• Journal of Magnetics
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• 제16권3호
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• pp.318-321
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• 2011

A new Fe-based amorphous compound powder was prepared from Fe-Si-B amorphous powder by crushing amorphous ribbons as the first magnetic component and Fe-Cr-Mo metallic glassy powder by water atomization as the second magnetic component. Subsequently by adding organic and inorganic binders to the compound powder and cold pressing, the new Fe-based amorphous compound powder cores were fabricated. This new Fe-based amorphous compound powder cores combine the superior DC-Bias properties and the excellent core loss. The core loss of 500 kW/$m^3$ at $B_m$ = 0.1T and f = 100 kHz was obtained When the mass ratio of FeSiB/FeCrMo equals 3:2, and meanwhile the DC-bias properties of the new Fe-based amorphous compound powder cores just decreased by 10% compared with that of the FeSiB powder cores. In addition, with the increasing of the content of the FeCrMo metallic glassy powder, the core loss tends to decrease.

• The Korean Journal of Ceramics
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• 제1권1호
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• pp.35-39
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• 1995

Yttrium aluminum garnet(YAG) powders were synthesized by spray-drying of the hydroxides coprecipitated from a mixture of aqueous solutions of $Al(NO_3)_3.9H_2O \;and\; Y(NO_3)_3.6H_2O$ Phase formation in the powders during heat treatments and their sintering charactristics were investigated. In the powder obtained by washing the hydroxides before spray-drying, a metastable yttrium aluminum hexagonal (YAH) phase was first crystallized and then transformed into YAG as temperature was increased. The formation of YAH was attributed to a deviation in compositions of the particles from the starting composition of YAG. However, the powder prepared without washing step contained a stable yttrium aluminum monoclinic(YAM) phase in addition to YAG due to a large deviation from the starting composition. A powder compact of a single phase YAG was pressureless-sintered for 4 hrs at $1700^{\circ}C$ and the density was 93% of the theoretical density.

• 한국세라믹학회지
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• 제31권9호
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• pp.957-968
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• 1994

Manufacturing process of porous glass by the filler method was studied. Commercial soda-lime-silicate glass powder was mixed with inorganic salt as the filler such as KCl, K2SO4, Na2SO4. Sintering shrinkages of mixed powders with the variation of sintering temperature were compared, and the effects of the fillers to shrinkages of mixed powder were increased in the order of Na2SO4${\mu}{\textrm}{m}$ of pore diameter were manufactured when the filler sizes 100~200 ${\mu}{\textrm}{m}$. The open pore volume of porous glass is determined by the quantity of filler and porous glasses having open pore volume between 30 and 70 vol% are available. Available sintering temperature range for preparation of porous glass is from the softening temperature of the glass powder to eutectic melting temperature of DTA curve of mixed powder.

• 한국식생활문화학회지
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• 제10권5호
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• pp.443-448
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• 1995

Korean fresh elephant-foot (Amorphophalus konjak K. Koch) and its powder were analyzed and compared with foreign samples to investigate the physico-chemical characteristics of Korean konjak. The Korean fresh konjak contained 80.6% of moisture content and most of the solid component comprises much of sugar, protein and trace of fat and fibre. The mannan content of Korean konjak powder is far smaller than those of Japanese and Chinese konjak powder. The analysis of the Korean konjak revealed that glutamic acid, aspartic acid and arginine included 45% of total amount, and other amino acid was incresaed with the order of valine, serine, leucine and glycine. The Korean konjak contained a moderate amount of K component and other inorganic component was larger with the order of P, Na and Ca. The yield of refined powder obtained from dried chip of Konjak was 61.0% in Korean one and 57.5% in Chinese one. The degree of lightness of Chinese konjak powder was slightly higher than that of Korean product, but the difference could not be recognized by naked eye.

• 한국세라믹학회지
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• 제38권12호
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• pp.1085-1092
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• 2001

고효율 AC powder EL 소자를 초저가형과 저전력 소모형으로 분류하여 막의 두께와 제조된 유기결합제에 따라 스크린 프린팅법으로 제조하였다. 제조된 소자의 광전기적 특성을 평가하기 위하여 인가 주파수는 400Hz~1kHz, 인가 전압은 50~300 $V_{rms}$까지 변화시켜 휘도 및 전류밀도를 측정하였다. 주파수 및 전압공급원은 정현파 발생 장치로서 frequency generator를 이용하였다. 또한 휘도는 luminometer 의해 측정되었으며 전류밀도 측정을 위하여 multimeter를 사용하였다. 초저가형 AC powder EL 소자의 경우에는 가소제를 첨가하지 않고 발광층의 두께는 45~50$\mu\textrm{m}$이며 유전층의 두께는 약 10$\mu\textrm{m}$에서 43cd/$m^2$ 정도의 휘도와 20$\mu$A/$cm^2$정도의 전류밀도를 얻을 수 있었으며 저전력 소모형 AC powder EL 소자의 경우에는 15wt의 가소제 첨가하에 발광층의 두께는 45~50$\mu$m이며 유전층의 두께는 15~20$\mu$m에서 74cd/ $m^2$정도의 휘도와 30~40$\mu$A/ $m^2$정도의 전류밀도를 얻을 수 있었다. 또한 수명시간에 있어서 본 연구에서 제조한 AC powder EL 소자가 타사 제품보다 절대적으로 우수한 특성을 보였다.다.

• 한국세라믹학회지
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• 제53권4호
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• pp.386-392
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• 2016

Heat insulation plates of fumed silica were prepared by mixing fumed silica, SiC powder and chopped glass fiber by a high speed mixer followed by pressing of the mixture powder in a stainless steel mold of $100{\times}100mm$. Composition of the plates, particle size of SiC, and type of inorganic binder were varied for observation of their contribution to heat insulation of the plate. The plate was installed on the upper portion of an electric furnace the inside temperature of which was maintained at $400^{\circ}C$ and $600^{\circ}C$, for investigation of heat transfer through the plate from inside of the electric furnace to outside atmosphere. Surface temperatures were measured in real time using a thermographic camera. The particle size of SiC was varied in the range of $1.3{\sim}17.5{\mu}m$ and the insulation was found to be most excellent when SiC of $2.2{\mu}m$ was incorporated. When the size of SiC was smaller or larger than $2.2{\mu}m$, the heat insulation effect was decreased. Inorganic binders of alkali silicate and phosphate were tested and the phosphate was found to maintain the heat insulation property while increasing mechanical properties.

• 한국전기전자재료학회논문지
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• 제35권2호
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• pp.178-183
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• 2022

For enhancing the flame-retardant properties of wallpapers, we developed an organic-inorganic hybrid solution with ZrSiO₄ as a functional ceramic powder, coated on non-woven fabric using dip coating, spray coating, and slot-die coating methods. Their flame retardant properties were characterized by a 45° combustion tester, which is manufactured according to the flame-retardant performance standard (KOFEIS 1001 and KS F 2819). In organic-inorganic hybrid solution, with increasing the concentration of acid-catalyst (acetic acid), the precipitation of ZrSiO₄ powders increased, and the flame retardant properties decreased. The highest flame retardant result was obtained for the solution adding 5 wt% acetic acid. The optimization of the coating method and coating number resulted in the most excellent flame-retardant properties being obtained for the non-woven fabric coated for 5 or 7 times by dip coating method, and their flame-retardant properties corresponded to class 2 flame-retardant performance of wallpapers.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.128-134
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• 2005

This study was performed to evaluate the strength and durability properties of recycled concrete containing water - redispersible copolymer powder(WRP) and blast furnace slag powder(BSP) [RCWS]. Material used were cemente, recycled coarse aggregare, natural fine aggregate, water-redispersible copolymer powder, blast-furnace slag powder. Especially, Water-redispersible powder was used for blending with Inorganic binders such as cemente, gypsum and hydrated lime etc. First of all, Mixed ratio method of RCWS made Two Type. One was called type-1 which used to BSP content 5% and WRP(Water-redispersible powder) content 0%, 1%, 2%, 3%, 4%, 5%, 6%. respectively. Another was called Type-2 which used to BSP(blast furnace slag powder)content 10% and WRP(Water-redispersible powder) content 0%, 1%, 2%, 3%, 4%, 5%, 6%. respectively. According to the experimental results of (RCWS), Incase Type-2 at curing age 28days, Compressive strength, pulse velocity and dynamic modulous of elasticity were shown higher than Type-1 and The more WRP content increasing($0%{\sim}6%$) was the lower Compressive strength, Pulse velocity and Dynamic modulous of elasticity. Water absorption ratio was in the range of $3.85%\;{\sim}\;3.23%$, it was almost equal to Type-1, 2 but Increasing the WRP content($0%{\sim}6%$), The water absorption ratio is decreased.

• 한국세라믹학회지
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• 제25권4호
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• pp.357-363
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• 1988

Ccompaction and sintering behavior of highly pure PSZ powders were investigated by laying the stress on the granulation processes. The particle size of coprecipitated PSZ powder was so fine that the agglomeration was severely formed during drying and calcing step and by this agglomeration differential sinering was occurred. The methanol dispersion of precipitates was the good method of avoiding severe agglomeration formed during drying process because of small surface tension than water. But perfect deagglomeraton was not possible due to high surface area of powders. So homogenization by granulation was needed, and among the method spray granulation was the most desirable to obtain homogeneous compacts and subsequent flaw-free ceramics.

• 한국세라믹학회지
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• 제40권9호
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• pp.837-841
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• 2003

Duplex microstructure of zirconia and alumina has been achieved via an organic-inorganic solution technique. Zirconium 2,4-pentanedionate, aluminum nitrate and polyethylene glycol were dissolved in ethyl alcohol without any precipitation. The organicinorganic precursor gels were turned to porous powders having volume expansion through explosive, exothermic reaction during drying process. The volume expansion was caused by abrupt decomposition of the organic groups in the gels during the vigorous exothermic reaction. The volume expanded, porous powders were crystallized and densified at 1500$^{\circ}C$ for 1 h. At the optimum amount of the PEG polymer, the metal cations were well dispersed in the solution and a homogeneous polymeric network was formed. The polymer content also affected on the specific surface area of the synthesized powder and the grain size of the sintered composite.