• Journal of Powder Materials
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• v.24 no.6
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• pp.472-476
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• 2017

Porous W-10 wt% Ti alloys are prepared by freeze-drying a $WO_3-TiH_2$/camphene slurry, using a sintering process. X-ray diffraction analysis of the heat-treated powder in an argon atmosphere shows the $WO_3$ peak of the starting powder and reaction-phase peaks such as $WO_{2.9}$, $WO_2$, and $TiO_2$ peaks. In contrast, a powder mixture heated in a hydrogen atmosphere is composed of the W and TiW phases. The formation of reaction phases that are dependent on the atmosphere is explained by a thermodynamic consideration of the reduction behavior of $WO_3$ and the dehydrogenation reaction of $TiH_2$. To fabricate a porous W-Ti alloy, the camphene slurry is frozen at $-30^{\circ}C$, and pores are generated in the frozen specimens by the sublimation of camphene while drying in air. The green body is hydrogen-reduced and sintered at $1000^{\circ}C$ for 1 h. The sintered sample prepared by freeze-drying the camphene slurry shows large and aligned parallel pores in the camphene growth direction, and small pores in the internal walls of the large pores. The strut between large pores consists of very fine particles with partial necking between them.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.74-79
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• 2015

Wood powder is widely used in paperboard mills to increase bulk and reduce drying-energy consumption, but this material also deteriorates paper strength because it interferes with the bonds between fibers. Although there have been many studies done to improve the strength of paperboard containing wood powder, specific applications have not recently been observed in paperboard mills. In this study, we carried out a new approach for improving paperboard strength by developing a new organic filler with the ability to increase the bonds between fibers. The residue of tapioca starch was used as raw material to manufacture an organic filler. The functionalities, including bulk and strength, were evaluated by making handsheets containing either wood powder or tapioca organic filler, or a mixture of the two, and measuring their physical properties. The organic filler showed lower bulk improvement and higher paperboard strength than the wood powder. The mixture of tapioca organic filler and wood powder showed improved paperboard strength compared to wood powder alone. Therefore, tapioca residue can be used as a raw material to manufacture an organic filler for paperboard mills.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.121-128
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• 2010

This is to show some basic data for introducing both circulated aggregate and recycled powder producing waste concrete. Standard-mixing design for 24MPa has been basically used and added and replaced normal aggregate with recycled powder made of waste concrete. In addition, polycarboxylate high-range water reducing agent has been used because recycled powder is missing adhesive strength and it is not compare with cement's adhesive strength. Compressive strength with powder mixture of 2%, 4%, 6%, 8%, and 10% has been decreased down to 80% of normal concrete material strength without recycled powder mixture. $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ heated concrete were compressively tested in order to find out concrete strength resistant to high temperature. heat capacity was also tested, based on the expectancy of its low conductivity. In addition, thermal conduction test was tested in order to find out concrete insulation. According to this test, when concrete was tested by fire resistance, it using the circulation aggregate was same resulted by concrete using the natural aggregate. also, recycle powder was not effecting insulation performance. but it is fit to standard on concrete insulation of building law.

• Nuclear Engineering and Technology
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• v.30 no.2
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• pp.128-139
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• 1998

The effect of UO$_2$ powder property and oxygen potential on characteristics of sintered UO$_2$-Gd$_2$O$_3$ fuel pellets has been investigated. Two types of powder, mixture of AUC-UO$_2$ and Gd$_2$O$_3$powders (type I) and mixture of ADU-UO$_2$ and Gd$_2$O$_3$powders (type II), have been prepared, pressed, and sintered at 168$0^{\circ}C$ for 4 hours. Four sintering atmospheres with different mixing ratios of $CO_2$to H$_2$ gas ranging from 0 to 0.3 have been used. UO$_2$-Gd$_2$O$_3$ fuel has lower sintered density than UO$_2$ fuel, and the density drop is larger for powder type I than for powder type II. As the oxygen potential increases, the sintered density of UO$_2$-2wt% Gd$_2$O$_3$pellets increases but that of UO$_2$-10wt% Gd$_2$O$_3$ pellets decreases. It is found that pores are newly formed in UO$_2$-10wt% Gd$_2$O$_3$ pellets in accordance with the decrease in density. The grain size of UO$_2$-Gd$_2$O$_3$ fuel increases and a short range G4 distribution becomes homogeneous as the oxygen potential increases. A long range ed distribution and grain structure are inhomogeneous for powder type II. The lattice parameter of (U,Gd)O$_2$solid solution decreases linearly with Gd$_2$O$_3$ content. The dependence of UO$_2$-Gd$_2$O$_3$fuel characteristics on powder type and sintering atmosphere have been discussed.

• Journal of Powder Materials
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• v.31 no.2
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• pp.132-136
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• 2024

This study investigated the effects of revolution speed and ball size in planetary milling on the microstructure and dehydrogenation behavior of TiH₂ powder. The particle size analysis showed that the large particles present in the raw powder were effectively refined as the revolution speed increased, and when milled at 500 rpm, the median particle size was 1.47 ㎛. Milling with a mixture of balls of two or three sizes was more effective in refining the raw powder than milling with balls of a single size. A mixture of 3 mm and 5 mm diameter balls was the optimal condition for particle refinement, and the measured median particle size was 0.71 ㎛. The dependence of particle size on revolution speed and ball size was explained by changes in input energy and the number of contact points of the balls. In the milled powder, the endothermic peak measured using differential thermal analysis was observed at a relatively low temperature. This finding was interpreted as the activation of a dehydrogenation reaction, mainly due to the increase in the specific surface area and the concentration of lattice defects.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.04a
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• pp.21-21
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• 2004

• Journal of Magnetics
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• v.6 no.1
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• pp.13-18
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• 2001

Permalloy soft magnets have been produced by the powder injection molding process. Rheological characteristics of mixtures, debinding conditions, and the magnetic properties of permalloy after sintering have been investigated. A permalloy soft magnet with a permeability of 14200 could be obtained by preparing a mixture with a powder loading of 65.4 vol % and a PP/PEG binder systems solvent extraction, thermal debinding, and subsequent sintering at 1350$\^{C}$ in hydrogen. The permalloy soft magnet sintered in hydrogen had 95% of theoretical density and a magnetic induction of 13.2 kG in an applied magnetic field of 50 Oe.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.731-732
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• 2006

Recently warm compaction techniques are focused on and commercialization of one high-density compaction process in the P/M industry. Another development is a new SEGLESS using a developed lubricant that reduces ejection force at room temperature compaction. It is possible to achieve high-density by reducing lubricant amount. In this paper we confirmed that green density was $7.35g/cm^3$ at 686MPa of compaction pressure when the new SEGLESS was applied to relatively lower temperature warm compaction process, such as $80^{\circ}C$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.87-87
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• 2003

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.217-227
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• 2000

The permalloy soft magnet was produced by powder injection molding process. Rheological characteristics of mixtures, debinding conditions and the magnetic properties of permalloy after sintering ware investigated. The permalloy soft magnet with a permeability of 14200 could be obtained by preparing a mixture with a powder loading of 65.4 vol.% and PP/PEG binder system, solvent extraction, thermal debinding and subsequent sintering at 1350 $^{\circ}C$ in hydrogen. The permalloy soft magnet sintered in hydrogen showed a 95 % of theoretical density and a magnetic induction of 13.2 kG at the applied magnetic field of 50 Oe