• 한국세라믹학회지
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• 제36권7호
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• pp.756-761
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• 1999

• 한국결정성장학회지
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• 제8권4호
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• pp.626-633
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• 1998

본 연구에서는 고유전율의 저온소성용 글라스/세라믹을 제조하고자, SiO2-TiO2-RO계 결정화 유리를 제조하고 Al2O3를 필러 물질로 혼합하여 복합체를 제조하고 그 특성을 관찰하였다. 본 유리조성으로써 $900^{\circ}C$ 이하에서 결정화되는 유리의 제조가 가능하였고, RO (BaO, CaO, SrO)의 성분에 따라 결정화 온도는 변화함을 알 수 있었다. 본 유리조성에 $Bi_2O_3$를 플럭스로 첨가하고, 세라믹 필러로써 Al2O3를 사용하여 $860^{\circ}C$에서 소성함으로써 고유전율의 저온소성용 글라스/세라믹의 제조가 가능하였고, 이때 복합체의 밀도는 3.96g/$\textrm{cm}^3$ 이었고, 유전율은 17, Q.f 값은 600이었다.

• 세라미스트
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• 제21권3호
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• pp.216-232
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• 2018

The average life span is over 80 years of age, and various biomaterials have being studied. Many research institutes and companies around the world have been commercializing bioactive glass through R&D, however, there is not much research in Korea. Most bioactive glass is applied to bone regeneration in powder form due to its excellent bio-compatibility. Recently, new applications such as scaffolds for tissue engineering and nerve regeneration have been found in composite form. The global market size is not as large as US $ 556 million in 2019, but the growth rate is very high at a CAGR of 14.35 %. This field is waiting for the challenge of new researchers.

• 한국세라믹학회지
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• 제17권1호
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• pp.27-34
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• 1980

The synthesis of glass-ceramic materials from glasses based on industrial wastes or natural rocks their physical properties were studied. Glasses of composition, CaO14.7∼16.1, MgO7.4∼9.0, Al2O38.3∼19.3, SiO2 48.9∼51.0wt% were prepared from domestic blast furnace slag, serpentine, sea sand and etc. with additions of chromic oxide, and fluoride as nucleating agent. The glasses were subjected to controlled heat treatments and yielded fine microstructure of glass-ceramics which were composed of monocrystalline phase of aluminous diopside. X-ray diffraction techniques were adopted to identify the crystalline phases and to determine the degree of crystallization quantitatively. Density, coefficient of thermal expansion, young's modulus, microhardness and modulus of rupture were measured and the resulting properties were discussed in terms of the heat-treatment conditions, the degree of crystallization, species of crystaline phase, the microstructures formed in glass-cramics and the chemical compositions of mother glasses.

• 한국산업보건학회지
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• 제15권3호
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• pp.213-220
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• 2005

Penetration and health effect of fibers was related with their diameters and length. The purpose of this study is to characterize and compare the diameter and length of airborne man-made mineral fibers(MMMF) or synthetic vitreous fibers in the related industries. The average fiber length of the continuous filament glass, rock wool, refractory ceramic, and glass wool fibers production industries approximately 27, 28, 35, $50-105{\mu}m$. Airborne glass fibers were longest in all the type of MMMFs. The average diameters of airborne fibers generated from refractory ceramic, rock wool, glass wool, continuous filament glass fibers production industries were approximately 1.0, 1.6, 1.5-4 and $10{\mu}m$, respectively. The percentages of respirable fibers(<$3{\mu}m$) were 94% for RCFs, 73% for rock wool fibers, 61.0% for glass fibers, and 1.6% for filament glass fibers. The length of glass fibers were the longest in all types of fibers, and length of the others were similar. The refractory ceramic fibers were smallest in diameters and highest in fraction of respirable fibers.

• 한국세라믹학회지
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• 제54권5호
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• pp.395-399
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• 2017

The thermal properties and crystallization behavior of calcium phosphate glass fabricated using eggshell were examined. Nature eggshell has several impurities in the main component of $CaCO_3$. To manufacture calcium phosphate glass, washed eggshell was dissolved in aqua-regia while adding a solution of isopropyl alcohol, D. I. water and phosphoric acid. The calcined precursor was melted at $1000^{\circ}C$, and the glass ($T_g$ : $540^{\circ}C$) was crystallized at $620{\sim}640^{\circ}C$, which temperature range is relatively low compared to the crystallization temperature of other general types of calcium phosphate glass. The calcium phosphate glass using eggshell was successfully crystallized without any additional nucleating agents due to the multiple effects of impurities such as $Fe_2O_3$, $Al_2O_3$, SrO and $SiO_2$ in the eggshell. The main crystalline phase was ${\beta}-Ca(PO_3)_2$ and a biocompatible material, hydroxyapatite, was also observed. The crystallization process was completed under the condition of a holding time of only 1 h at the low temperature.

• 한국세라믹학회지
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• 제25권1호
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• pp.27-34
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• 1988

In order to investigate the reason of changes in the physical properties of glasses near the region for which R(Ga/Na)=1, spectroscopic studies using FT-IR and Raman spectroscopy have been carried out on Na2O.2SiO2 glass with addition of Ga2O3 from 0 to 35 mole %, i.e., from R=0 to 1.61. The main purpose of this work is to investigate the coordination number of Ga3+ in glass with variation of glass composition and to determine the existence of tricluster in the Ga-rich region for which R>1.0 in Na2O-Ga2O3-SiO2 system.

• 한국세라믹학회지
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• 제39권5호
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• pp.438-445
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• 2002

본 연구에서는 $PbO-TiO_2-SiO_2-BaO-ZnO-Al_2O_3-CaO-B_2O_3-Bi_2O_3-MgO$계의 유리를 $1,400{\circ}C$에서 용융시킨 후, 급랭, 분쇄하여 glass frit을 제조하였다. Glass frit 분말을 일축가압성형한 후 $750~1,000{\circ}C$의 온도범위에서 2시간 동안 소성 및 결정화 하였다. Glass frit의 결정화는 $750{\circ}$ 전후의 온도에서 시작되었고, 저온에서의 주된 결정상은 $Al_2O_3$와 hexagonal celsian($BaAl_2Si_2O_8$)이었다. 소성온도가 높아지면서 monoclinic celsian, $ZnAl_2O_4,\;Zn_2SiO_4,\;CaTi(SiO_4)O,\;TiO_24 등이 주된 결정상으로 나타났고, 특히 celsian은 hexagonal에서 monoclinic으로 상전이가 발생하였다. 그리고 15wt%의 PbO를 첨가한 glass frit에만 $PbTiO_3-CaTiO_3$ 고용체가 나타났다. 1MHz 대역에서 유전특성을 살펴본 결과 유전상수는 11~16이었고, 유전손실은 0.020 미만이었다. 그러나 15wt%의 PbO를 첨가한 glass frit의 경우는 $PbTiO_3-CaTiO_3$ 고용체 결정상의 존재로 유전상수가 17~26으로 높았고, 유전손실은 0.010~0.015로서 다른 조성들에 비하여 우수한 특성을 나타내었다.

• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.35-41
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• 2016

고출력 LED 조명용 패키지를 제조함에 있어서 발열은 LED의 광출력과 수명에 매우 중요한 영향을 주는 인자로 알려져 있다. 본 연구에서는 가로등용 고출력 LED 패키지를 개발함에 있어서 효과적인 방열을 하기 위하여 방열효과가 상대적으로 우수한 구조인 chip-on-a-heat sink 구조를 가지는 세라믹-메탈 기반의 패키지를 제조하였다. 열확산 기능을 하는 heat sink 기판소재는 알루미늄 합금을, LED 어레이 회로를 형성하는 절연막으로는 저온동시소성용 glass-ceramics을 사용하였다. 특히 열처리 시 가장 이슈가 되는 세라믹-금속 하이브리드 패키지 기판의 휨을 억제하기 위한 수단으로서, glass-ceramic 절연막을 부분 코팅함으로써 휨현상을 용이하게 줄일 수 있게 되었다. 또한, LED 패키지의 방열특성의 향상 즉 열저항도 기존의 MCPCB 패키지나 전면 코팅형 절연막 패키지에 비해 훨씬 낮아지는 효과를 얻었을 뿐 아니라, 세라믹 코팅소재의 절감효과도 볼 수 있게 되었다.

• 한국세라믹학회지
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• 제50권3호
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• pp.238-243
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• 2013

We investigated the effect of Pb-metal filler added to a hybrid paste(PbO-$Bi_2O_3-B_2O_3$-ZnO glass frit and Pb-powder), for joining flip-chip sat lower temperatures than normal. The glass transition temperature was detected at $250^{\circ}C$ and the softening point occurred at $330^{\circ}C$. As the temperature increased, the specific density decreased due to the volatility of the Pb-metal and boron component in the glass. When the glass was heat-treated at $350^{\circ}C$ for 5 min, XRD results revealed a crystalline $Pb_4Bi_3B_7O_{19}$ phase that had been initiated by the addition of Pb-filler in the hybrid paste. The addition of the Pb-metal filler caused are action between the Pb-metal and glass that accelerated the formation of the liquid phase. The liquid phase that formed, promoted bonding between the flip-chip substrate sat lower temperature.