• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.99-100
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• 2012

• Journal of Powder Materials
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• v.10 no.5
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• pp.310-317
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• 2003

Two-component ceramic (alumina-zirconia) composites were fabricated by a soft-solution process in which polyethylene glycol (PEG) was used as a polymeric carrier. Metal salts and PEG were dissolved in ethyl alcohol without any precipitation in 1:1 volume ratio of alumina and zirconia. In the non-aqueous system, the flammable solvent made explosive, exothermic reaction during drying process. The reaction resulted in formation of volume expanded, porous precursor powders by a vigorous decomposition of organic components in the precursor sol. The PEG content affected the grain size of sintered composites as well as the morphology of precursor powders. The difference of microstructure in sintered composite was attribute to the solubility and homogeneity of metal cations in precursor sol. At the optimum amount of the PEG polymer, the metal ions were dispersed effectively in solution and a homogeneous polymeric network was formed. It made less agglomerated particles in the precursor sol and affected on uniform grain size in sintered composite.

• The Korean Journal of Ceramics
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• v.5 no.1
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• pp.73-77
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• 1999

Capsule free hot isostatic pressing (HIPing) of 12 mol% $CeO_2-88 mo% ZrO_2 (12CeO_2-88ZrO_2)$ powder was conducted at 1100~$1200^{\circ}C$ using the powder crystallized in supercritical methanol followed by supercritical drying. Porous $12CeO_2-88ZrO_2$ ceramics with ~35% open porosity, micropore diameter of ~23 nm and a narrow pore size distribution were fabricated by capsule free hot isostatic pressing at $1100^{\circ}C$. The porosity increased with decrease in HIPing temperature and was accompanied by a steady decrease in fracture strength.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.467-471
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• 2018

Diatomite powder, a naturally occurring porous raw material, was used to make ceramic materials with porosity and high strength. The sintering behavior of the diatomite powder at various sintering temperatures suggests that diatomite monoliths with a high porosity and strength can be prepared at $1100^{\circ}C$. The compressive strength of the sintered diatomite monoliths increased as the sintering temperature increased, and the molding pressure of 2 MPa and the binder of 18.6 wt.% were excellent. When the sintering temperature rises, the diatomite powder is melted, and its pores gradually disappear. SEM images show that strengthening begins with the formation of inter-particle bonds at a low sintering temperature.

• Journal of Powder Materials
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• v.28 no.4
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• pp.331-335
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• 2021

The effects of drying temperature on the microstructure of porous W fabricated by the freeze-casting process of tert-butyl alcohol slurry with WO₃ powder was investigated. Green bodies were hydrogen-reduced at 800℃ for 1 h and sintered at 1000℃ for 6 h. X-ray diffraction analysis revealed that WO₃ powders were completely converted to W without any reaction phases by hydrogen reduction. The sintered body showed pores aligned in the direction of tert-butyl alcohol growth, and the porosity and pore size decreased as the amount of WO₃ increased from 5 to 10vol%. As the drying temperature of the frozen body increased from -25℃ to -10℃, the pore size and thickness of the struts increased. The change in microstructural characteristics based on the amount of powder added and the drying temperature was explained by the growth behavior of the freezing agent and the degree of rearrangement of the solid powder during the solidification of the slurry.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.447-450
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• 1997

Temperature distribution measurements in the mockup apparatus of reactor vessel were performed to determine the effective thermal conductivity of Al powder porous media where stainless steel tubes were installed with different geometry. The temperature distributions at four separated sections with different arrangements of porous media have different slopes according to the geometrical configuration. From the measured temperature distribution, effective thermal conductivity have been derived using the least square fitting method.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.529-533
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• 2010

Porous frit-bonded alumina ceramics were fabricated using alumina and frit as raw materials. The effects of frit content and sintering temperature on microstructure, porosity, and flexural strength were investigated at low temperature of $750{\sim}850^{\circ}C$. Increased addition of frit content or higher sintering temperature resulted in improved flexural strength of porous frit-bonded alumina ceramics. It was possible to produce frit-bonded alumina ceramics with porosities ranging from 35% to 40%. A maximum strength of 52MPa was obtained at a porosity of ~38% when 90 wt% alumina and 10 wt% frit powders were used.

• Journal of Powder Materials
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• v.9 no.1
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• pp.50-60
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• 2002

SPS(Spark Plasma Sintering ) is known to be an excellent sintering method for porous materials. In the present work an attempt has been made of fabricating porous 316L Stainless steel with good mechanical properties by using controlled SPS process Porosity was 21%~53% at sintering temperature of $600^{\circ}C$~100$0^{\circ}C$ The limit of porosity with available mechanical strength was 30% at given experimental conditions. Porosity can be controlled by manipulating the intial height of the compact by means of the supporter and punch length. The applied pressure can be exerted entirely upon the supporter, giving no influence on the specimen. The specimen is then able to be sintered pressurelessly. In this case porosity could be controlled from 38 to 45% with good mechanical strength at sintering temperature of 90$0^{\circ}C$. As the holding time increased, neck between the particles grew progressively, but shrinkage of the specimen did not occur, implying that the porosity remained constant during the whole sintering process.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.338-342
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• 2007

Porous silicon nitride ceramics were prepared by SHS (Self-Propagating High Temperature Synthesis) from silicon powder, silicon nitride powder and pore-forming precursor. The microstructure, porosity and the flexural strength of the porous silicon nitride ceramics were varied according to the Si/Si3N4 ratio, size and amount of the pore-forming precursors. Some sample exhibited as high flexural strength as $162{\pm}24\;MPa$. The high strength is considered to result from the fine pore size and the strong bonding amoung the silicon nitride particles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.1026-1029
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• 2002

Outlet of gas has been a big problem in deforming rubber or plastic in pressing mold. Air vent has been used to solve the problem, but it has weak points such as the increased cost, the increased number of process, and vent marks on the surface of a produce. In this study, the sintering method is used for making porous metal mold. Porous metal mold has many open pores, which are very small. When Porous metal mold is used for pressing mold, all process would be made short, produce cost would be down, and it would not leave vent marks on the surface of a produce. Porosity varies from sintering and pressing conditions, which are the pressure of compacting powder, the length of sintering time, sintering temperature and sintering atmosphere etc. This study will find optimized sintering temperature condition for the Porous metal mold.