• Korean Journal of Materials Research
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• v.12 no.8
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• pp.595-599
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• 2002

A homogeneous and stable, amorphous-type, anorthite (CaO $Al_2$$O_3$ $2SiO_2$)powder was synthesized by an organic-inorganic steric entrapment route. Polyvinyl alcohol ( PVA) was used as an organic carrier for the precursor ceramic gel. The PVA content, its degree of polymerization and type of silica sol had a significant influence on the calcination and crystallization behavior of the precursors. For densifiction and crystallization at low temperature, porous and soft, amorphous-type anorthite powder was planetary milled for 20h. The milled powder crystallized to stable anorthite phase and densified to a relative density of 94% below $1000^{\circ}C$. In the development of crystalline phases of the planetary milled powder, omisteinbergite phase was unusually observed at $900^{\circ}C$, and then anorthite was observed at $950^{\circ}C$. The sintered anorthite had a thermal expansion coefficient of $4.6$\times$10^{-6}$ /$^{\circ}C$ and a dielectric constant of 7.5 at 1 MHz. Finally, the anorthite synthesized by the new process is expected to be an useful material for low-firing ceramic substrate.

• Journal of the Korean Ceramic Society
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• v.16 no.2
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• pp.83-88
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• 1979

The Anorthite is useful compound for some ceramic industries but it is difficult to produce Anorthite because of its high melting point (1553$^{\circ}C$) and narrow firing range. On this study, glass frit was added to Anorthite batch composition to widen firing range and lower melting point. After mixing a glass frit $(Na_2O-CaO-6SiO_2)$ with Anorthite, it was melted and quenched. Ratio of Anorthite vs. glass frit was 9 : 1, 8.5 : 1.5, 8 : 2, 7.5 : 2.5, 7 : 3. In those batch composition added amount of $No_2O$ were between 1.3wt.% and 3.9wt.%. To find the thermal change of the quenched, D.T.A. was surveyed. The quenched were fired at various vitrification temperature and detected by X-Raydiffraction analysis. With addition of glass frit, firing range and vitrification temperature of Anorthite was 100~15$0^{\circ}C$ and 1050~115$0^{\circ}C$ respectively. Optimum amount of glass frit was 20wt.% for the upper mentioned.

• Journal of the Korean Ceramic Society
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• v.16 no.2
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• pp.77-82
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• 1979

Diopside-Anorthite body was easily synthesized at relatively low temperature 1225℃, compared with the synthesizing temperature 1425℃ of Anorthite. Of Diopside-Anorthite body, the synthesizing temperature was considered to be higher than 1225℃ because Gehlenite, probably formed at 1220℃, was detected by X-ray diffraction. This body has excellent physical and electrical properties, i.e. electric resistivity (1.2×1014Ωcm), low dielectric constant (6.26) and low thermal expansion coeffcient (61.9×10-7/℃). It's hardness was good enough for electrical subsidiary. In addition, this body, Diopside-Anorthite, has exellent properties for heat resisting wares.

• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.55-60
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• 2017

An anorthite-based traditional ceramic was developed by adding secondary flux materials to a mixture of kaolin and $CaCO_3$ in order to minimize the deformation during the sintering process. Three flux materials, feldspar, talc, and frit, were evaluated by comparison with two commercial chinaware bodies. Anorthite body with glass frit exhibited poor firing shrinkage. Poor mechanical properties (modulus of rupture, MOR < 30 MPa) was observed for the bodies with feldspar. Another anorthite body was formulated with wollastonite as a Ca source. The fired body showed a MOR of 81 MPa and a shrinkage rate of 6% when wollastonite was added up to 50%. In the XRD analysis, the phase ratio between anorthite and quartz was the highest in the specimen with 50% wollastonite addition. Homogeneous and relatively small closed pores were observed in the microstructural analysis. These results suggest that a ceramic body formulated with 50% kaolin and 50% wollastonite can be fired at $1200^{\circ}C$ with a 6% firing shrinkage rate, giving rise to minimal sintering deformation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.11
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• pp.864-868
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• 2010

Among LTCC material for substrate, the crystallized anorthite system was mainly studied as high strength material. However, specific factors that have affected on strength of material were studied insufficiently on anorthite system. In this study, the composition of anorthite glass was Ca-Al-Si-Zn-O. The changes of phase and microstructure were observed with the amount and the particle size of glass and the sintering temperature. It was studied that the factors affected on the strength of material. Phases of anorthite and $ZnAl_2O_4$ were formed with the increase of sintering temperature. The $Al_2O_3$ phase was increased with $Al_2O_3$ amount, acted as filler, and the strength of material is increased with $Al_2O_3$ phase. But phases of anorthite and $ZnAl_2O_4$ didn't affect on the strength of material. In the case of 60 vol% glass amounts and below $3.2\;{\mu}m$ of glass particle size, the strength of material was decreased. It is thought that the decrease of strength was due to non-homogeneous mixing between glass powder and filler.

• Journal of the Korean Ceramic Society
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• v.20 no.2
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• pp.153-160
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• 1983

This study was carried out to research the change of mineral phases and the characteristics(apparent specific gra-vity water absorption firing shrinkage modulus of rupture thermal expansion and specific dielectric constant) of the sintered bodies manufactured by kaolin and limestone. Samples were composed of the same theoretical composition as it of anorthite and fired up to 145$0^{\circ}C$ Investigated the change and micro-structure of the mineral phases by XRD and SEM the characterisdtics of the sintered bodies by TMA Automatic Capacitance Bridge and etc. The results were as follow. 1. Reactions of sintering are occurred between 860-95$0^{\circ}C$ and 1200-138$0^{\circ}C$ and state of bloating is occurred at 1410-145$0^{\circ}C$ 2. For the inclusion of feldspar and its fine particles of materials the temperature of producing and collapsing is decreased. 3. Pseudo-wollastonite and gehlenite are formed about 95$0^{\circ}C$ 4. At 114$0^{\circ}C$ anorthite are begin to forming and increase continuously to 138$0^{\circ}C$. Above 141$0^{\circ}C$ content of anorthite are decreased. 5. The variations of bending strength with sintering temperature reflect similar trend of sintered contraction and in-crease continuously from 120$0^{\circ}C$. At 145$0^{\circ}C$ reached about 680kg/cm2. 6. Specific dielectric constant$($\varepsilon$_s)$ of specimen sintered at 141$0^{\circ}C$ is 7.12 and that value is most favorable.

• Journal of the Korean Ceramic Society
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• v.38 no.4
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• pp.351-359
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• 2001

배향 입자층과 비배향 입자층이 상호적층된 알루미나 적층복합체를 연속 테입캐스팅 및 상압소결에 의해 제조하였다. 알루미나의 미세구조 배향을 위하여 알루미나 판상입자를 배향물질(template)로 사용하였으며, 알루미나의 입자배향 거동에 미치는 액상의 영향을 알아보기 위해 anorthite(CaAl$_2$Si$_4$O$_{8}$)를 첨가하였다. 적층체 내의 알루미나 입자배향을 X-선 회절법으로 분석한 결과 (006)면과 (1010)면으로 배향되어 있었다. 액상조성이 첨가되지 않은 경우와 비교시 anorthite를 첨가한 경우 입자배향층 내에는 액상으로 인한 큰 기공이 생성되었으며 배향도는 감소되었다. 그러나, 액상조성으로 anorthite가 첨가되어 입자배향이 이루어진 적층체 계면에서는 입자배향으로 인한 효과적인 균열전파 제어 거동이 관찰되었다.

• Journal of the Korean Ceramic Society
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• v.36 no.11
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• pp.1243-1251
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• 1999

Densification behavior and microstructural evolution during the liquid-phase sintering of alumina-anorhite system were investigated as a function of MgO addition. When MgO component was added in either alumina or anorthite glass powder the aspect ratio of alumina grains decreased and concurrently the are of flat interface which was formed as a result of contact solid alumina gains rather increased. Consequently addition of MgO component in the Al2O3-amorthite system brought about suppression of the rearrangement of solid grains during the liquid phase sintering and then densification of specimens was also retarded.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.75.1-75
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.86.2-86.2
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• 2007