- [Korean]
- Preparation of Porous W-Cu by Freeze Casting of Tert-butyl Alcohol Slurry Mixed with WO3-CuO Powder
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Youngmin Kim, Ji Young Kim, Minju Son, Wonyong Kwon, Eui Seon Lee, Sung-Tag Oh
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J Powder Mater. 2025;32(6):466-471. Published online December 31, 2025
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DOI: https://doi.org/10.4150/jpm.2025.00437
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 Abstract
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- The influence of process conditions on the microstructure of porous W-Cu, fabricated by freeze casting using tert-butyl alcohol as the freezing agent, was investigated. The slurries containing 10 vol% of WO3-CuO powder were prepared by milling with a small amount of citric acid and polyethylene glycol as dispersants. The slurries with dispersion stability were frozen in a mold with the lower part cooled to -25°C, followed by sublimation in a vacuum to remove the freezing agent. The sintered W-1 vol% Cu in a hydrogen atmosphere exhibited aligned pores with the size of 50 μm, which were generated by sublimation of directionally solidified tert-butyl alcohol crystals. In the cross-section of the specimen, hexagonal pores corresponding to the crystal structure of tert-butyl alcohol was observed. Microstructure analysis of the struts revealed that Cu was distributed non-uniformly due to the mutual insolubility and low wettability of the W-Cu system.
- [Korean]
- Effect of Powder Preparation Method on the Microstructural Characteristics of Sintered W-7Ni-3Cu Heavy Alloy
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Youngmin Kim, Ji Young Kim, Minju Son, Wonyong Kwon, Eui Seon Lee, Sung-Tag Oh
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Received February 13, 2026 Accepted April 16, 2026 Published online April 21, 2026
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DOI: https://doi.org/10.4150/jpm.2026.00038
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Abstract
- The effect of powder characteristics and sintering temperature on the properties of W-7Ni-3Cu is investigated. The heavy alloy powders were prepared by ball milling and hydrogen reduction of elemental metal or metal oxide powders. Microstructural analysis revealed that the powder mixtures reduced by hydrogen at 800oC consist of a trace amount of Ni4W phase along with the metal W phase and Ni-Cu solid solution. Additionally, compared to metal powder, the powder mixture using oxide as raw material exhibited a relatively fine particle size. The W-7Ni-3Cu alloys sintered using oxide powders had relative density of over 99%, whereas the specimens using metal powders as a raw material showed relatively low values of 87.8~98.2%. The Vickers hardness of the sintered specimens using oxide powder was 3.34–3.92 GPa, which was higher than that of 2.39–3.22 GPa measured when using metal powders. The observed results can be attributed to the relatively high density and the reduced grain size.
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