• Title/Summary/Keyword: 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.

Spodumene Single Crystal Growth by FZ Method (Floating Zone법에 의한 Spodumene 단결정 성장)

  • 강승민;신재혁;한종원;최종건;전병식;오근호
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.3 no.2
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    • pp.162-166
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    • 1993
  • Spodumene$(LiAlLi_2O_6)$ single crystal was grown by Floating Zone process using the image furnace having the halogen lamp as heat sources. The crystal had the dimension of 50~60mm length and 6~8mm diameter. The colors of as-grown crystals were green, black and pale green respectively. The composition of the crystal was analized by XRD and FUR measurement. Growth orientation was examined by Laue back reflection pattern and for measuring the light transmittance, OPtical transmittance was measured.

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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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The Study on Fabrication of LAS System Ceramics for Thermal Shock Resistance from Silicate Minerals (III) Sintering Characteristics of Eucryptite and Spodumene (실리케이트 광물을 이용한 내열충격성 LAS계 세라믹스의 제조에 관한 연구 (III) Eucryptite와 Spondumene 소결특성)

  • 박한수;조경식;문종수
    • Journal of the Korean Ceramic Society
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    • v.32 no.2
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    • pp.171-182
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    • 1995
  • Five eucryptite and ten spodumene compositional powders were syntehsized from three sillimanite group, two kaolin group, and five pyrophyllite group silicate minerals. Those powders were isotatically pressed and fired at 1200~135$0^{\circ}C$ for 2 hrs, and then the sintered bodies were characterized. Silicate minerals with molar ratio of Al2O3 to SiO2 correspond to those of eucryptite and spodumene are kaolin and pyrophyllite group silicate minerals, respectively. Sintering characteristics of eucryptite from kaolin group and spodumene from pyrophyllite group mineral were superior to those from other silicate minerals. Eucryptite sintered bodies with 95~97% relative densities and densified microstructures can be obtained using Hadong pink kaolin as starting materials by sintering over broad temperature zone(1250~135$0^{\circ}C$). The eucryptite sintered bodies which were fired at 130$0^{\circ}C$ for 2hrs, from Hadong pink kaolin had within 3.0wt% microstructural compositional variations compaired with stoichiometric compound, and had good negative thermal expansiion property with -3.55$\times$10-6/$^{\circ}C$ thermal expansion coefficient. Spodumene sintered bodies which were prepared from pyrophyllite group silicate minerals, had dense microstructures and high densities by densification through liquid phase sintering with enlarged temperature range. The specimens which were fired at 130$0^{\circ}C$ for 2 hrs from Gusipyrophillite, had dense microstructure with crystallines mainly, and low thermal expansion property with 0.62$\times$10-6/$^{\circ}C$ thermal expansion coefficient. The porous texture and residual glass phase in LAS system ceramics which were prepared from silicate minerals, tend to increase the thermal expansion properties of sintered bodies to positive direction.

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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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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.