• Journal of Welding and Joining
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• v.34 no.4
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• pp.17-22
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• 2016

In this study, we compared the physical and chemical properties evaluation for each size in the SUS316L metal powder produced by water atomization and gas atomization. and we analyzed the experimental data in order to find the basis of a suitable metal powder (SUS316L) for DED (Direct Energy Deposition) processing. Also it evaluated the properties of each layered surface and cross section according to the number of deposition and deposition speed. In the result of optical microscopy measurements, the metal powder by water atomization was the crack generated between the deposition layer, the deposition layer was poor quality. However, metal powder by gas atomization was obtained a relatively good deposition results than metal powder by water atomization.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2777-2781
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• 2008

Gas atomization of liquid metal using nozzle technology has more advantages over other methods. Previous study shows that high-velocity gas is important for effective liquid metal atomization. An important first step towards understanding the gas atomization using nozzle is complete evaluation of the flow fields. This will provide a basis for understanding how well high velocity gas is brought to bear on the liquid metal. Present work is a fundamental study of liquid metal atomization for various pressure ratio, different gas and temperature. A two-dimension, axisymmetry compressible Navier-Stokes equations are considered. Two-equation k-epsilon turbulence model is selected.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.8-9
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• 2006

Hybrid atomization is a new atomization technique that combines gas atomization with centrifugal atomization. This process can produce fine, spherical powders economically with a mean size of about 10 m diameter and a tight size distribution.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.6-7
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• 2006

Based on theoretical analysis, a new general equation of mean particle size applicable to both conventional atomization methods and new atomization processes is presented. In gas atomization, it is equivalent with and can be changed into Lubanska Equation. In centrifugal atomization, it can be changed into the equations that are currently the most widely used. In water atomization, it is similar to the equation proposed by Grandzol and Tallmadge. According to the universal equation, new correlations for mean particle size in novel atomization processes such as Hybrid Atomization and Multistage Atomization were proposed and agreed with our experimental data well.

• Journal of ILASS-Korea
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• v.11 no.2
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• pp.59-68
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• 2006

Experimental results of the metal powder production with internal mixing, internal impinging and the atomizer coupled with substrate design are presented in this paper. In a test with internal mixing atomizer, mean powder size was decreased from $37{\mu}m\;to\;23{\mu}m$ for Pb65Sn35 alloy as the gas-to-melt mass ratio was increased from 0.04 to 0.17. The particle size further reduces to $16.01{\mu}m$ as the orifice area is increased to $24mm^2$. The micrograph of the metal powder indicates that very fine and spherical metal powder has been produced by this process. In a test program using the internal impinging atomizers, the mean particle size of the metal powder was decreased from $22{\mu}m\;to\;12{\mu}m$ as the gas-to-melt-mass ratio increased from 0.05 to 0.22. The test results of an atomizer coupled with a substrate indicates that the deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in rum determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the subsrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as $3.13{\mu}m$ has been achieved, a level which is not achievable by the conventional gas atomization processes.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.12-13
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• 2006

The spherical and high quality Titanium fine powder "Tilop" has been produced with gas atomization furnace, Sumitomo Titanium Corporation originally designed. Recently, a new process which can produce Ti-alloy(Ti-6Al-4V) powders by utilizing our gas atomization process, of which raw material is sponge titanium pre-mixed with alloy chips or granules has been also developed. The particle size of gas atomized Ti-alloy powder and the mechanical properties of sintered Ti-alloy compacts prepared by metal injection molding were discussed in this study.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.477-478
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• 2006

Close-coupled atomizers are of great interest and controlling their performance parameters is critical for metal powder producing and spray forming industries. In this study, designed close-coupled nozzle systems were used to investigate the effect of the nozzle types and protrusion length of the melt delivery tube on the pressure formation at the melt delivery tube tip. The observed metal flow rate was not behaving as what was earlier assumed, namely that, deeper aspiration enhanced metal flow rate. Higher aspiration pressure at the tip of the melt delivery tube increases the stability of atomization process.

• Archives of Metallurgy and Materials
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• v.64 no.3
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• pp.917-920
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• 2019

Usually porous metals are known as relatively excellent characteristic such as large surface area, light, lower heat capacity, high toughness and permeability for exhaust gas filter, hydrogen reformer catalyst support. The Ni alloys have high corrosion resistance, heat resistance and chemical stability for high temperature applications. In this study, the Ni-based porous metals have been developed with Hastelloy powder by gas atomization and water atomization in order to find the effects of powder shape on porous metal. Each Hastelloy powder is pressed on disk shape of 2 mm thickness with 12 tons using uniaxial press machine. The specimens are sintered at various temperatures in high vacuum condition. The pore properties were evaluated using Porometer and microstructures were observed with SEM.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.4-5
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• 2006

An update and the latest results on molten metal atomization using a Pressure-Gas-Atomizer will be given. This atomizer combines a swirl-pressure atomizer, to generate a liquid hollow cone film and a gas atomizer to atomize the film and/or the fragments of the film. The paper is focused on powder production, but this atomization system is also applicable for deposition purposes. Different alloys (Sn, SnCu) were atomized to study the characteristics of the Pressure-Gas-Atomizer.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.16-17
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• 2006

In order to obtain spherical fine powder, we have developed a new method of high-pressure water atomization system using swirl water jet with the swirl angle $(\omega)$. The effect of nozzle apex angle $(\theta)$ upon the morphology of atomized powders was investigated. Molten copper was atomized by this method, with $\omega=0.2$ rad (swirl water jet) and $\omega=0$ rad (conical water jet). It was found that the median diameter $(D_{50})$ of atomized powders decreased with decreasing $(\theta)$ down to 0.35 rad in each $\omega$, but under ${\theta}<\;0.35$ rad, $D_{50}$ increased abruptly with decreasing $\theta$ for $\omega=0$ rad, while it was still decreased with decreasing $(\theta)$ for $\omega=0.2$ rad.