particle concentration of 104–106 cm–3 has been studied. The resulting nanoparticles with a size of 20-50 nm are collected in the form of conglomerates up to 100 nm in size. The productivity of the process reaches 0.2 kg/kWh.
Keywords
Atomization; Melting; Optical discharge; Laser evaporation; Gas-phase condensation; ParticlesIntroduction
There is a known method and a device that implements it for obtaining nanopowders by evaporating the target with a laser beam and subsequent condensation of the vapor of the target material in a gas flow. As the process is carried out in the evaporation mode, the process productivity does not exceed 100 g/h at energy costs of 40 Wh/g. There are numerous works on the preparation of nanoparticles in a liquid by laser ablation. But their effectiveness is extremely low.
The most productive at present are the methods of gas and plasma atomization.
During gas atomization, supersonic gas jets spray a jet of molten metal. The range of sizes of the obtained particles is -30-200 microns. But the very high costs of melting a large mass of metal under 100 kW of power and the efficiency of the process (4 kWh/kg).
Plasma atomization seems to be the technology providing the best yield of quality powders within the range of 30-200 microns.
The plasma atomization family of processes remains very inefficient energetically. For example, a typical plasma atomizer [1] could use 3 plasma torches set at a power of 45 kW each and a preheat source of 8 kW to atomize a Ti-6AI-4V wire at a rate of 5 kg/h. This represents 143 kW of raw power to treat 5 kg/h, which translates into a specific thermal power input of 28.6 kWh/kg. This represents more than 82 times the theoretical specific thermal power input requirement (0.347 kWh/kg).
In addition, these processes do not allow obtaining nanosized particles.
It would thus be desirable to provide a novel apparatus and process for producing spherical powders in a wide range of particle sizes from nano to 100 microns at a large industrial scale.
New Approach In Powder Production
Laser Gas Atomization
The main reason for the low efficiency of industrial powder production processes is the low concentration of the energy flow. During plasma atomization, the diameter of the sprayed wire is 3 mm, and the diameter of the plasma flows is 20 mm. With gas atomization, a large amount of metal is melted inefficiently. A new approach has been developed to the process of obtaining powders using a highly concentrated energy source—a laser—and special optical schemes using conical laser beams. Also applied is a unique physical object—an optical discharge.
The developed optical system is shown in Fig. 1.
In this system, the wire is introduced into the focal region of a single conical beam or the focal region of a system of several beams arranged around the perimeter. The end of the wire is heated to melting and sprayed with supersonic jets of inert gas—it is atomized.
Figure 1: System for Laser Gas Atomization.
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