• Korean Journal of Materials Research
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• v.12 no.7
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• pp.545-549
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• 2002

Potassium-Calcium-Phosphate glasses in range $XCaO\cdot(50-X)K_2O$ \cdot $50P_2$$O^{5}$were investigated. Glass transition temperature(Tg) of prepared glasses were below $520^{\circ}C$, thermal expansion coefficient from $270.3$\times$10^{7}$ to $604.5$\times$10^{7}$/$^{\circ}C$. The structure of XCaO.(50-X)$K_2$O\cdot$50P_2$$O^{5}$ glasses were examined by FT-IR spectroscopy indirectly. As CaO was increased, Ts, Tg, P-O-P bonding strength and chemical durability were increased. Glass surface change was observed with increasing dissolution time using bulk specimen, weight loss and pH change were measured as function of the dissolution time.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.84.1-84.1
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.107.1-107
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• 2002

• Restorative Dentistry and Endodontics
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• v.44 no.3
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• pp.24.1-24.1
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• 2019

• Journal of the Korean Ceramic Society
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• v.37 no.9
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• pp.900-908
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• 2000

일반적인 유리용융과 열처리법을 이용하여 많은 양의 금속구리 미립자가 분산된 Zinc Phosphate 유리를 제조하였다. 금속산화물로는 Cu$_2$O를, 환원제로는 SnO를 사용하였다. XRD와 전자회절로부터 열처리에 의해 금속구리의 결정상이 석출됨을 알 수 있었고, TEM에 의해 석출상의 크기는 수~20nm 정도임을 알 수 있었다. 또한 570nm에서의 광흡수 피크로부터도 금속구리의 석출을 확인할 수 있었다. 석출입자의 크기와 흡광은 석출을 위한 열처리 온도와 시간이 증가함에 따라 증가하였다. XPS 스펙트럼으로는 구리의 산화상태 중 Cu$^{2+}$ 이온의 상태만을 분명히 할 수 있었다. 매질유리의 BO/NBO의 비는 열처리 전후 크게 변화가 없었으며, 열처리 후 Cu$^{2+}$ 이온이 다소 감소되는 경향을 보였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.266-273
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• 2011

Foamed glass was fabricated by using glass powder and foaming agents. For the glass powder, we used sodalime glass which's manufactured by using refused coal ore obtained as by-product from Dogye coal mine in Samcheok. And for the foaming agents, we used Calcium carbonate, Calcium phosphate and powder of shale type refused coal ore itself which has high content of carbon materials. We additionally used liquid binder for forming, and mixed together. And we formed rectangular shape and treated $800^{\circ}C$ for 20 min in an electrical furnace. The various kinds of foam glass samples were fabricated according to the kinds of foaming agents. The physical properties of samples, as specific gravity and compressive strength, were measured. Pore structure of each samples were investigated too. Foam glass with specific gravity of 0.4~0.7 and compressive strength of 30~72 kg/$cm^2$. Especially we get satisfying foam glass sample with low specific gravity of 0.47 and high compressive strength of 72 kg/$cm^2$ by the use of liquid calcium phosphate as foaming agent. It also had small and even shape of pore structure. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a foamed glass panel for construction and industrial materials.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.410-418
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• 2000

An in vitro study was performed to evaluate the effect of four variables on the temperature rise produced by polishing of restorations. The four variables were : restorative material, base, thickness of remaining dentin, continuous polishing or intermittent polishing. Class V cavities were cut on extracted molar and restored with composite resin, resin-modified glass ionomer cement, compomer, amalgam on the various bases (glass ionomer cement, zinc oxide eugenol cement, zinc phosphate cement) Dentin thickness under the restoration was 0.5mm, 1.5mm. Polishing was done with an aluminum oxide-coated disc. Polishing time was continuous or intermittent for up to 1 minute. Intra-pulpal temperature increased almost linearly in all cases. Amalgam produced highest temperature rises at the pulp, while the composite resin, resin-modified glass ionomer cement and compomer were not different for each other. The rate and extent of temperature rising of amalgam restoration was reduced by presence of a cement base. Zinc oxide eugenol cement bases showed the highest temperature rise, while glass ionomer cement, zinc phosphate cement were not different to the untreated tooth Thickness of remaining dentin was only significant for the amalgam restoration. Continuous polishing produced higher temperature rise than intermittent polishing.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.17-22
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• 2004

In this study, BNT($BaO-Nd_{2}O_3-TiO_2$) and $70P_{2}O_5-5B_{2}O_3-(25-x)BaO-xNa_{2}O$ glass-ceramic composites were fabricated and investigated in order to apply for low temperature cofired ceramic. The prepared BNT based glass-ceramic composites were sintered at $800{\sim}950^{\circ}C$ with the glass fit contents ranging from 10 to $15\;wt\%$. The properties such as sintering and dielectric property were investigated in the ceramic compositions according to the phosphate glass frit. The dielectric constant was varied between 10 to 40 and shrinkage rate was increased according to increasing glass frit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3286-3291
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• 2014

A study on the crack protection and thermal insulation properties of the expanded perlite inorganic composites was performed. Mixed expanded perlite with a water glass was stabilized for 24 hrs at room temperature in the mold and, thereafter, converted into a massive foamed body through complete drying process at $150^{\circ}C$. Aluminum phosphate and micron size mica powder were used as a reaction accelerator and a stabilizer for thermal crack, respectively. Especially, use of mica exhibited a remarkable effect on the protection of thermal crack at higher temperature over $500^{\circ}C$, and thermal conductivity of the composites was enhanced with higher perlite contents, showing ca. 0.09 W/mK for the sample of 100/200/10/1.5 water glass/perlite/mica/Al phosphate by weight. A severe dimensional deformation of the composite materials was observed over $600^{\circ}C$, however, showing a temperature limitation for a practical application. The facts were considered as the results from the glass transition temperature of the water glass, of which main component is sodium silicate.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.39-45
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• 2008

Titanium and its alloys are widely used as dental implants materials because of their excellent mechanical properties. However, the alumina and zirconia ceramics are preferred to use as the substitute of Ti implants because there is a problems in esthetics and biocompatibility in Ti implant. The the glass infiltrated alumina ceramics are studied to increase the toughness and biocompatibility. The 45S5 and soda-lime glass powder was mixed with ethanol at ratio of 1:1 and brushed on the surface of alumina. Then it was heat treated in the electric furnace at $1400^{\circ}C$ from 30 min. to 5 hours. The glass powder was controlled from 200 to $350{\mu}m$ using ball milling. After heat treatment, the glass infiltrated specimen was tested in universal testing machine to measure the bending strength. The surface microstructure of each specimen was observed with SEM. The biocompatibility of 45S5 and soda-lime glass coated alumina was investigated using PBS at $36.5^{\circ}C$ incubator. The specimen was immersed in PBS for 3, 5, 7, 10 days. After that, the surface morphology was investigated with SEM. As the results of experiment, the 45S5 bioglass infiltrated alumina show the increase of bending strength according to the increasing of heat treatment time from 30 min. to 5 hours at $1400^{\circ}C$ Finally the 1370N bending strength of alumina increased to 1958N at 5 hours heat treatment, which shows 1.4 times higher. In contrast to this, the soda lime glass infiltrated alumina ceramics shows the convex curve according to heat treatment time. Thus it shows maximum bending strength of 1820N at 1 hour heat treatment of $1400^{\circ}C$ It gives 1.3 times higher. However, the bending strength of soda lime glass infiltrated alumina is decreasing with increasing heat treatment time after 1 hour. The precipitation on the surface of 45S5 glass infiltrated alumina was revealed as a sodium phosphate ($Na_{6}P_{6}O_{24}6H_{2}O$) and the amount of precipitation is increasing with increasing of immersion time in PBS. In contrast to this, there is no precipitation are observed on the surface of soda lime glass infiltrated alumina. This implies that 45S5 glass infiltrated alumina brings more biocompatible when it is implanted in human body.