• Journal of the Korean Ceramic Society
• /
• v.17 no.3
• /
• pp.151-157
• /
• 1980

Crystallization phenomena of glasses of fused natural basalt rocks were studied by DTA, X-ray phase analysis, electron microscopy, and other techniques. Crystallization was catalyzed by the addition of either chromite ore or $P_2O_5$, both up to 5 wt %. Various heat treatments were used, and their influences on controlling the microstructures and properties of the products were studied to develop high strength glass-ceramic material of the $CaO-Al_2O_3(Fe_2O_3)-MgO(FeO)-SiO_2$ system from the domestic basalts. Magnetite precipitates were found to be a nucleation initiator in every case of the crystallization. Diopside, anorthite, clinoenstatite and monticellite were identified as silicate crystalline phases contained in the crystallized products. The crystallite size was in the range of 0.1-2.5$\mu\textrm{m}$. The fine crystallites were approximately cubic, but large crystallites were either plate or needle shape. The thermal expansion coefficient, microhardness and modulus of rupture of glass-ceramics were ranged from 78.5 to 81.8$\times$10-7 cm/cm/$^{\circ}C$, from 820 to 930kg/$\textrm{mm}^2$, and from 1800 to 2800kg/$\textrm{cm}^2$, respectively.

• The Journal of Korean Academy of Prosthodontics
• /
• v.34 no.1
• /
• pp.169-186
• /
• 1996

The purpose of this study was to investigate the mechanical properities and biocompatibility with crystallization temperature and time of a bioactive glass-ceramic system $41.4wt%SiO_{2}-35.0wt%CaO-3.0wt%MgO-12.0wt%P_{2}O_{5}-8.6wt%Al_{2}O_{3}$ with same molar percent of $Al_{2}O_{3}\;and\;P_{2}O_{5}$. The crystallization behaviors were investigated with DTA, XRD and SEM. Fracture toughness with the change of crystallization temperature and time was measured by indentation fracture method. Also, biocompatibility was evaluated by culture of mouse fibroblast cell line L929. The results obtained were as follows ; 1. The major crystalline phases were apatite and anorthite, and relative intensity of anorthite phase was increased at $1004^{\circ}C$. 2. The hardness and fracture toughness were gradually increased with the increase in ceraming temperature to $1004^{\circ}C$. 3. When the glass ceramic was heat-treated for 4 hours at ceraming temperature of $1004^{\circ}C$, hardness and fracture toughness showed the maximum values $578.84k/mm^2\;and\;2.07MPa\;m^{1/2}$, respectively. 4. The growth rate and cytotoxic of L929 fibroblast cells for bioactive glass ceramic were better than those of stainless steel and titanium.

• Korean Journal of Materials Research
• /
• v.12 no.12
• /
• pp.924-929
• /
• 2002

To recycle waste materials, this work was focused on development of glass-ceramic from incinerator fly ash with a large content of Cl and its physical property was evaluated. In the process, water washing as a pre-treatment before melting the fly ash was used to remove large amount of Cl component in the ash and to reduce melting temperature. As a result, glass was obtained at below $100^{\circ}C$ compared to the melting temperature before washing the ash. Also, internal crystallization occurred under single stage heat treatment (at $850-950^{\circ}C$ for 20-340min) without adding other materials into the ash. It was shown that the glass-ceramic was composed of four crystals, diopside, anorthite, akermanite, and unknown phase. Hardness of 8.3GPa was found in the glass-ceramic, which is a high value compared to reported others. Thus, the present process suggests that a good glass-ceramic produced from an incinerator ash could be applicable for structural materials in terms of economic and environmental points.

• Journal of the Korean Ceramic Society
• /
• v.20 no.1
• /
• pp.25-30
• /
• 1983

This experiment was studied in the system of (1-x) CaO MgO $2SiO-Al_2O_3$ to investigate forming of solid solution. The technique empolyed was the well known water-quenching method. Differential thermal analysis of the each glass water quenched indicated that under 30 mole% $Al_2O_3$ was lowered with increasing of the amount of $Al_2O_3$ It was supposed by X-ray diffraction patterns of each specimen sintered at various temperature that only solid solution was formed under the 30mole % $Al_2O_3$ compositions solid solution and anorthite were formed at the 20mole% $Al_2O_3$ composition anorthite solid solution and spinel$(MgAl_2O_4)$ were formed over the 40mole% $Al_2O_3$ compositions. The maximum density and thermal expanison coefficient was 2.89g/cm 7.74x106./C$^{\circ}$ respectively in the composi-tion of 10 mole% $Al_2O_3$ . All the specimens showed linear thermal expansion behavior. Microhardness was as high as 850kg/nm2 in the composition of 5, 10, 20 mole % $Al_2O_3$ and dielectric constant was 7.3-6.9.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.309-309
• /
• 2007

The LTCCs (low-temperature co-fired ceramics) are very important for electronic industry to build smaller RF modules and to fulfill the necessity for miniaturization of devices in wireless communication industry. The dielectric materials with sintering temperature $T_{sint}$<$900^{\circ}C$ are required. In this study, we investigated with glass-ceramic composition, which was crystallized with two crystals. The microstructure, crystal phases, thermal and mechanical properties, and dielectric properties of the composites were investigated using FE-SEM, XRD, TG-DTA, 4-point bending strength test and LCR measurement. The starting temperature for densification of a sintered body was at $779{\sim}844^{\circ}C$ and the glass frits were formatted to the crystal phases, $CaAl_2Si_2O_8$(anorthite) and $CaMgSi_O_6$(diopside), at sintering temperature. The sintered bodies exhibited applicable dielectric properties, namely 6-9 for ${\varepsilon}_r$. The results suggest that the glass-ceramic composite would be potentially possible to application of low dielectric L TCC materials.

• Electrical & Electronic Materials
• /
• v.8 no.1
• /
• pp.95-101
• /
• 1995

Crystallizable glasses with precipitation of celsian, anorthite, wollastonite and gahnite were prepared for the purpose of insulating dielectric layers in devices such as integrated circuit substrates. The starting glasses were prepared by melting the batches for 1 hour at 1450.deg. C and then Quenching to a distilled water. And crystallization behavior of these glasses were studied by DTA, TMA, XRD analysis and by the measurement of dielectric properties. The overall composition of the glass-ceramic consists in weight percent of 30-35% A1$_{2}$O$_{3}$, 13-26% BaO, 5-21% CaO, 10-24% ZnO, 4.5-9.0% TiO$_{2}$ and 4-8% B$_{2}$O$_{3}$. As a result, in barium-rich glasses only celsian phase was developed in the range of 850-900.deg. C. Also, the thermal expansion coefficient, dielectric constant and quality factor of these glass-ceramics were 68*10$^{-7}$ /.deg. C, about 9 and more than 1000, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.208-208
• /
• 2008

Micro patterning of conductor line/space on LTCC green sheet in the LTCC module is an important process for miniaturization in 3D integrated circuits. This work presented the effect of inorganic binders on the microstructure, adhesion, electrical resistivity, shrinkage and line/space resolution, which is a part of study in photoimageable conductor paste. The photoimageable conductor paste contains silver powder, polymer binder, monomer, photo-initiator, UV absorber, and solvent. The inorganic binders were furnished with varied weight percentage of anorthite, diopside and MLS-62 glass frits from 0% to 7%. The Line/space sizes thus obtained was under 25 micron.

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.1
• /
• pp.61-69
• /
• 2015

While the macroscopic properties and eruption style of basaltic and phonolitic melts are different, the microscopic origins including atomic structures are not well understood. Here we report the atomic structure differences of glass in diopside-anorthite eutectic composition (basaltic glass) and phonolitic glass using high-resolution 1D and 2D solid-state Nuclear Magnetic Resonance (NMR). The $^{27}Al$ MAS NMR spectra for basaltic glass and phonolitic glass show that the full width at half maximum (FWHM) of Al for basaltic glass is about twice than phonolitic glass, suggesting the topological disorder of basaltic magma is larger than that of phonolitic magma. The $^{27}Al$ 3QMAS NMR spectra for basaltic glass and phonolite glass show much improved resolution than the 1D MAS NMR, resolving Al and Al. Approximately 3.3% of Al is observed for basaltic glass, demonstrating the configurational disorder of basaltic magma is larger than phonolitic magma. This result confirms that the topological disorder of Al in basaltic glass is larger than that of phonolitic glass. The observed structural differences between basaltic glass and phonolitic glass can provide an atomistic origin for change of the macroscopic properties with composition including viscosity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.195-195
• /
• 2008

CAS계 유리에 $CaCO_3-Al_2O_3$ 혼합물 및 화합물을 10, 30 wt% 첨가하여 저온 소걸 및 마이크로파 유전 특성을 고찰하였다. CAS계 유리의 연화온도는 $841^{\circ}C$ 이며, CAS계 유리에 $CaCO_3$ 와 30 wt%의 $CaCO_3-Al_2O_3$ 혼합물을 melting되며, 10 wt%의 $CaCO_3$, $Al_2O_3$, $1CaCO_3-1Al_2O_3$ 혼합물 및 $CaAl_2O_4$ 화합물를 10 wt% 첨가하였을 때 $900^{\circ}C$ 이하에서 소걸이 가능하였다. 복합체의 XRD 상 분석 결과, CaCO3를 첨가하였을 때에는 모든 조성이 비정질을 나타내었고, $Al_2O_3$와 $1CaCO_3-1Al_2O_3$ 혼합물은 $Al_2O_3$ 결정상이 생성되었고, $CaAl_2O_4$ 화합물은 $CaAl_2Si_2O_8$의 hexagonal와 anorthite 결정상이 생성되었다. 따라서 CAS-10 (A, C-A, CA) 복합체는 $900^{\circ}C$에서 각각 유전율 ($\varepsilon_r$) 6.4, 6.9, 5.15 와 품질계수 ($Q^*f$) 2,400, 1,500, 3,000의 마이크로파 유전 특성을 나타내어 LTCC 기판 재료로 사용이 가능하며, 특히 $CaAl_2O_4$ 화합물을 사용하였을 때 가장 우수한 유전 특성을 나타내는 것을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.61-61
• /
• 2008

이동 통신의 급격한 발전에 따라 이동통신 기기의 부품들이 소형화되고 다양한 기능이 요구되어지고 있다. 이동 통신용 부품은 패턴의 미세화와 비아 수의 증가 등 고집적화로 인한 강도 요구로 LTCC 소재의 사용이 증가되고 있다. 또한 glass의 조성이 결정상 생성 및 복합체의 미세 구조에 영향을 미칠 것으로 기대되지만 유리의 조성에 관한 연구는 아직 미비하다. 본 연구에서는, anorthite를 생성시키는 LTCC composite용 glass에서 융점 및 Tg에 영향을 주는 것으로 알려진 B와 Zn의 양을 변화시키고 2가 금속(Mg, Sr, Ba)원소를 첨가함에 따라 compostite에서 아노사이트 상을 비롯한 결정상의 생성과 이에 따른 미세구조의 변화를 살펴 보았다. 조성변화에 따라 제조된 glass는 Tg를 측정하고, 제조된 glass를 $Al_2O_3$ filler와 혼합하여 tape casting 공정으로 시트를 제작하였다. 제조된 시트를 소결한 후에, 강도, 유전 특성, 밀도를 측정하였다. 소결체는 미세구조와 상분석을 통해 LTCC 소재와 글래스 조성과의 상관관계를 확인하고자 하였다.