• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.58-58
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• 2005

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.199-200
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• 2005

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.201-201
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• 2005

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.55-57
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• 2005

• Journal of the Korean Ceramic Society
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• v.18 no.1
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• pp.3-12
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• 1981

A glass-ceramics based on blast-furnace slag, with some additives to the theoretical composition in order to control properties of mother glass and the heat treatment conditions, has been investigated. The raw materials in this study were blast-furnace slag, serpentine, feldspar and quartz as mother glass ingredients. Titanium dioxide and chromite were used as the nucleating agents. Batch compositions of the prepared glasses and ceraming conditions were found by trial and error method. The optimum conditions were confirmed by analyzing several measured physical properties such as density change during heat treatment, microhardness of slag-ceramics prepared, viscosity change of glass at heat treatment temperatures, nucleation density change, dilatometric properties, differential thermal analysis, identification of the grown crystal and crystal sizes. The batch composition feasible to prepare slag-ceramics was 40% of blast-furnace slag, 25% of serpentine, 18% of feldspar and 17% of silica sand. Three percent titanium dioxide and 1% chromite of the mother glass were added as nucleating agents. The ceraming conditions under which the slag-ceramics having considerably good properties can be developed found as: "The glass was heated at 75$0^{\circ}C$ for 2 hours for nucleation, and the temperature was raised up to 1, 00$0^{\circ}C$ with a rate of 0.75$^{\circ}C$/min for crystal growth.owth.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1182-1186
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• 1997

La0.8Ca0.2Cr0.98O3 powder was prepared using the modified Pechini process. Various crystalline phases formed during thermal decomposition were investigated. (La,Ca)CrO4 phase, first formed from the precursor, was transformed to (La,Ca)CrO3 and CaCrO4 above 80$0^{\circ}C$, which remained up to 110$0^{\circ}C$. However, only (La,Ca)CrO3 phase consisting of orthorhombic and intermediate rhombohedral polymorphs was observed after sintering at 125$0^{\circ}C$. The specimens sintered at 140$0^{\circ}C$ exhibited 98% of relative density and rather wide grain size distribution with average grain size of 3-4 ${\mu}{\textrm}{m}$. Densification and grain growth of the specimens observed above 125$0^{\circ}C$ were presumably attributed to liquid phase sintering resulted from melting of Ca3(CrO4)2 phase.

• Journal of the Korean Society for Precision Engineering
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• v.2 no.3
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• pp.41-46
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• 1985

The behavior of the burn-on in sand mold has been investigated by varying the pouring metal, bonding materials, additive materials and molding sand. The results obtained from thease experiments are as follows; 1) The burn-on layer of silica sand decreased in order of carbon steel, gray cast iron and stainless steel, and thease burn layer proceeded mostly by producing FeO. 2) The burning reaction of silica sand mold in carbon steel castings declined with increasingly bentonite content, but water-glass scarcely took part in the burn-on reaction. 3) The addition of feldspar and seacoal to silica sand promoted the inhibiting burn-on. 4) The burn-on layer of sand mold decreased of silica sand, chromite sand and olivine sand.

• Journal of the Korean Ceramic Society
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• v.17 no.3
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• pp.151-157
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• 1980

Crystallization phenomena of glasses of fused natural basalt rocks were studied by DTA, X-ray phase analysis, electron microscopy, and other techniques. Crystallization was catalyzed by the addition of either chromite ore or $P_2O_5$, both up to 5 wt %. Various heat treatments were used, and their influences on controlling the microstructures and properties of the products were studied to develop high strength glass-ceramic material of the $CaO-Al_2O_3(Fe_2O_3)-MgO(FeO)-SiO_2$ system from the domestic basalts. Magnetite precipitates were found to be a nucleation initiator in every case of the crystallization. Diopside, anorthite, clinoenstatite and monticellite were identified as silicate crystalline phases contained in the crystallized products. The crystallite size was in the range of 0.1-2.5$\mu\textrm{m}$. The fine crystallites were approximately cubic, but large crystallites were either plate or needle shape. The thermal expansion coefficient, microhardness and modulus of rupture of glass-ceramics were ranged from 78.5 to 81.8$\times$10-7 cm/cm/$^{\circ}C$, from 820 to 930kg/$\textrm{mm}^2$, and from 1800 to 2800kg/$\textrm{cm}^2$, respectively.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.957-960
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• 2010

본 연구에서는 중금속 크롬($Cr^{+6}$)이 포함된 흑색안료(Copper Chromite Black)를 공침공정을 이용하여 무독성의 Fe 화합물로 대체한 환경친화적인 블랙(흑색)안료를 개발하였다. 안료제조를 위하여 인체에 무해한 화합물($MnCO_3$, Fe(OH)$_3$, CuO)을 원료로 사용하였으며, 가스소성, Ring-Mill에 의한 습식분쇄 그리고 건조과정을 통하여 흑색안료를 제조하였다. 안료의 평가는 제품의 품질을 결정하는 색상과 착색력을 최우선으로 선정하여 색차계로 고찰하였다. 연구결과, 공침공정으로 제조한 원료를 $950^{\circ}C$에서 12시간 동안 가스소성을 한 후 건조와 분쇄공정(습식)을 거쳐 흑색안료를 제조하였을 때, 최적의 색 선명도, 착색력 및 입도($1{\mu}m$ 이하)를 가진 것으로 나타났다.

• Journal of Korea Foundry Society
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• v.4 no.2
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• pp.134-139
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• 1984

25% 크롬주철의 제조에 필요한 중요사항을 실험한 결과 다음 결론을 얻었다. 1) Sound 한 제품을 얻기 위하여는 Riser의 Modulus 가 제품 Modulus에 대해 1.1 배 이상이어야 한다. 2) 선수축율은 측정 결과 18/1,000 이었으며, 3) 주입온도는 $1440^{\circ}C\;{\sim}\;1460^{\circ}C$가 적당하며 후육제품은 가급적 낮은 쪽으로 박육제품은 높은 쪽으로 주입온도를 선택하는 것이 바람직하다. 4) 형상이 단순한 제품은 상온에서 해체할 수 있으나 형상이 복잡한 제품은 $500^{\circ}C\;{\sim}\;400^{\circ}C$ 사이에서 해체한 후 로에 장입 로냉하므로 Crack발생을 피할 수 있다. 5) 본 실험에서 주형 재료의 효과는 Chromite Sand에 Zircon Base의 도형재의 적용이 가장 효과적 이었으나 Silica Sand 적용으로도 미려한 표면을 얻을 수 있었다.