• 한국결정성장학회지
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• 제7권4호
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• pp.626-631
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• 1997

하동고령토($Al_2O_3-SiC-C$)를 출발원료로하여 AlSiCa내화재 원료를 합성하였다. 하동고령토와 탄소분말을 혼합하여 수소분위기하에서 반응시킨결과, $1300^{\circ}C$에서$Al_2O_3-SiC-C$ 복합체가 힙성되기 시작하여$1400^{\circ}C$에서 완전 합성되었고, $SiO_2$에 대한 최적carbon량은 mole비로 1:4이었다. 합성시 알루미나 용기에 탄소분말을 충전시키지 않을 때는 미합성부분이 없이 밝은 녹색을 띈 $\beta$-SiC(cubic form) 를 형성함을 확인하였다.

• 한국결정학회지
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• 제8권2호
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• pp.89-96
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• 1997

본 연구는 fine ceramics의 합성법을 traditional ceramics의 합성에 적용하는 연구의 일환으로 내화재료용 mullite합성법을 개발하고자 한다. 출발원료로는 알루미나 함량이 높은 하동 kaolin 과 boehmite를 사용하였으며 합성법은 gel coating법을 사용하였다. 그 결과 1350℃에서 미반응 silica와 corundum이 존재하지 않는 단일상의 mullite를 합성할 수 있었으며 1700℃로 소성한 분말의 경우 mullite 생성율은 80%로 나타났다. 이 때 부피비중은 2.56, 흡수율은 1.9%, 상온꺽임강도는 169 MPa의 값을 나타내어 우수한 내화재료로의 활용이 가능하다고 생각된다.

• 한국세라믹학회지
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• 제12권4호
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• pp.19-28
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• 1975

In order to obtain the superior refractory setter having better spalling resistance, cordierite was synthesized from domestic raw materials. Raw mixtures were fired between 125$0^{\circ}C$ and 140$0^{\circ}C$, and qualitative determination of crytallization was investigated by x-ray diffraction analysis. The results obtained are as follows; 1) The optimum batch composition of synthesized cordierite is 80.5% of Hadong kaolin (pink), 14% of Kyulsung tromolite talc and 5.5% of magnesia clinker, and the firing temperature is 1375$^{\circ}C$. 2) The composition of the refractory setter which exhibits the best values for the thermal properties is 40% of synthesized cordierite, 30% of kaolin chamotte(contains more than 60% of mullite), and 30% of Japanese clay. 3) The optimum particle size distribution of ternary mixture consists of 50% of coarse articles (3.327-1.168mm), 25% of intermediate particles (1.168-0.208mm) and 25% of fine particles (0.208-0.000mm).

• 한국세라믹학회지
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• 제24권4호
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• pp.349-356
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• 1987

${\beta}$-Sialon powder was synthesized by the simultaneous reduction and nitridation of Hadong kaolin at 1350$^{\circ}C$ in N2-H2 atmosphere, using graphite as a reducing agent. The synthesized ${\beta}$-Sialon powder was pressurelessly sintered over 1450-1850$^{\circ}C$ in nitrogen atmosphere. The average particle size of ${\beta}$-Sialon powder was about 4.5$\mu\textrm{m}$. The relative density, M.O.R., fracture toughness and micro-hardness of ${\beta}$-Sialon ceramics sintered at 1800$^{\circ}C$ for 1 hour were 92%, 36 kpsi, 2.8MN/㎥/2 and 13.3 GN/㎡, respectively. The critical temperature difference (ΔT) in water quench thermal shock behavior showed about 375$^{\circ}C$ for the synthesized ${\beta}$-Sialon ceramics.

• 한국세라믹학회지
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• 제17권3호
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• pp.141-144
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• 1980

Thermal expansion property of $SiO_2-Al_2O_3$ system consisted of Muan clay, Hadong Pink Kaolin and Dangjin Silica was studied. Specimens were heated at the constant rate of 18$0^{\circ}C$/hr to the max. temperatures of 115$0^{\circ}C$ to 130$0^{\circ}C$ with an interval of $25^{\circ}C$, and matured for 3hrs. The result of X-Ray diffraction analysis showed that main crystals formed were $\alpha$-quartz, $\alpha$-cristobalite and mullite. Linear thermal expansion was measured at 90$0^{\circ}C$. The results of the linear thermal expansion were decreased regularly with the increase of the sintering temperature in accordance with the following equation. $y=5$\chi$\perp1100^{\circ}$. Where $\chi$ is amounts of kaolin (wt%), and y is temperature of the changing point of linear thermal expansion.

• 대한화학회지
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• 제8권4호
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• pp.169-178
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• 1964

現在 國內에서 使用되고 있는 主要 窯業原料들에 對한 基礎的 data가 不足하므로 이에 國內 主要 窯業工場의 使用量을 基準으로 하여 約 40 種의 鑛物을 試料로 設定하고 그 基礎的 硏究를 하였다. 設定된 試料에 對하여 化學分析, D.T.A.試險, X-ray 廻折試險 및 粒度分析試驗을 行하고 그 結果 및 解析의 一部를 第 1報로서 發表한다. 모든 試料鑛物은 그 試驗結果를 結晶構造的 見地에서 鑛物學的으로 다루어 解析되었는데 特히 本 硏究의 結果 河東白土는 halloysite 라는 設$^{29}$과 一致하였으며 또한 國內 蠟石은 그 主成分 鑛物이 pyrophyllite 質, kaolin 質 및 muscovite 質의 3 者로 分類되어야 한다는 것이 밝혀졌다. 또한 本 第 1報에서 다루지 못한 詩料들, 疑問으로 남은 點들, 電子顯微鏡寫眞 및 光學的 試驗結果는 次報에서 다루기로 한다.

• 한국세라믹학회지
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• 제31권5호
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• pp.572-580
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• 1994

With low thermal expansion coefficients, eucryptite (Li2O.Al2O3.2SiO2) and spodumene (Li2O.Al2O3.4SiO2) in LAS ceramic system show good thermal shock resistance. In this study, sillimanite or kaolin group silicate minerals and Li2CO3 were used as starting materials, and if necessary SiO2 or Al2O3 were added for making stoichiometrically formed specimens. By this process, eucryptite powders were synthesized and characterized. The powder mixtures of lithiumcabonate and silicate minerals calcined at 80$0^{\circ}C$ for 2 hrs were made into powder compacts. $\beta$-Eucryptite single phase was formed via intermediate phases of Li2SiO3 and LiAlO2 et al, by heating at 110$0^{\circ}C$ or 120$0^{\circ}C$ for 10 hrs from those powder compacts. When using the sillimanite group minerals, Virginia kyanite or andalusite was reacted to form eucryptite at 120$0^{\circ}C$and CMK International kyanite were completed at 110$0^{\circ}C$. When kaolin group minerals were used, it was found that the synthesizing temperature (100$0^{\circ}C$) of $\beta$-eucryptite from the mixture of New Zealand white kaolin was lower than that from Hadong pink kaolin (110$0^{\circ}C$). The Microstructure of systhesized powder showed the irregular lump shape such as densed crystallines.

• 한국세라믹학회지
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• 제36권1호
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• pp.82-88
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• 1999

본 연구에서는 fine ceramics의 합성법을 traditional ceramics 합성에 적용하여 합성한 내화재료용 mullite에 광화제를 첨가함으로서 광화제가 mullite 생성에 미치는 영향을 관찰하고자 한다. 출발물질로 하동 kaolin과 boehmite를 사용하였으며, 여기에 광화제로 MnO와 TiO2를 액상으로 첨가하였다. 그 결과 3.5 wt% MnO를 첨가한 경우, 1,25$0^{\circ}C$에서 미반응 silica와 alumina가 존재하지 않는 단일상의 mullite를 합성할 수 있었으며, TiO2 첨가시 2~3.5wt% MnO의 경우 mullite 생성 온도를 약 10$0^{\circ}C$ 낮출 수 있었다. 이때의 mullite 생성율은 1$650^{\circ}C$에서 84%이며, 부피 비중과 흡수율 및 상온에서 꺾임강도는 각각 2.72, 0.27%, 180MPa을 나타내어 광화제를 첨가하지 않은 경우보다 특성도 향상함을 알 수 있었다.

• 약학회지
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• 제29권4호
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• pp.176-182
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• 1985

As a part of the studies on adsorptive properties of Korean halloysite clays, Hadong white clays of premium grade were examined for geometric pore structured by mercury porosimetry and for specific surface areas by nitrogen adsorption according to the BET procedure. Three size fractions of the native clay sample were derived from passage BS #100, #200 and #325 meshes, respectively. Several parameters lhus observed in relation to the pore structures are shown below: 1. The size fraction of BS #100, #200 and #325 show internal pore volumes of 25.3, 30.2 and $35.0m^2g^{-1}$, respectively. 2. In the distribution curves of the cumulative pore volume against pore diameter, it has been shown that the larticle sizes, the steeper the distribution over the larger ranges of pore diameters. The converse is true the smaller particles. 3. Internal pore areas increase with decrease in pore sizes. It follows that the pores having diameters of $\leq$0.1$\mu\textrm{m}$ are responsible for more than 90% of the total pore area. 4. The behaviour of nitrogen adsorption can be best described by BET type IV isotherm. Further, the hysteresis loops of the adsorptiondesorption curves become narrower with decresing particle sizes. 5. The specific surface areas observed for the fractions of BS #100, BS #200 and BS #325 are 34.6, 35.4 and 43.2m $^2g^{-1}$, respectively. and the calcined clay of BS #325 has a specific surface area near $30.4m^2g^{-1}$.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.382-387
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• 1998

Triaxial compression tests were run to study on the undrained strength characteristics of fiber mixed kaolin clay(Hadong). The influence of various test parameters such as amount and aspect ratio(ratio of length to diameter) of fiber, confining stress was also investigated. Test results showed that the increase in aspect ratio was increased in deviator stress at failure, but no effect on pore water pressure at failure. Deviator stress at failure was also increased at 0.5％ mixing ratio(weight fraction of fiber to that of soil solid) of fiber but it was, thereafter, decreased and wits reached to constant after 2％ mixing ratio. On the contrary, Pore water pressure at failure was increased as mixing ratio of fiber was greater than 1%. Deviator stress and pore water pressure of both clay and fiber mixed clay(FMC) at failure were increased as confining stress was increased. Deviator stress of FMC at failure was about 10％ larger than that of clay, but pore water pressure of FMC at failure was almost similar to that of clay.