• Title/Summary/Keyword: ${\beta}$-spodumene

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

  • Lee, Sang-Jin;Park, Ji-Eun
    • Journal of Powder Materials
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    • v.18 no.1
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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.

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 (실리케이트 광물을 이용한 내열충격성 LAS계 세라믹스의 제조에 관한 연구: (II) Sillimanite, Kaolin 및 Pyrophyllite족 광물을 이용한 Spodumene 분말합성)

  • 박한수;조경식;문종수
    • Journal of the Korean Ceramic Society
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    • v.31 no.7
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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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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 (LAS계 내열충격성 재료의 미세구조 제어(II): $Li_2O{cdot}4B_2O_3$ 프릿트 첨가가 ${\beta}$-Spodumene의 미세구조 및 열팽창특성에 미치는 영향)

  • 박정현;김현민;이화선
    • Journal of the Korean Ceramic Society
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    • v.29 no.7
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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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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 (LAS계 내열충격성 재료의 미세구조 제어(III): Li2O.4B2O3 첨가가 카올린을 공급원으로하여 합성한 $\beta$-Spodumene의 미세구조 및 열팽창특성에 미치는 영향)

  • 박정현;김현민;이화선
    • Journal of the Korean Ceramic Society
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    • v.29 no.8
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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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Effect of modifiers on the properties of glass-ceramics containing coal bottom ash (석탄 바닥재가 포함된 결정화 유리의 특성에 미치는 수식제의 영향)

  • Kang, Seung-Gu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.20 no.1
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    • pp.53-57
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    • 2010
  • The influence of CaO addition on the crystallization temperature, crystal types, and microstructure of L-A-S ($Li_2O-Al_2O_3-SiO_2$) glass-ceramics system fabricated from a coal bottom ash, produced at thermal power plant, was studied. The glass transition and crystallization temperatures were shifted to the higher temperature position with increasing CaO content in a non-isothermal analysis using a DTA. The major crystalline phases of L-A-S glass-ceramics system produced were identified as ${\beta}$-spodumene ($LiAlSi_2O_6$) and eucryptite ($LiAlSiO_4$). The glass-ceramics showed a bulk and surface crystallization behavior at a time. With increasing CaO content, the ${\beta}$-spodumene peak in XRD increased and some CaO-related phases were formed. The surface crystal grown from the exterior to the center in glass-ceramics showed various shapes by amount of CaO added. Some cracks were generated at the glass-ceramics containing CaO above 9 wt% due to the mismatch of thermal expansion coefficients between a ${\beta}$-spodumene and CaO-related crystal phases.

Fabrication of Low TEC Machinable Ceramics using Domestic Pyrophillite (국내산 납석을 이용한 저팽창성 Machinable Ceramics의 제조)

  • 김재국;양삼열;정창주
    • Journal of the Korean Ceramic Society
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    • v.28 no.9
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    • pp.730-738
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    • 1991
  • Machinable ceramics containing ${\beta}$-spodumene crystal was fabricated by melting method using domestic pyrophyllite. Raw materials were batched by molar ratio of 8:2, 7:3, 6:4, and 5:5 for fluorophlogopite and ${\beta}$-spodumene. These compounds were melted at 1450$^{\circ}C$ for 1 hr and formed in graphite mold. Base glasses were heat-treated according to 2-step schedule which was determined from DTA, XRD analysis and SEM observation. Fabricated machinable ceramics have excellent themal, chemical properties and machinability.

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Studies on Properties with Different Filler and Content in Pb-free Sealing Frit for Electronic Devices

  • An, Yong-Tae;Choe, Byeong-Hyeon;Ji, Mi-Jeong;Jang, U-Seok;Lee, Jun-Ho;Hwang, Hae-Jin
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.181-181
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    • 2009
  • 전자부품용 Pb-free sealing frit의 열팽창계수를 기판에 matching 시키기 위하여 음의 열팽창계수를 가지고 있는 $\beta$-Eucryptite, $\beta$-Spodumene를 합성하여 filler로 첨가하였다. 합성된 filler는 저온소성용 유리프리트의 높은 열팽창계수를 조절하기 용이하고, 유리프리트와 복합화 하여 소성하면 낮은 열팽창계수로 인한 우수한 열충격 저항성을 갖는다. Filler로써 $\beta$-Eucryptite, $\beta$-Spodumene의 결정성을 향상시키기 위해 $1250^{\circ}C$에서 5 시간 동안 유지하는 합성공정을 3회 반복 진행한 후 XRD를 사용하여 결정성을 분석하였고, TMA를 이용하여 filler 첨가량에 따른 유리프리트의 열팽장계수의 변화를 측정하였다. 또한, filler 입도와 함량에 따른 melting 특성을 분석하기 위해 Pill test를 진행하였으며, soda-lime glass 기판과의 접합면을 SEM을 사용하여 관찰하였다.

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

  • Kim, Sang-Hun;Kang, Eun-Tae;Kim, Ung-Soo;Hwang, Kwang-Taek;Cho, Woo-Seok
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.5
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    • pp.218-224
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    • 2011
  • LAS ($Li_2O-Al_2O_3-SiO_2$) ceramics were sintered by a solid-state reaction. $CaCO_3$ and $ZrO_2$ were added to the ${\beta}$-spodumene ($Li_2O-Al_2O_3-4SiO_2$) composition of the LAS system for enhancement of sintering behavior and mechanical strength, respectively. We have investigated the sintering characteristics, microstructures, mechanical properties and thermal expansion characteristics according to the change of the amount of additive and sintering temperature of the ${\beta}$-spodumene. At 0.1 mol% $CaCO_3$, the densification of ${\beta}$-spodumene was significantly improved. At 0.04 mol% $ZrO_2$, the strength of ${\beta}$-spodumene was also improved. For all the selected all compositions, the thermal expansion coefficient was measured by a dilatometer, which revealed 1.2 to $1.7{\times}10^6/^{\circ}C$.

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

  • Kim, Sang-Hun;Kang, Eun-Tae;Kim, Ung-Soo;Hwang, Kwang-Taek;Cho, Woo-Seok
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.1
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    • pp.57-63
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    • 2012
  • $Al_2TiO_5$ ceramics were sintered by a solid-state reaction. LAS (${\beta}$-spodumene) and $Fe_2O_3$ were added to the $Al_2TiO_5$ composition for enhancement of sintering behavior such as mechanical strength and thermal shock resistance. The sintered body was much densified by addition of LAS and $Fe_2O_3$ because LAS formed the liquid-phase and $Fe_2O_3$ suppressed the grain growth. We have systematically investigated the sintering characteristics, microstructures, mechanical properties, and thermal shock resistance according to the change of the amount of additive. When the additive of LAS (20 wt%)-$Fe_2O_3$ was added to $Al_2TiO_5$, it confirmed that superior mechanical properties of the fracture strength of over 120 MPa and the thermal shock resistance of over $1,200^{\circ}C$ were achieved.

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

  • 장현명;김광수;정창주
    • Journal of the Korean Ceramic Society
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    • v.28 no.5
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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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