• 제목/요약/키워드: LAS (${\beta}$-spodumene)

검색결과 10건 처리시간 0.017초

Sol-Gel 반응으로 유도된 LAS의 상 생성과 점성 특성 (Phase Formation and Rheological Characteristics of LAS Derived from the Monophasic Sol-Gel Route)

  • 장현명;김광수;정창주
    • 한국세라믹학회지
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    • 제28권5호
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    • pp.365-372
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    • 1991
  • LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and Li-salt with H2O in alcohol (EtOH+2-Propanol) medium. Effects of important reaction parameters on the properties of sol and gel-derived LAS were examined. The crystallization of the sol-gel derived LAS with ${\beta}$-spodumene composition began at ∼600$^{\circ}C$, and a series of polymorphic transformations occurred as temperature was increased to 1100$^{\circ}C$: amorphous LAS\longrightarrowhexagonal LiAl(SiO3)2\longrightarrow${\beta}$-spodumene. Lowering Li content in the gel enhanced densification and retarded the crystallization significantly. Optimum reaction conditions of LAS sol formation for thin coating applications were derived from rheological measurements, and these can be summarized as: H2O/total alkoxides molar ratio=4, pH=∼2.5, and aging time of ∼250h.

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고상반응법을 이용한 LAS계의 CaCO3와 ZrO2 첨가에 따른 소결체 특성 연구 (Sintered body characteristics of LAS by addition of CaCO3 and ZrO2 using a solid-state reaction)

  • 김상훈;강은태;김응수;황광택;조우석
    • 한국결정성장학회지
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    • 제21권5호
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    • pp.218-224
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    • 2011
  • 저열팽창 특성을 갖는 난소결 물질인 LAS($Li_2O-Al_2O_3-SiO_2$)계를 고상 소결로 제조하였다. LAS계의 ${\beta}$-spodumene($Li_2O-Al_2O_3-4SiO_2$) 조성에 소결 조제로 $CaCO_3$를 첨가하였고, 강도 증가를 위하여 $ZrO_2$를 첨가하였다. 첨가제의 양의 변화와 소결 온도의 변화에 따른 소결 특성, 미세 구조, 기계적 특성 및 열팽창 특성에 대하여 조사하였다. 0.1 mol%의 $CaCO_3$을 첨가하였을 때, 치밀화가 증진됨을 미세구조 관찰에 의해 확인하였으며, $ZrO_2$의 첨가로 강도가 증진됨을 확인하였다. Dilatometer로 측정한 열팽창 계수는 선택된 전 조성에서 값이 $1.2{\sim}1.7{\times}10^6/^{\circ}C$임을 확인하였다.

LAS (β-spodumene)와 Fe2O3 첨가에 따른 Al2TiO5의 소결체 특성 연구 (Characteristics of the sintered body of the Al2TiO5 with addition of LAS (β-spodumene) and Fe2O3)

  • 김상훈;강은태;김응수;황광택;조우석
    • 한국결정성장학회지
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    • 제22권1호
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    • pp.57-63
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    • 2012
  • $Al_2TiO_5$에 LAS(${\beta}$-spodumene)와 $Fe_2O_3$를 첨가하여 고상법으로 세라믹 소결체를 제조하였다. $Al_2TiO_5$에 첨가된 LAS는 액상을 형성하고, $Fe_2O_3$는 입자 성장을 억제시켜 소결체를 치밀화하였다. 첨가제의 양을 변화시켜 소결특성, 기계적 특성 및 열충격 특성에 대하여 조사하였다. $Fe_2O_3$가 20 wt% 첨가된 LAS를 $Al_2TiO_5$에 20 wt% 첨가하였을 때, 꺽임 강도는 120 MPa 이상이었고, 열충격에 대한 저항성은 $1200^{\circ}C$ 이상으로 우수함을 확인하였다.

Polyvinyl Alcohol 폴리머 용액법으로 합성한 스포듀민 분말의 특성연구 (Characteristics of Spodumene Powders Synthesized by Polyvinyl Alcohol Solution Technique)

  • 이상진;박지은
    • 한국분말재료학회지
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    • 제18권1호
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    • pp.35-40
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    • 2011
  • LAS-system ceramic powder, spodumene ($Li_2O{\cdot}Al_2O_3{\cdot}4SiO_2$), was successfully synthesized by a chemical solution technique employing PVA(polyvinyl alcohol) as an organic carrier. The PVA content affected the microstructure of porous precursor gels and the crystalline development. The optimum PVA content contributed to homogeneous distribution of metal ions in the precursor gel and it resulted in the synthesis of glass free $\beta$-spodumene powder having a specific surface area of $7.57\;m^2/g$. The agglomerated $\beta$-spodumene powders were also enough soft to grind to fine powders by a simple ball milling process. The microstructures of the densified powder compacts were strongly dependant on the minor phases of spodumene solid solution and amount of liquid phase, which were formed from the inhomogeneous precursors.

LAS계 내열충격성 재료의 미세구조 제어(II): $Li_2O{cdot}4B_2O_3$ 프릿트 첨가가 ${\beta}$-Spodumene의 미세구조 및 열팽창특성에 미치는 영향 (A Study on the Microstructural Control of LAS Ceramics (II): Influence of L$Li_2O{cdot}4B_2O_3$ Frit Addition on the Microstructure and Thermal Expansion of ${\beta}$-Spodumene)

  • 박정현;김현민;이화선
    • 한국세라믹학회지
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    • 제29권7호
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    • pp.533-538
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    • 1992
  • Effect of Li2O.4B2O frit on the microstructural and thermal expansion behaviour of $\beta$-spodumene ceramics was investigated. With 4.0~8.0 wt.% frit addition, sintering temperature range was enlarged and densification was enhanced through liquid phase sintering. As the amount of frit addition was increased, thermal expansion coefficient was increased to 1.72$\times$10-6$^{\circ}C$-1 of its highest value, which indicated that the increment of thermal expansion coefficient due to the second phase was constrained.

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LAS계 내열충격성 재료의 미세구조 제어(III): Li2O.4B2O3 첨가가 카올린을 공급원으로하여 합성한 $\beta$-Spodumene의 미세구조 및 열팽창특성에 미치는 영향 (A Study on the Microstructural Control of LAS Ceramics (III) : Influence of Li2O.4B2O3 Frit Addition on the Microstructure and Thermal Expansion of $\beta$-Spodumene made from Kaolinite)

  • 박정현;김현민;이화선
    • 한국세라믹학회지
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    • 제29권8호
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    • pp.646-650
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    • 1992
  • Effect of Li2O.4B2O3 frit addition on microstructural and thermal expansion behaviour of the $\beta$-spodumene ceramics made from kaolinite was investigated. With 2.0~4.0 wt% frit addition, the densification by liquid phase sintering caused low water absorption below 3% and enhancement of beding strength. As the amount of frit addition was increased, thermal expansion coefficient was increased to large scale, but in 2 wt% frit addition, its thermal expansion coefficient was constrained to 1.92$\times$10-6$^{\circ}C$-1.

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실리케이트 광물을 이용한 내열충격성 LAS계 세라믹스의 제조에 관한 연구: (II) Sillimanite, Kaolin 및 Pyrophyllite족 광물을 이용한 Spodumene 분말합성 (The Study on Fabrication of LAS System Ceramics for Thermal Shock Resistance from Silicate Minerals: (II) Preparation of Spodumene Powders with Sillimanite, Kaolin and Pyrophyllite Group Minerals)

  • 박한수;조경식;문종수
    • 한국세라믹학회지
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    • 제31권7호
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    • pp.784-794
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    • 1994
  • Though spodumene have a law theraml expension and good thermal shock resistance, its sintering temperature is too close to its melting point in the application for industral purpose. Solving the problems, impurities within the silicate minerals act as a frit during firing, so its densification is expected through enlargement of sintering temperature range. By the heat treatment of starting materials, mixtures of silicate mineral, lithium carbonate, if necessary SiO2 or Al2O3 were added for stoichiometric correction, in the range of 1000~125$0^{\circ}C$ for 10 hrs, $\beta$-spodumene single phase was synthesized. Mixtures with sillimanite group minerals, $\beta$-spodumene was formed at 120$0^{\circ}C$ or 125$0^{\circ}C$ via intermediate phases of petalite, Li2SiO3 and LiAlO2. For the case of kaolin group minerals, synthesis were completed at 110$0^{\circ}C$ for Hadon pink kaolin, 120$0^{\circ}C$ for New Zealand white kaolin, When pyrophyllite group minerals were used, those were at the range of 1000~125$0^{\circ}C$. Spodumene was completed at lowest temperature, 100$0^{\circ}C$ from the mixture of Wando pyrophyllite among them. Microstructure of synthesized powders showed the inrregular lump shape such as densed crystallines.

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가수분해-축합반응 및 콜로이드 혼합법으로 유도된 LAS gel의 치밀화와 결정화 특성 (Densification and Crystallization Characteristics of LAS Gels Prepared by the Hydrolysis-Condensation Reaction and the Mixed Colloidal Processing Route)

  • 김광수;장현명;정창주
    • 한국세라믹학회지
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    • 제28권11호
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    • pp.865-872
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    • 1991
  • LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and LiNO3 with H2O in alcohol (ethanol+2-propanol) medium. Lowering Li content by a factor of 1/2 significantly enhanced densification and retarded the crystallization of LAS gel by ~30$0^{\circ}C$. Dense LAS specimen with essentially pore-free microstructure was obtained by sintering the sol-gel derived gel at 80$0^{\circ}C$ for 4 h and annealing at 120$0^{\circ}C$ for 2 h. Similary, a mixed colloidal processing was attempted as a convenient, alternative route for the fabrication of dense LAS sintered body. The $\beta$-spodumene seeding (~0.8 ${\mu}{\textrm}{m}$) in the sol-gel derived LAS modified the sequence of phase transformations and lowered the temperature of crystallization by ~12$0^{\circ}C$. Combining the epitaxial seeding with the sol-gel process, we could lower the crystallization temperature to the sintering temperature range (~80$0^{\circ}C$) and, demonstrate a possibility of making the viscous sintering/crystallization as a continuous as a continuous unit process.

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졸-겔법에 의한 금속기판상의 $\beta$-spodumene 결정성유리의 박영도포와 원적외선상세성 (The Effect of Far Infrared Radiation of $\beta$-Spodumene Glass-Ceramics Flims Coated on Iron Substrate by Sol-Gel Technique)

  • 양중식;신현택;박종옥
    • 한국표면공학회지
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    • 제27권2호
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    • pp.99-108
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    • 1994
  • Films of glass-ceramics $Li_2O-Al_2O_3-SiO_2$(LAS)system were prepared on substrate of an iron plate(SCP) by sol-gel technique using metal alkoxide such as Si$(OC_2H_5)_4$,Al$(OC_2H_9)_3$) and Ti$(OC_2H_6)_4$). Sol which was made by means of simple spray coating, on the substrate was hydrolyzed at 75~$80^{\circ}C$ in moisture cabinet (80~90 % humidity) to form the multicomponent gel. The films up to about 0.8~1.0$mu extrm{m}$ in thickness can be obtained by repeating operation, spraylongrightarrowhydrolysis and condensationlongrightarrowdryinglongrightarrowheating and crystallization at $700^{\circ}C$ for 3~5min. The far-infrared radiation spectra of the coated films on substrate were examined by FT-IR and of films was also observed by scanning electron micrograph technique. The thermal evaluation of the gel-film is followed by TG/DTA measurements. The structure evaluation is followedd X-ray diffraction. These results suggest that this process is applicable to far-infrared radiat at thin film technique.

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실리케이트 광물을 이용한 내열충격성 LAS계 세라믹스의 제조에 관한 연구: (I) Sillimanite와 Kaolin족 광물을 이용한 Eucryptite 분말합성 (The Study on Fabrication of LAS System Ceramics for Thermal Shock Resistance from Silicate Minerals: (I) Preparation of Eucryptite Powders with Sillimanite Group, Kaolin Group Minerals)

  • 박한수;조경식;문종수
    • 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.

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