• Proceedings of the Korea Association of Crystal Growth Conference
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• 2000.06a
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• pp.151-163
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• 2000

A polymerized organic-inorganic complexation route is introduced for the synthesis of oxide ceramic powders. Polyvinyl alcohol was used as the organic carrier for precursor ceramic gel. Porous and soft powders, which have a high specific surface area, were obtained after calcinating the aerated precursors. The PVA content and its degree of polymerization had a significant influence on the homogeneity of the final powder. In particular, attrition milling process with the porous powder resulted in ultra-fine particles. In the case of the preparation of cordierite powder, nano-size powder, which has a high specific surface area of 181 ㎡/g, was obtained by the milling process. The complexation route was also applied to the synthesis of unstable phase in room temperature like beta-cristobalite, high temperature form of silica.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.110-116
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• 2003

We have developed a high performance powder, which has a quenching efficacy not only for short-chain fatty acids and amines, but also for vinyl ketones (l-octen-3-one, cis-l,5-octadien-3-one), newly found as other key compounds in axillary malodor. By investigating various powders known to have a quenching efficacy, we finally developed a highly porous silica bead containing magnesium oxide. We found that the superior deodorant effect performed by this powder was the result of multiple effects due to both an excellent physical adsorption capability from its high porosity and a specific adsorption of vinyl ketones by magnesium in the powder. An antiperspirant formulation containing both this powder and a Morus alba extract showed good efficacy as a deodorant.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1115-1122
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• 1993

Several yield criteria for porous materials are compared with each other, defining the apparent yield stress as the yield stress of the porous material in simple compression. It was found that the plastic Poisson's ratio is the parameter needed to define the yield criterion, rather than the relative density. The plastic Poisson's ratio is regarded as a material characteristic that is obtained from a simple compression test. A new form of yield criterion was suggested, and it was applied to hydrostatic compression as well as uniaxial strain compression of sintered Al-2024 powder. The crossover point in the mean stress vs volume change curves of the processes was predicted. It is presented that the flow stress of the fully densed material can be obtained from that of the porous material using relations obtained from the yield criterion.

• Journal of Powder Materials
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• v.21 no.5
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• pp.389-398
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• 2014

Macroporous ceramics with tailored pore size and shape could be used for well-established and emerging applications, such as molten metal filtration, biomaterial, catalysis, thermal insulation, hot gas filtration and diesel particulate filters. In these applications, unique properties of porous materials were required which could be achieved through the incorporation of macro-pores into ceramics. In this article, we reviewed the main processing techniques which can be used for the fabrication of macroporous ceramics with tailored microstructure. Partial sintering, replica templates, sacrificial fugutives, and direct foaming techniques was described here and compared in terms of microstructures and mechanical properties that could be achieved. The main focus was given to the direct foaming technique which was simple and versatile approach that allowed the fabrication of macro-porous ceramics with tailored features and properties.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.59-63
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• 2004

In recent days. it is necessary to find environment-friendly way of diposing industrial waste and reclying system. So this study will analyze the property of Porous concrete improved by concrete waste powder and recycled lightweight aggregate and then suggest the ways of reclying. The method deals with experimenting unit weight of capacity. thermal conductivity, compression and ultrasonic pluse velocity. Considering the relation between ultrasonic pluse velocity and unit weight & thermal conductivity through the graph. the result of relation between ultrasonic pluse velocity and unit weight & thermal conductivity on the graph expessed their high interaction shown as direct proportion on the graph. Recycled Porous concrete merits lightweight and adiabatic. Therefore. we will expect that the current using ALC and Recycled Porous concrete has be similar thermal conductivity.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.86-91
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• 2016

This paper is concerned chiefly with the method of porous foam manufacture using basalt stone powder sludge. The hydrogen peroxide($H_2O_2$) of bloating agent has lots of problems to manufacture porous lightweight aggregate due to fast reaction rate with cement or calcium hydroxide($Ca(OH)_2$). The $H_2O_2$ injecting method using nozzle for manufacturing porous lightweight aggregate is proposed, in this study. This method is to inject $H_2O_2$ at the pressure of 10 MPa on upper side of slurry mixing materials such as stone powder sludge and quick-lime(CaO) by injector. The specimen was dried in furnace at $100^{\circ}C$ for 1 hour and cured at ambient temperature for 30 days. We analyzed the characteristics including specific gravity and water absorption. The experiments were found that the porous foam has low specific gravity, high water absorption and uniform distribution of porous more than manufactured foam by general bloating methods.

• Journal of Powder Materials
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• v.22 no.3
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• pp.197-202
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• 2015

In this study, porous stainless steel (STS316L) sintered body was fabricated by powder metallurgy method and its properties such as porosity, compressive yield strength, hardness, and permeability were evaluated. 67.5Fe-17Cr- 13Ni-2.5Mo (wt%) powder was produced by a water atomization. The atomized powder was classified into size with under $45{\mu}m$ and over $180{\mu}m$, and then they were compacted with various pressures and sintered at $1210^{\circ}C$ for 1 h in a vacuum atmosphere. The porosities of sintered bodies could be obtained in range of 20~53% by controlling the compaction pressure. Compressive yield strength and hardness were achieved up to 268 MPa and 94 Shore D, respectively. Air permeability was obtained up to $79l/min{\cdot}cm^2$. As a result, mechanical properties and air permeability of the optimized porous body having a porosity of 25~40% were very superior to that of Al alloy.

• Journal of Powder Materials
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• v.18 no.4
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• pp.327-331
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• 2011

In order to fabricate the porous metal with controlled pore characteristics, unique processing by using metal oxide powder as the source and camphene as the sublimable material is introduced. CuO powder was selected as the source for the formation of Cu metal via hydrogen reduction. Camphene-based CuO slurry, prepared by milling at $47^{\circ}C$ with a small amount of dispersant, was frozen at $-25^{\circ}C$. Pores were generated subsequently by sublimation of the camphene. The green body was hydrogen-reduced at $200^{\circ}C$ for 30 min, and sintered at $500-700^{\circ}C$ for 1 h. Microstructural analysis revealed that the sintered Cu showed aligned large pore channels parallel to the camphene growth direction, and fine pores are formed around the large pore. Also, it showed that the pore size was controllable by the slurry concentration.

• Journal of Powder Materials
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• v.15 no.4
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• pp.308-313
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• 2008

Al-Ni alloy nano powders have been produced by the electrical explosion of Ni-plated Al wire. The porous nano particles were prepared by leaching for Al-Ni alloy nano powders in 20wt% NaOH aqueous solution. The structural properties of leached porous nano powder were investigated by nitrogen physisorption, X-ray diffraction (XRD) and transmission Microscope (TEM). The surface areas of the leached powders were increased with amounts of AI in alloys. The pore size distributions of these powders were exhibited maxima at range of pore diameters 3.0 to 3.5 nm from the desorption isotherm. The maximum values of those were decreased with amounts of Al in alloys.

• Journal of Powder Materials
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• v.19 no.4
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• pp.259-263
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• 2012

Dependence of the freeze-drying process condition on microstructure of porous W and pore formation mechanism were studied. Camphene slurries with $WO_3$ contents of 10 vol% were prepared by milling at $50^{\circ}C$ with a small amount of dispersant. Freezing of a slurry was done in Teflon cylinder attached to a copper bottom plate cooled at $-25^{\circ}C$. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at $800^{\circ}C$ for 30 min, and sintered in the furnace at $900^{\circ}C$ for 1 h. After heat treatment in hydrogen atmosphere, $WO_3$ powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about $70{\mu}m$ which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores with dendritic structure due to the growth of camphene dendrite depending on the degree of nucleation and powder rearrangement in the slurry.