• 한국세라믹학회지
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• 제49권2호
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• pp.146-150
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• 2012

The effects of $Al_2O_3$ on the crystallization behavior of glass compositions in the $Na_2O$-CaO-$SiO_2$ system were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effect of $Al_2O_3$ content on the mechanical properties, density, phase formation, and microstructures of $Na_2O$-CaO-$P_2O_5$-$SiO_2$ glass ceramics were studied. The thermal parameters of each glass were studied by DTA. The density of the glass ceramic samples was measured by Archimedes' method. It was found that the glass-ceramic containing 2.0 molar percent $Al_2O_3$ had desirable sintering behavior and reached an acceptable density. Phase investigation and micro-structural analysis were performed by XRD and SEM, respectively.

• 한국세라믹학회지
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• 제33권4호
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• pp.385-390
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• 1996

The electrical resistivity of the ceramic glaze coated on ceramic substrate plays an important role on the characteristics of the thick and thin film electrical circuits. In this study the effects of the various modifiers on the electrical resistivity were examined in SiO2-Al2O3-B2O3-RO-Na2O (RO=CaO , SrO, BaO, PbO) glass system. In alkali free glasses where divalent cations are responsible for electrical conduction the electrical conductivity of th glasses increased with the ionic size of divalent cations due to the decrease in the bond strength between oxyben and divalent cation. In Na2O containing glasses however where Na+ ion is responsible for electrical conduction the ionic conductivity decreased with the ionic size of divalent cations because the blocking effect of the cations on Na+ ion movement increased with larger divalent cations. Na+ ionic conduction also depended on the glass structure relaxation due to the corrdination number changes of B2O3 and Al2O3 which varied with the NaO2 content in the glass.

• 자연과학논문집
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• 제8권2호
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• pp.111-118
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• 1996

$Na_2O$-CaO-$SiO_2$ 계 유리의 화학적 내구성을 향상시키면서 작업점도의 변화를 최소화 하기 위하여, 기본 조성 유리를 선정한 후, 이 조성에 $B_2O_3$, ZnO 성분의 첨가량을 변화시키고 $Na_2O$, $Al_2O_3$, $Li_2O$ 성분을 변화시켜가면서 각 성분이 물성에 미치는 영향을 조사하여 최적 조성비를 얻는 것을 목적으로 하였다. 본 실험결과 $Na_2O$-CaO-$SiO_2$계 유리에서 연화점 변화를 최소화하고 화학적내구성을 극대화 시키는 최적조성(wt%)은 다음과 같았다.$B_2O_3$:3.36%, ZnO:2.88%, $Na_2O$:9.93%, $Al_2O_3$, $Li_2O$:0.19%, $SiO_2$:70.56%, CaO:11.22%, $K_2O$:0.14%

• 한국세라믹학회지
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• 제17권1호
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• pp.20-26
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• 1980

The crystallization behaviors of slag-based glass in $CaO-MgO-Al_2O_3-SiO_2(-Na_2O)$ system have been studied. The mother glass containing 16.50 CaO, 7.50MgO, 19.70Al2O3, 50.80SiO3 and 2.09wt% $Na_2O$ was prepared by using Korean domestic raw materials such as granulated slag, serpentine, sea sand and etc. The glass-ceramics composed of major crystalline phase diopside was produced by the heat treatment in a temperature range from 850$^{\circ}$ to 9$25^{\circ}C$ for 0-6hr. The composition and morphology of diopside phase formed in the system were examined by X-ray diffraction analysis and electron microscopy. The kinetic measurements such as J.M. A plot and Arrhenius plot indicated that the process of nucleation of the initially formed diopside phase could be described from the view point of instantaneous nucleation. It was also demonstrated that the linear crystal growth of diopside phase was proceeded by short range diffusion of $Mg^{2+}$ and $Ca^{2+}$ ion. The microstructures of the resulting glass-ceramics were consisted of leafroidal shaped crystalline aggregations.

• 보존과학회지
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• 제33권3호
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• pp.215-223
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• 2017

익산 미륵사지 석탑의 사리공 내에서 출토된 유리 유물 30점을 분석하여 이들의 성분특성과 상관성, 발색원소 등을 알아보고자 하였으며, 이를 왕궁리 출토 유리의 연구결과와 비교하여 상관관계를 검토하였다. 성분분석 결과, 유리구슬 24점은 $SiO_2$와 $Na_2O$ 성분을 다량 함유한 소다유리군에 속하며, 세부적으로 소다-알루미나유리계 ($Na_2O-Al_2O_3-CaO-Si_2O$)였다. 안정제로서 $Al_2O_3$, CaO, MgO가 첨가된 것으로 보이며, 이를 통해 LCHA(Low CaO, High $Al_2O_3$)형으로 분류할 수 있다. 착색물질은 Ti, Mn, Fe, Cu, Pb 등 성분이 발색에 영향을 준 것으로 판단된다. 나머지 6점은 모두 녹색계열의 유리판 또는 미상의 파편으로 PbO의 함량이 약 70wt.%, $SiO_2$의 함량이 약 30wt.%인 전형적인 $PbO-SiO_2$계의 납유리였다. 이들 유물을 동일 유적권인 왕궁리 출토 유리구슬의 성분과 비교한 결과, 일부 소다유리인 점은 유사하나 $Na_2O$의 함량이 상대적으로 미륵사지 유리 구슬이 매우 높고, 대부분 $K_2O$와 CaO의 함량이 낮다는 점이 다르다. 납유리의 경우도 PbO와 $SiO_2$ 함량이 약간 차이가 있다. 이는 두 유적지에서 제작된 유리 유물이 서로 다른 재료 또는 기술을 이용하였을 가능성도 있는 것으로 보인다.

• 한국세라믹학회지
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• 제33권2호
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• pp.242-250
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• 1996

Glasses of Na2O-Al2O3-SiO2 system were prepared and ion-exchange characteristics change of properties and bactericidal effects by Na+↔Ag+ ion exchange were studied. Parent glasses with three compositions of varying Na2O in the 20~30 wt% were ion-exchanged in the molten salt of 2 mol% AgNO3+98 mol% NaNO3 at 320~36$0^{\circ}C$ for 15~16min. Amount of ion exchange and penetration depth of Ag+ ion increased with Na2O content in the parent glass ion exchange temperature and time. After ion exchange densities and Vickers hardness of the glasses increased and the glasses showed yellow-brown color and as amount of ion exchange increased the color turned deep because partial reduction and agglomeration of Ag+ into Ag0 results in absorption of visible light. After ion exchange chemical durability of the glass to wter was enhanced compara-bly that weight loss and change of surface of the glass were not found for the leaching test in 5$0^{\circ}C$ K.I water for 240hrs. Bactericidal effect of ion exchanged glass on Staphylococcus aureus and E. coli was determined by microorganism test and bactericidal effect increased with amount of ion exchange and incubation time.

• 한국세라믹학회지
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• 제37권2호
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• pp.117-121
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• 2000

Er-doped sodiumborosilicate glass films for waveguides amplifier were fabricated by Aerosol Flame Deposition(AFD) method. Al2O3 was added to sodium borosilicate glass films to suppress the formation of crystalline phase and control the refractive index. the formation of crystalline phase was suppressed above Al2O3 of 6 wt%. As the amount of Al2O3 increased from 2 to 12 wt% the refractive index of glass films increased lineary from 1.4595 up to 1.4710. After the core of 77SiO2-15B2O3-8Na2O＋6 wt%Al2O3＋8wt%Er2O3 was coated on the buffer layer of 77SiO2-15B2O3-8Na2O＋6 wt%Al2O3, the core was etched by reactive ion etching. The absorption spectrum of 3 cm waveguide amplifier showed two peaks of 1530 and 1550 nm.

• 한국세라믹학회지
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• 제36권10호
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• pp.1022-1034
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• 1999

A relation between composition and properties of Na2O-Al2O3-SiO2 glasses was investigated with application of the extreme vertical design. Properties investigated in this study include glass transition temperature density refractive index thermal expansion electrical conductivity bending strength and hardness, Most of the quadratic models fitted on property data were statistically significant. The properties estimated from the fitted equation agreed well with the measured properties. The estimated properties were compared with those reported by other investigators. Additional composition except for those of extreme vertices were needed to yield a slightly better result for the simple system such as a temary system. In addition an optimal composition on each property could be calculated by using optimization technique on result obtained from the fitted quadratic models.

• 한국세라믹학회지
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• 제19권1호
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• pp.13-18
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• 1982

The crystallization of metastable "orthorhombic" phase from the glass in the system of Na $AlSi_3O_8-CaAl_2Si_2O_8$ is studied. These crystals are crystallized in the range of composition from $Ab_80An_20$ to An100. The symmetry of these crystals show orthorhombic as a possible space group P22121. Two probable twin models are proposed. proposed.

• 한국안광학회지
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• 제8권1호
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• pp.1-5
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• 2003

4성분 $Na_2O-B_2O_3-Al_2O_3-SiO_2$ 유리들을 $R({\equiv}Na_2O\;mole%/B_2O_3\;mole%)$과 $K({\equiv}(Al_2O_3\;mole%+SiO_2\;mole%)/B_2O_3mole%)$에 의해 제작하여 유리들의 구조를 굴절률(refractive index)과 vicker's 경도(hardness)의 변화를 측정하여 분석하였다. 먼저, 굴절률의 증가는 유리 내부구조의 분극률을 증가시키는 $Na^+$ 양이온수의 증가에 우선적으로 의존하여 증가하였다. 적은 양의 소듐 산화물($Na_2O$) 이 첨가된 영역에서 굴절률은 소듐 이온 양에 의존하였으며, 많은 양의 소듐 산화물이 첨가된 영역에서는 큰 몰 부피를 갖고 하나의 비가교 산소를 갖는 $BO_3{^-}$ 단위들의 형성으로 유리 구조 내의몰 부피 증가로 유리들의 굴절률의 증가가 둔화되었다. 그리고 알루미늄 산화물($Al_2O_3$)과 규소 산화물($SiO_2$)의 증가에 따라 굴절률의 감소는 $Al_2O_3$와 $SiO_2$에 의해 형성되어진 $AlO_4$ 단위들과 $SiO_4{^-}$ 단위들이 붕소 산화물($B_2O_3$)에 의해 형성되어진 $BO_4$ 단위들보다 몰 부피의 증가로 감소되어졌다. 또한, 경도의 증가는 유리 망목구조에 형성되어지는 $BO_4$ 단위 수에 의존하였으며, 경도의 감소는 유리 망목구조를 개방화시키는 $BO_3{^-}$ 단위 수에 의존하여 감소함을 알 수 있었다.