• 제목/요약/키워드: Al2O3 sol-gel

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Sol-Gel 법에 의한 $Li_2O-Al_2O_3-TiO_2-SiO_2$ 계 다공성 결정화 유리의 제조 : (II) Sol-Gel 법에 의해 제조된 $Li_2O-Al_2O_3-TiO_2-SiO_2$ 계 괴상겔의 결정화 (Preparation of Glass-Ceramics in $Li_2O-Al_2O_3-TiO_2-SiO_2$ System by Sol-Gel Technique : (II) Crystallization of $Li_2O-Al_2O_3-TiO_2-SiO_2$ Monolithic Gel Prepared by Sol-Gel Method)

  • 조훈성;양중식
    • 한국세라믹학회지
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    • 제32권4호
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    • pp.507-515
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    • 1995
  • The monolithic dry gels of the Li2O-Al2O3-TiO2-SiO2 system were prepared by the sol-gel technique using metal alkoxides as starting materials to obtain monolithic glass-ceramics at low temperature without melting. Activation energy for the crystal growth of the gel with 6.05% TiO2, nucleating ageng, for the preparation of Li2O-Al2O3-TiO2-SiO2 system glass-ceramic was 101.14kcal/mol. As a result of the analysis of DTA & XRD, it was confirmed that the crytallization of Li2O-Al2O3-TiO2-SiO2 system glass-ceramic was the most efficient when 6.05% TiO2, nucleating agent, was added. $\beta$-eucryptite solid solution crystals and $\beta$-spodumene solid solution crystals were detected in the sample heat treated above 85$0^{\circ}C$. The sintered gel heat treated at 85$0^{\circ}C$ had the specific surface area of 185$m^2$/g, the pore volume of 0.19cc/g and the average pore radius of 20.8$\AA$. This shows that the sintered gel is also comparatively porous material. In temperature range of 25~85$0^{\circ}C$ thermal expansion coefficient of the specimen which was crystallized for 10hrs at 85$0^{\circ}C$ was 6.7$\times$10-7/$^{\circ}C$, which indicated that the crystallized specimen was turned out to be the glass-ceramic with low thermal expansion.

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Boehmite Sol-Gel법에 의한 $\alpha$-Al2O3 분말제조시 Seeding 효과 (Effect of Seeding on Preparation of $\alpha$-$\alpha$-Al2O3 Powders by Boehmite Sol-Gel Process)

  • 이홍림;오한석;김경룡
    • 한국세라믹학회지
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    • 제24권5호
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    • pp.447-452
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    • 1987
  • ${\alpha}$-Al2O3 powder was produced at 1000$^{\circ}C$ by the boehmite sol-gel process with seeding 2 wt% ${\alpha}$-Al2O3. The processes and mechanisms of fornation of ${\alpha}$-Al2O3 was investigated using DTA/TG, XRD, TR spectroscopy and thermodynamic analysis. The specific surface area of the obtained ${\alpha}$-Al2O3 was 16.3㎡/g.

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졸-겔법을 이용하여 제조한 Al2O3-ZrO2 세라믹스에 미치는 하소온도의 영향 (Effect of Calcination Temperature on Al2O3-ZrO2 Ceramic Prepared by Sol-Gel Process)

  • 우상국;김종희
    • 한국세라믹학회지
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    • 제24권5호
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    • pp.423-430
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    • 1987
  • Characteristics of Al2O3-ZrO2 powders prepared by sol-gel process and their sintering behavior were investigated as a function of calcination temperature. The sol-gel processed powders were calcined at 800, 900, 1000, 1100, 1200$^{\circ}C$, and analyzed by X-ray diffraction technique. Pore size and distribution of green compact of the calcined powders were measured by mercury porosimeter. It is suggested that the optimal temperature of calcination for the sintering of Al2O3-ZrO2 powder prepared by sol-gel process is 1100$^{\circ}C$. In the Al2O3-17vol.% ZrO2 sintered specimen, which was sintered at 1600$^{\circ}C$ for 2hrs in air, 69vol.% tetragonal phse existed.

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Sol-Gel법에 의한 Al2O3-ZrO2계 분말제조에 있어서 결정화 및 Seeding 효과 (Effects of Crystallization and Seeding on Characteristics of Al2O3-ZrO2 Powder Prepared by a Sol-Gel Method)

  • 오한석;홍기곤;이홍림
    • 한국세라믹학회지
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    • 제25권4호
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    • pp.373-379
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    • 1988
  • $\alpha$-Al2O3-15m/o ZrO2 powder was prepared by a sol-gel method from boehmite and zirconium acetate. The transformation temperature of boehmite to $\alpha$-Al2O3 in the system Al2O3-ZrO2 was increased due to the coupled crystallization. On the other hand, the transformation temperature from boehmite to $\alpha$-Al2O3-15m/o ZrO2 could be prepared at 110$0^{\circ}C$ for 100min. The specific surface area of the product of $\alpha$-Al2O3-15m/o ZrO2 was 13.2$m^2$/g.

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Sol-Gel법에 의한 $Li_2O-Al_2O_3-TiO_2-SiO_2$계 다공성 결정화 유리의 제조 : (I) Sol-Gel 방법에 의한 $Li_2O-Al_2O_3-TiO_2-SiO_2$계 다공성 겔체의 제조 (Preparation of Glass-Ceramics in $Li_2O-Al_2O_3-TiO_2-SiO_2$ System by Sol-Gel Technique : (I) Preparation of Porous Monolithic Gel in $Li_2O-Al_2O_3-TiO_2-SiO_2$ System by Sol-Gel Method)

  • 조훈성;양중식;권창오;이현호
    • 한국세라믹학회지
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    • 제30권7호
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    • pp.535-542
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    • 1993
  • It was investigated in this study that a preparation method, activation energy, surface area, pore volume, pore size distribution and DTA analysis of the dry gel in process of producing monolithic porous gel in Li2O-Al2O3-TiO2-SiO2 system by the sol-gel technique using metal alkoxides. Activation energy for gellation according to the variation of water concentration and the kind of catalysts ranged from 10 to 20kcal/mole. Monolithic dry gels were prepared after drying at 9$0^{\circ}C$ when the amount of water for gellation was 4~8 times more than the stoichiometric amount, that was necessary for the full hydrolysis of the mixed metal alkoxide. The specific surface area, the pore volume, the average pore radius of the dried gel at 18$0^{\circ}C$ according to the various kinds of catalyst were about 348~734$m^2$/g, 0.35~0.70ml/g and 10~35$\AA$, respectively. It showed that the dry gels were porous body. As a result ofthe analysis of DTA, it was confirmed that the exothermaic peaks at 715$^{\circ}C$ and 77$0^{\circ}C$ was clue to the crystallization of dried gel.

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Sol-gel dip coating에 의한 ZnO 투명전도막의 특성고찰 (Properties of Zinc oxide films prepared by sol-gel dip coating)

  • 김범석;구상모;김창열
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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    • pp.191-191
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    • 2003
  • 가시광선영역에서 높은 광학적 투명도를 갖는 n-type 반도체인 ZnO 박막은 넓은 범위에서 응용되고 있다. 현재 ZnO 박막의 특성 향상을 위하여 여러 원소(Al, Ga)의 도핑을 시도하고 있다. 특히 Al-doped ZnO 박막은 sol-gel dip coating에 의해서도 높은 전기전도도와 투과율로 활발히 연구되고 있다 본 논문에서는 여러 도핑농도를 갖는 Al-doped ZnO 박막이 sol-gel dip coating법에 의해 준비되었다. Al-doped ZnO 박막은 zinc acetate [Zn($CH_3$COO$_2$)ㆍ2$H_2O$] powder 와 여러 도핑농도를 갖는 aluminum nitrate (Al(NO$_3$)$_3$ㆍ9$H_2O$) powder를 알코올에 용해하여 $H_2O$, Ethylene glycol, Ethylene diamine 등을 첨가하여 제조하였다 XRD와 SEM (Scanning electron microscope)이 막의 상형성 분석을 위해 이용되었으며, 가시광선 영역 투과율(UV/VIS spectrophotometer)과 표면전기저항(four point probe)이 주요 특성으로 분석되었다.

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졸-겔법에 의한 $Al_2O_3$.$2SiO_2$ 유리의 제조 (Preparation of $Al_2O_3$.$2SiO_2$ glass by the sol-gel process)

  • 이준;지응업;조동수
    • 한국세라믹학회지
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    • 제20권1호
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    • pp.3-12
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    • 1983
  • In the present study an attempt was made to synthesize the $Al_2O_3$.$2SiO_2$ glass in which atomic ratio is Al:Si=1:1 by sol-gel process. And at such a low temperature as 55$0^{\circ}C$ clear amorphous gel derived glass with Si-O-Al bonding was obtained. $Si(OC_2H_5)_4$ and $Al(NO_3)_3$.$9H_2O$ were used as the precursor and among the mutual solvents only n-butanol gave good results for the synthesis of the gel derived glass. Partial hydrolysis of TEOS with one-fold mol of $H_2O$ prior to the reaction with aluminum nitrate gave the better results., Total oxide content to the total reactants by weight was affective to the results.

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Sol-Gel법에 의한 $ZrO_2/Al_2O_3$ 복합체의 제조에 미치느 Seeding 효과 (The Effect of Seeding on Preparation of $ZrO_2/Al_2O_3$ Composite by Sol-Gel Method)

  • 김선욱;주치홍;장윤식;손영국;박홍채
    • 한국세라믹학회지
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    • 제30권7호
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    • pp.571-577
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    • 1993
  • The effect of $\alpha$-Al2O3 seeding on preparation of zirconia/alumina gel fragment prepared by sol-gel processing was characterized through XRD, SEM, TG/DTA and IR analysis. Aluminum isopropoxide and zirconium butoxide were used as starting materials. $\alpha$-Al2O3 seeding restrained grain growth of alumina and zirconia, and decreased tetragonal to monoclinic phase transformation of zirconia on cooling. Therefore, fine zirconia-toughened alumina composite having the relative sintered density of about 98% of theoretical at 140$0^{\circ}C$ for 2h could be obtained.

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졸-겔법을 이용한 Al2O3가 분산된 TZP 단섬유의 제조 (Fabrication of Discontinuous Al2O3-Dispersed TZP Fibers by a Sol-Gel Method)

  • 심수만
    • 한국세라믹학회지
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    • 제52권1호
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    • pp.56-60
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    • 2015
  • Discontinuous, polycrystalline $Al_2O_3$-dispersed TZP fibers were prepared by the centrifugal spinning of a colloidal $ZrO_2$ sol containing Y and Al nitrates and poly(vinyl alcohol). Factors affecting the rheological properties of the sols, such as sol concentrations, aging, and the amounts and types of additives, were investigated by measuring the shear viscosities. The flow characteristics of the sols were studied in relation to the spinnability by measuring the viscosity with respect to the shear rate. The spinnability was obtained through the addition of a polymer which increases the viscosity to a range of optimum viscosity values for spinning. Aging the sols containing the additives did not noticeably change the sol viscosities at room temperature up to 30 days. The flow behavior of the spinnable sols progressively changed from nearly Newtonian to pseudoplastic with an increase in the sol concentration.