• Title/Summary/Keyword: Alkoxide

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Fabrication and Sintering Characteristic of MgO-Al2O3-SiO2 System Ceramic Raw Materials(Mullite, Spinel and Cordierite) II. Powder and Mechanical Properties of Mg-Al Spinel Ceramics Prepared by Alkoxide (MgO-Al2O3-SiO2계 요업원료(Mullite, Spinel, Cordierite)의 제조 및 소결특성 II. Alkoxide로 제조한 Mg-Al Spinel분말 및 소결체의 특성)

  • 김창은;이홍림;안용진;김배연
    • Journal of the Korean Ceramic Society
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    • v.26 no.5
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    • pp.593-600
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    • 1989
  • Fine spinel powder was prepared from the Mg-Al double alkoxide synthesized using magnesium powder, aluminum foil and sec-butyl alcohol. This powder was compared with powder prepared by mixing two commercial alkoxides. The spinelization was started at 50$0^{\circ}C$ and was almost completed at 100$0^{\circ}C$ with a good crystallinity in the double alkoxide system. In mixed alkoxide system, homogeneous spinel powder was not obtained and MgO existed as a second phase because of solubility and hydrolysis rate differences of two alkoxides. The relative density of specimen prepared by double alkoxide was 99% and specimen prepared by mixed alkoxide was 95%. The modulus of rupture of specimens prepared by double alkoxide and mixed alkoxide was 49.9kg/$\textrm{mm}^2$ and 41.6kg/$\textrm{mm}^2$, respectively.

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Hydrolysis Rate Study of Chelated Ti Alkoxide by Using U.V. Spectrophotometer (자외선 흡수대를 이용한 Chelated Ti Alkoxide의 수화반응 연구)

  • 김선욱;윤만순;송인호
    • Journal of the Korean Ceramic Society
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    • v.28 no.12
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    • pp.975-980
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    • 1991
  • Chelated titanium alkoxides are hydrolysed showly and stable enough to prepare multicomponent gels of titania without its precipitation due to the fast hydrolysis of Ti alkoxide. The alkoxy groups of chelated titanium alkoxide are hydrolysed as fast as that of titanium alkoxide but the chelating groups are stable even in aqueous solution. The chelating groups showed different rates of hydrolysis in aqueous ammonia solution and water added one. Those rates were monitored with UV-VIS spectrophotometer by using their unique absorption bands before and after hydrolysis.

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Preparation of the Fine Alumina Powder from the Synthisized Aluminum-Sec-Butoxide by the Alkoxide Sol-Gel Process (합성한 Aluminum Sec-Butoxide로부터 알콕사이드졸겔법에 의한 알루미나 미분말의 제조)

  • 김창은;이해욱;정형진;김구대;박노경
    • Journal of the Korean Ceramic Society
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    • v.25 no.6
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    • pp.585-592
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    • 1988
  • Aluminum sec-butoxide was synthesized from aluminum foil and alcohol. The characteristics of the alumina powder prepared from the synthesized alkoxide by the Yoldas method were studied. As a result of measuring the synthesized aluminum sec-butoxide by GC, the purity of the synthesized alkoxide was 98.7% on the basis of commercial alkoxide and the yield was 78.5%. A127-MASNMR analysis shows that powders dried at 9$0^{\circ}C$ and $\alpha$-Al2O3 have 6-cordinated structure and ${\gamma}$-Al2O3 has 4-coordinated structure. The characteristics of alumina powder prepared from the synthisized alkoxide showed the same characteristics with the alumina powder prepared from the commercial alkoxide.

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Synthesis of Hydroxy-terminated Poly(propylene carbonate) (Hydroxy-terminated Poly(propylene carbonate)의 합성)

  • Jung, S.M.;Moon, J.Y.;Park, D.W.;Park, S.W.;Lee, J.K.
    • Applied Chemistry for Engineering
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    • v.9 no.2
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    • pp.273-277
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    • 1998
  • The synthesis of hydroxy-terminated poly(propylene carbonate)(HTPPC) was performed by the reaction of propylene carbonate(PC) with alcohol initiator using metal alkoxides, crown ethers and quaternary onium salts as catalysts. The effects of catalyst structure, types and concentration of alcohol, and solvent were investigated. Among the alkoxide catalysts tested, the ones with higher Lewis acidity and with more nucleophilic alkoxide anion showed higher catalytic activity. Mixed catalysts of metal alkoxied and crown ether showed higher conversion of PC than metal alkoxide alone. Quaternary onium salts of bulky cation exhibited higher catalytic activity. High polar solvent showed higher yield of HTPPC and the yield increased with the decrease of [PC]/[Initiator] ratio.

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A Study on the Ge Substituted LAS Ceramics Using Metla Alkoxide (금속알콕사이드를 이용한 LAS계 내열세라믹스의 제조시 Ge 성분의 치환에 관한 연구)

  • 장성중;김형태;이응상
    • Journal of the Korean Ceramic Society
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    • v.32 no.11
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    • pp.1233-1240
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    • 1995
  • LAS system, which is difficult to be sintered, was densified by using the powder synthesized from metal alkoxides. Sinterability, thermal and mechanical properties were improved through synthesizing the complex oxide powder from the addition of Ge as an alkoxide. As a result, the synthesizing and sintering temperature of the LAS system lowered by about 10$0^{\circ}C$ and its modulus of rupture (MOR) increased twice higher compared to the sample from the oxide by the direct method.

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Preparation of the LAS Ceramics for Heat Resistance using Metal Alkoxide (I) (금속 Alkoxide를 이용한 LAS계 내열세라믹스의 제조에 관한 연구(I))

  • 김형태;이응상
    • Journal of the Korean Ceramic Society
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    • v.30 no.12
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    • pp.987-992
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    • 1993
  • In order to synthesize the heat resistance ceramics of LAS system, we studied on preparing the fine powder with homogeneity by sol-gel method using metal alkoxide. Various results were obtained depending on the composition and process. When the amount of H2O added at initial stage is higher than 10mol/$\ell$, and when the amount of catalyst is 0.1mol/$\ell$, the particle size of synthesized hydrate becomes finer. On condition that partial prehydrolysis time of TEOS is more than 50 hours, the monosized fine powder is obtained(below 1${\mu}{\textrm}{m}$).

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Synthesis of Glasses from Metal Alkoxide (금속 알콕시드로부터 유리의 합성에 관한 연구)

  • 최석진;김병훈
    • Journal of the Korean Ceramic Society
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    • v.21 no.2
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    • pp.127-134
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    • 1984
  • Basic research on the formation of monolithic glasses from metal alkoxide has been done concerning gelling of silicon alkoxides and dehydration of those gells. The felling time were increased with increasing of Carbon number of alkyl radical of alkoxide and am-ount of water and the lower pH value of water. Large portions of water and organic materials were rem-oved below 25$0^{\circ}C$ and shrinkage of glass took place above 80$0^{\circ}C$ Therefore heating up to 25$0^{\circ}C$ and above 75$0^{\circ}C$ must be done gradually with rate of 0.5$^{\circ}C$/min.

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Critical factors in sol-gel transition of silicon metal alkoxide solutions (Silicon metal alkoxide 용액의 sol-gel 전이에서 중요인자)

  • ;;Hiromitsu Kozuka;Sumio Sakka
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.5 no.4
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    • pp.332-342
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    • 1995
  • The important factors of reaction conditions in sol-gel transition of silicon alkoxide solution have been reviewed and discussed on the basis of Raman study. Various factors such as type of catalyst, alkoxide, solvent, drying control chemical additive and water content affect the conversion mechanism in sol-gel process.

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