• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.292-293
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• 2006

$ZnNb_2O_6$ ceramics were sintered under the presence of zinc-borosilicate(ZBS) glass and resultant microwave dielectric properties were investigated with a view to applying the composition to LTCC technology. The addition of 10~30 wt% ZBS glass ensured successful sintering below $900^{\circ}C$. In general, increased addition of ZBS glass increased sinterability but it decreased the dielectric properties significantly due to the formation of an excessive liquid and second phases. The sintered $ZnNb_2O_6$ ceramics at $900^{\circ}C$ with 25 wt% ZBS glass demonstrated 15.8 in dielectric constant(${\varepsilon}_r$), 5,400 in quality factor($Q{\times}f_0$), and $-98\;ppm/^{\circ}C$ in temperature coefficient of resonant frequency(${\tau}_f$).

• 한국세라믹학회지
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• 제29권7호
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• pp.558-564
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• 1992

The effect of composed phase in the hot pressed CaO-MgO-Al2O3-SiO2 glass-ceramic has been investigated through microstructure studies, thermal, physical and mechanical properties. Sintering was done in the condition at the temperature range 900~95$0^{\circ}C$ for 20~120 mins under 7.5 MPa unilateral pressure. Sintered ceramics were composed of diopside, anorthite, residual glass and the portion of each phase was dependent on the sintering temperature and the holding time: as the temperature increases, the amount of diopside increased and then the rate of increase of diopside reduced with increasing anorthite. The thermal expansion coefficient of hot pressed was reduced with increasing crystallinity of hot pressed and was in the range of 6.69~7.46$\times$10-6 K-1 below $600^{\circ}C$. The elastic constant of hot pressed increased with increasing crystallinity up to about 80%, but after that was reduced due to the change of microstructure. The flexural strength of sintered ceramics was decreased with higher temperature and holding time, while the fracture toughness of those increased. It was shown that the physical and mechanical properties of hot pressed ceramic were related to the fraction of composed sintered ceramics, similar to a particulate composite, to the crystallinity of 80% of the glass-ceramic.

• 한국세라믹학회지
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• 제37권1호
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• pp.50-56
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• 2000

Precursor gels with the composition of xZrO2·(100-x)SiO2 systems (x=10, 20 and 30 mol%) were prepared by the sol-gel method. Kinetic parameters, such as activation energy, Avrami's exponent, n, and dimensionality crystal growth value, m, have been simultaneously calculated from the DTA data using Kissinger and Matusita equations. The crystallite size dependence of tetragonal to monoclinic transformation of ZrO2 was investigated using XRD, in relation to the fracture toughness. The crystallization of tetragonal ZrO2 occurred through 3-dimensional diffusiion controlled growth(n=m=2) and the activation energy for crystallization was calculated using Kissinger and Matusita equations, as about 310∼325±10kJ/mol. The growth of t-ZrO2, in proportion to the cube of radius, increased with increasing heating temperature and hteat-treatment time. It was suggested that the diffusion of Zr4+ ions by Ostwald ripening was rate-limiting process for thegrowth of t-ZrO2 crystallite size. The fracture toughness of xZrO2·(100-x)SiO2 systems glass ceramics increased with increasing crystallite size of t-ZrO2. The fracture toughness of 30ZrO2·70SiO2 system glass ceramics heated at 1,100℃ for 5h was 4.84 MPam1/2 at a critical crystaliite size of 40 nm.

• 한국결정성장학회지
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• 제21권5호
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• pp.210-213
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• 2011

$P_2O_5$ 함량에 따른 $5Na_2O-36CaO-10TiO_2-xP_2O_5$으로 구성된 glass-ceramic을 다음과 같은 방법으로 제조하였다: 1) 1 N HCl 용액 내에서 $Ca_3(PO_4)_2$와 $NaTi_2(PO_4)_3$ 간의 $Ca_3(PO_4)_2$ 결정을 2일간 추출하여 제거함. 2) Ag($NO_3$) 용액에서 1일간 $Na^+$ 이온을 $Ag^+$ 이온으로 이온 교환시킴. Glass-ceramic의 합성 여부를 SEM 및 XRD를 이용하여 확인하였다. Staphylococus aureus를 이용한 박테리아 실험 결과 3시간 이후에는 완전하게 박테리아가 제거됨을 확인할 수 있었다.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.712-717
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• 2014

Glass ceramic has a high mechanical strength and low sintering temperature. So, it can be used as a thick film substrate or a high strength insulator. A series of glass ceramic samples based on MgO-$Al_2O_3-SiO_2-ZrO_2$ (MASZ) were prepared by melting at $1,600^{\circ}C$, roll-quenching and heat treatment at various temperatures from $900^{\circ}C$ to $1,400^{\circ}C$. Dependent on the heat treatment temperature used, glass ceramics with different crystal phases were obtained. Their nucleation behavior, microstructure and mechanical properties were investigated with differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Vicker's hardness testing machine. With increasing the heat treatment temperature of MASZ samples, their hardness and toughness initially increase and then reach the maximum points at $1,300^{\circ}C$, and begin to decrease at above this temperature, which is likely to be due to the softening of glass ceramics. As the content of $ZrO_2$ in MAS glass ceramics increases from 7.0 wt.% to 13 wt.%, Vicker's hardness and fracture toughness increase from $853Kg/mm^2$ to $878Kg/mm^2$ and $1.6MPa{\cdot}m^{1/2}$ to $2.4MPa{\cdot}m^{1/2}$ respectively, which seems to be related with the nucleation of elongated phases like fiber.

• 한국콘텐츠학회논문지
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• 제18권2호
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• pp.290-300
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• 2018

색유리와 화장토를 이용한 새로운 기법발견의 주안점은 기존의 불편한 점을 개선해야 하기 때문인데 이는 도자기 소지와 유리의 상호물성 호환 관계에 있다. 말하자면 세로로 된 도자기 기물에는 색유리의 데코레이션 표현이 용이하나 가로로 된 기물에서는 녹아 흐르기 때문에 미적 표현이 제한을 받아왔다. 그래서 세로로 된 기물에 녹아 흐르지 않는 새로운 표현 방법의 발견이 주된 관점이다. 이를 보완한 새로운 방법은 화장토를 이용하여 색유리를 곱게 분쇄하여 희석한 후 붓으로 기벽에 칠하는 새로운 기법을 최초로 개발하였고 추가로 미적 완성도를 높이기 위해 상감기법과 귀얄기법을 적용하였다. 소성의 방법은 산화와 환원이고 소성방법에 따라 컬러가 다르게 발색 되었다. 특히 음각 된 색유리 표면을 부분부분 깎아낼 경우 독특한 붉은 갈색게열의 부드러운 그라데이션이 형성되었는데 이러한 효과를 작품 제작 뿐 아니라 산업자기에 확장 적용을 하기에도 좋을 것이다.

• 한국세라믹학회지
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• 제48권3호
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• pp.217-221
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• 2011

Glass-ceramic materials, which consist of glass matrix phase containing crystalline ${\beta}-Ca_3(PO_4)_2$ and ${\beta}-Ca_2P_2O_7$, have been prepared by heating at $750-900^{\circ}C$ of calcium phosphate invert glasses in the silica-free $CaO-P_2O_5-TiO_2-Na_2O$, system. With increasing heating temperature from 750 to $900^{\circ}C$, the crystallite size of precipitated ${\beta}-Ca_3(PO_4)_2$ in glass with $55CaO{\cdot}35P_2O_5{\cdot}3TiO_2{\cdot}7Na_2O$ (mol%) composition increased from 48 to 91 nm. With the extension of the immersion time in dilute acetic acid solution (pH = 5) to ${\geq}$200 min, the degree of dissolution of $Ca^{2+}$ and $P^{5+}$ ions in the glass-ceramics was linearly increased and the solution was constantly maintained at pH = ~7. Biomimetic nanostructured (62-88 nm in average dia.), sphere-shaped hydroxyapatite was homogeneously formed on the surface of the glass-ceramics when socked for 7-14 days in a Hanks' solution, indicating bioactivity of the prepared glass-ceramics.

• Journal of Electrical Engineering and information Science
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• 제3권1호
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• pp.68-72
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• 1998

The photomachinable glass-ceramics of Ag and CeO2 doped Li203-SiO2 (LAS)glass system was investigated as a function of UV irradiation time. After the expose and the non-exposed samples were heated, they went under crystalline phase with DTA, SEM, TEM and XRD of normal/high temperature. In this work, crystalline phases, microstructure and dielectric properties were studied under the various time of UV irradiation and heat treatment.

• 한국산학기술학회논문지
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• 제1권1호
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• pp.27-32
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• 2000

인산염계 Ag₂OㆍLi₂OㆍCaOㆍTiO₂ㆍP₂O/sub 5/ 조성에 CuO를 0.05∼l.5 mole 첨가하여 다공성 글래스 세라믹스를 제조하였으며. 제조된 모유리는 최적 핵형성을 위해 610℃. 최고 결정성장을 위해 840℃에서 열처리하였다. 1N-HC1에서 β-Ca₃(PO₄)결정상만을 선택적으로 용출하였으며 LiTi₂(PO₄)₃상과 AgTi₂(PO₄)₃결정상이 존재하는 Glass Ceramics를 제조하였다. 다공성 글래스 세라믹스의 항균효과 및 특성을 평가하였다. Staphylococcus aureus와 Salmonella typhi 균이 본 연구에 사용되었으며, 탁월한 항균효과를 나타내는 것으로 평가되었다.

• 한국세라믹학회지
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• 제41권12호
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• pp.915-920
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• 2004

[ $BaTi_{4}O_9$ ]계 세라믹스에 borosilicate계 유리 프리트를 첨가할 때 주결정상이 $BaTi_{5}O_{11}$로 변화되는 현상을 XRD와 TEM으로 분석하였다. Borosilicate계 유리 프리트가 $BaTi_{4}O_9$상으로부터 Ba 이온을 선택적으로 흡수함으로써 주상인 $BaTi_{4}O_9$ 상보다 Ti-rich인 $BaTi_{5}O_{11}$상으로 변화하는 것으로 추측하였다. 이와 같은 결과는 유리의 첨가량과 열처리 온도에 따라 영향을 받는데 $BaO-TiO_2$계의 Ti-rich 영역에 속하는 $Ba_{4}Ti_{13}O_{30},\;Ba_{2}Ti_{9}O_{20}$ 등의 결정상도 상변화 과정에 참여하고 있음을 관찰하였다. 중-고유전율 LTCC 조성개발을 위하여 유리 첨가에 의한 중-고유전율 모재료의 저온소결을 시도할 때 적정한 저온소결특성을 확보하면서도 상변화를 고려한 유리 프리트 첨가량 제어가 필요함을 알 수 있었다.