• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.3
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• pp.103-106
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• 2022

The effect of Al₂O₃ on isokom temperatures in soda-lime glass is estimated by comparing calculated isokom temperatures using viscosity model proposed by Lakatos. Substitution of SiO₂ with Al₂O₃ by 0.5 mol% raises the isokom temperatures by 3.1, 3.3, 3.6 and 7.2℃ at the viscosity of log η = 12.3, 10, 6.6 and 1 (Pa·s), respectively. Meanwhile, replacing 0.5 mol% of CaO with Al₂O₃ raises the isokom temperatures by 1.6, 2.3, 4.1 and 17.7℃ at the viscosity of log η = 12.3, 10, 6.6 and 1 (Pa·s), respectively.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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• pp.939-945
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• 2004

Glasses of $SiO_2-B_{2}O_3-Al_{2}O_3-CaO-La_{2}O_3$ with various amounts of $La_{2}O_3$ were infiltrated into a porous alumina to make an alumina-glass composite. The infiltration characterization and bending strength of the composite were examined in terms of glass composition. $La_{2}O_3$ in the glass decreased the high temperature viscosity and this enhanced the wetting behaviour of this glass to alumina, and made glass infiltration easier. The infiltrated glass dissolved the alumina skeleton, and $Al_{2}O_3$ component in the glass melt reprecipitated on the alumina. The grain growth occurred to a specific crystal direction. The glass containing $20mole\%$ of $La_{2}O_3$ was crystallized after infiltration, and this enhanced the bending strength of the composite.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.272-273
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• 2006

LTCC(low temperature co-fired ceramics)용 glass/ceramic 복합체를 제조하기 위해 4 종류의 borosilicate계 glass를 선정하고 filler로 $Al_2O_3$ ceramics를 filler 사용하여 30~50 vol% glass frit에 따른 소결 및 유전 특성에 대하여 조사하였다. Glass frit은 $SiO_2$와 $B_2O_3$ 함량비를 고정한 후 R(CaO, BaO, ZnO, $Bi_2O_3$)에 따라 유리 연화온도(Ts)와 함량이 소결에 미치는 영향 및 유전 특성 변화를 고찰한 결과, CaO-$B_2O_3-SiO_2$ glass의 경우 다량의 2 차상이 형성되었고, 이에 $900^{\circ}C$ 이하에서 완전 소결이 이루어지지 않았으며, BaO-$B_2O_3-SiO_2$ glass는 celsian($BaAl_2Si_2O_8$) 결정이 형성되면서 소결성의 저하를 갖고 왔으며, ZnO-$B_2O_3-SiO_2$ glass는 소결이 진행됨에 따라 주상이 $Al_2O_3$에서 gahnite($ZnAl_2O_4$) 결정이 형성되면서 품질계수가 크게 증가하였으며, $Bi_2O_3-B_2O_3-SiO_2$ glass는 45 vol%일 때 $900^{\circ}C$에서부터 일정한 선수축율 특성을 나타내었지만, 다량의 액상으로 인하여 유전 특성의 저하를 나타내었다.

• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.114-118
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• 2015

$V_2O_5-P_2O_5-ZnO-Sb_2O_3$ glasses modified with BaO and $Al_2O_3$ are synthesized as a sealing material for large-scale dye-sensitized solar cells (DSSCs). A compositional study is performed in order to determine the glass that can be sintered below $500^{\circ}C$ with a high chemical stability against the electrolyte. The flow size of the glasses after the heat treatment and the glass stability are increased with the addition of $Al_2O_3$ and BaO, while the glass transition temperature is decreased. After the reaction with the electrolyte at $60^{\circ}C$ for 72 h, the addition of 5 mol% of BaO and 2 mol% of $Al_2O_3$ considerably enhances the chemical stability of the glass. X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to examine the reaction between the electrolyte and glasses. The structural contribution of the additives is also investigated and discussed.

• Journal of Powder Materials
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• v.25 no.5
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• pp.426-434
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• 2018

In this study, $MgO-CaO-Al_2O_3-SiO_2$ (MCAS) nanocomposite glass powder having a mean particle size of 50 nm and a specific surface area of $40m^2/g$ is used as a sintering additive for AlN ceramics. Densification behaviors and thermal properties of AlN with 5 wt% MCAS nano-glass additive are investigated. Dilatometric analysis and isothermal sintering of AlN-5wt% MCAS compact demonstrates that the shrinkage of the AlN specimen increases significantly above $1,300^{\circ}C$ via liquid phase sintering of MCAS additive, and complete densification could be achieved after sintering at $1,600^{\circ}C$, which is a reduction in sintering temperature by $200^{\circ}C$ compared to conventional $AlN-Y_2O_3$ systems. The MCAS glass phase is satisfactorily distributed between AlN particles after sintering at $1,600^{\circ}C$, existing as an amorphous secondary phase. The AlN specimen attained a thermal conductivity of $82.6W/m{\cdot}K$ at $1,600^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.22 no.2
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• pp.3-10
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• 1985

In the study the characteristics change of crystallized $Li_2O$.$Al_2O_3$.$SiO_2$ glass-ceramics when varying RO ratio and increasing Al2O3 were investigated to produce a glass-ceramics with high mechanical strength and low thermal expansion. Parent glass was obtained by melting at 1,350~1,40$0^{\circ}C$ for 3 hours and annealing at 45$0^{\circ}C$ and the various physical characteristics were measured. Results were as follows; 1. When ZnO was replaced by MgO thermal expansion coefficient was lowered when increasing ZnO content. 2. Major crystal phase was $\beta$-spodumene the crystal growth mophology was the three dimensional sphere and the activation energy for crystallization was 54.6 Kcal/mol. 3. Parent glass heat-treated at 95$0^{\circ}C$ for 10 hours had ; a) thermal expansion coeff. of $23.2{\times}10^{-7}$/$^{\circ}C$ b)whiteness of 76 c) microhardness of 1,089kg/$mm^2$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.323-323
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• 2007

Influence of $La_2O_3$ addition to $CaO-B_2O_3$-based glass on the water leaching resistance of the glass was first investigated. The optimized $La_2O_3-CaO-B_2O_3$(LCB) glass was ball milled for varying time, followed by mixing with $Al_2O_3$ crystalline phase to form $Al_2O_3$-LCB glass composites at $875^{\circ}C$ for 1h. Microwave dielectric properties of the composites were investigated as a function of the ball milling time of the LCB glass. Dielectric constant and quality factor of the composites were 6.31 and 13856 GHz, respectively, when the LCB glass was ball milled for 2h prior to mixing with $Al_2O_3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.324-324
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• 2007

Influence of $La_2O_3$ addition to $ZnO-B_2O_3$-based glass on the water leaching resistance of the glass was first investigated. The optimized $La_2O_3-ZnO-B_2O_3$ (LZB) glass was ball milled for varying time, followed by mixing with $Al_2O_3$ crystalline phase to form $Al_2O_3$-LZB glass composites at $875^{\circ}C$ for lh. Microwave dielectric properties of the composites were investigated as a function of the ball milling time of the LZB glass. Dielectric constant and quality factor of the composites were 6.01 and 11676 GHz, respectively, when the LZB glass was ball milled for 2h prior to mixing with $Al_2O_3$.

• Journal of Powder Materials
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• v.27 no.6
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• pp.498-502
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• 2020

We investigate the effects of Yb2O3 and calcium aluminosilicate (CAS) glass as sintering additives on the sintering behavior of AlN. The AlN specimens are sintered at temperatures between 1700℃ and 1900℃ for 2 h in a nitrogen atmosphere. When the Yb2O3 content is low (within 3 wt.%), an isolated shape of secondary phase is observed at the AlN grain boundary. In contrast, when 3 wt.% Yb2O3 and 1 wt.% CAS glass are added, a continuous secondary phase is formed at the AlN grain boundary. The thermal conductivity decreases when the CAS glass is added, but the sintering density does not decrease. In particular, when 10 wt.% Yb2O3 and 1 wt.% CAS glass are added to AlN, the flexural strength is the highest, at 463 MPa. These results are considered to be influenced by changes in the microstructure of the secondary phase of AlN.

• Journal of the Korean Ceramic Society
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• v.36 no.12
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• pp.1350-1355
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• 1999

Sintering characteristics and dielectric properties of low temperature sinterable Glass/Ceramic dielectric materials were investigated. The dielectric materials which were developed for microwave frequency applications consist of SiO2-TiO2-Bi2O3-RO system(RO:BaO-CaO-SrO) crystallizable glass and Al2O3 as a ceramic filler. Sintering experiments showed that no more densification occurred above 80$0^{\circ}C$ and bulk density and shrinkage depended on Al2O3 content only. Results of dielectric measurements showed that $\varepsilon$r Q$\times$f and $\tau$f of the material containing 30wt% Al2O3 were 17.3, 600 and +23 ppm respectively. Those values for 45 and 60wt% Al2O3 samples were 11.6, 1400, +0.7 ppm and 7.2, 2000, -8.5 ppm, repectively. The results clearly showed that the Glas/Ceramic materials of present experiment decreased in $\varepsilon$r and increased in $\times$f value and changed from positive to negative value in $\tau$f value with the increasement of Al2O3 content.