• Journal of the Korean Society of Industry Convergence
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• v.10 no.3
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• pp.179-185
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• 2007

Quartz glass are used in semiconductor industries as the reaction furnace, wafer carrier and accessaries. During the process the quartz glass received compression by direct contact with other quartz glass ware and metal as the form of weight itself and vacuum pressure and fatigue by vibrations caused by process. Even as the other ceramic materials quartz glass have high compressive strength but often there happened crack and breakage of quartz glass resulted in a great damage in the process. In this paper investigation will be carried out on fracture behavior of quartz glass under local load to give guideline to prevent unintended fracture of quartz glass.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.350-357
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• 2006

A new valveless micropump for bi-directional application has been developed and tested. The micropump was fabricated on silicon and glass substrates by micromachining process. The micropump in this study consists of a membrane actuator, a pumping chamber, fluidic channels and two piezoelectric ceramic films. The channels and pumping chamber were etched on a glass wafer and the membrane was made on a silion wafer which is actuated by a piezoelectric ceramic (PZT) film. The geometry of the micropump was optimized by numerical analysis and the performance of the micropump was investigated by the experiments. The maximum flow rate was $323{\mu}L/min$ and the maximum back pressure was 294 Pa when the membrane actuator of $10{\times}10mm^2$ was driven at 130 Hz and 385 V.

• Journal of Ceramic Processing Research
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• v.21 no.2
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• pp.213-216
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• 2020

We investigated the optimal conditions for the manufacture of a rapid SiC heating element with increased durability for a flipchip bonder. In the moulding step prior to the sintering of the SiC heating element, a pressure of either 25 or 125 MPa wasapplied by uniaxial pressing to control the micropores; this was aimed at improving the resistance of the ultimate specimen. The moulded specimen was sintered by using a vacuum furnace with silicon as a sintering additive. The measurement of thehot modulus of rupture (HMOR) of the resulting SiC sintered body revealed that the HMOR was high. In addition, a methodfor protecting the heating element from the external environment was developed. A glassy coating layer was deposited on thesurface of the structure to improve the corrosion resistance of the sintered body; further, the performance of the coating layerwas verified through a neutral and acidic salt spray test. Finally, we established the optimal process conditions formanufacturing a rapid SiC heating element with improved corrosion resistance.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.939-944
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• 1998

The formation microstructure and properties of novel ceramic composite materials by active filler con-trolled polymer pyrolysis were investigated. Polymethlsiloxane filled with W is of particular interested be-cause of the formation of ceramic bonded hard materials (WC-$W_{2}C$-$S_{1}OC$) for wear resistant applications. Highly metal-filled polymer suspensions were prepared and their conversion to ceramic composites by an-nealing in $N_{2}C$ atmosphere at 1000-$1600^{\circ}C$ were studied. Dimensional change porosity and phase distribution (filler network) were analyzed and correlated to the resulting material properties. Microcrystalline com-posites with the filler reaction products embedded to the resulting material properties. Microcrystalline com-posites with the filler reaction products embedded in a silicon oxycarbide glass matrix were produced. De-pending on the pyrolysis conditions ceramic composites with a density up to 95 TD% a hardness of 7-8.8GPa Yong's modulus of 220-230 GPa a fracture toughness of 6-6.8$MPam^{1/2}$ and a flexual strength of 380-470 MPa were obtained.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.6
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• pp.641-658
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• 2001

All-ceramic restorations have become an attractive alternative to porcelain-fused-to-metal crowns. In-Ceram, and more recently IPS Empress 2 were introduced as a new all-ceramic system for single crowns and 3-unit fixed partial dentures. But their strength and marginal fit are still an important issue. This study evaluated the fracture resistance and marginal fit of three systems of 3 unit all-ceramic bridge fabricated on prepared maxillary anterior resin teeth in vitro. The 3 all-ceramic bridge systems were: (1) a glass-infiltrated, sintered alumina system (In-Ceram) fabricated conventionally, (2) the same system with copy-milled alumina cores (copy-milled In-Ceram), (3) a heat pressed, lithium disilicate reinforced glass-ceramic system (IPS Empress 2). Ten bridges of each system with standardized design of framework were fabricated. All specimens of each system were compressed at $55^{\circ}$ at the palatal surface of pontic until catastrophic fracture occurred. Another seven bridges of each system were fabricated with standard method. All of the bridge-die complexes were embedded in epoxy resin and sectioned buccolingually and mesiodistally. The absolute marginal discrepancy was measured with stereomicroscope at ${\times}50$ power. The following results were obtained: 1. There was no significant difference in the fracture strength among the 3 systems studied. 2. The Weibull modulus of copy-milled In-Ceram was higher than that of In-Ceram and IPS Empress 2 bridges. 3. Copy-milled In-Ceram($112{\mu}m$) exhibited significantly greater marginal discrepancy than In Ceram ($97{\mu}m$), and IPS Empress 2 ($94{\mu}m$) at P=0.05. 4. The lingual surfaces of the ceramic crowns showed smaller marginal discrepancies than mesial and distal points. There was no significant difference between teeth (incisor, canine) at P=0.05. 5. All-ceramic bridges of three systems appeared to exhibit sufficient initial strength and accept able marginal fit values to allow clinical application.

• Journal of the Korean Ceramic Society
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• v.18 no.1
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• pp.13-22
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• 1981

This study is to investigate the effective mineralizer in the manufacture of forsterite porcelain as a high frequency insulator. A mixture of $Mg(OH)_2$. and $SiO_2$.($\alpha$-Quartz) corresponding to the molar ratio of 2.0 MgO: 1.0 $SiO_2$ was prepared from the materials of high purity. It was heated to 140$0^{\circ}C$ at the rate of 20$0^{\circ}C$/hr, which was kept constantly for 1 hour, and one has made chamotte after cooling. Six kinds of glasses were prepared by an 0.1 atomic equivalent of K ions substitution-Ba, Bi, Zn, Cd, Zr-to the basic K-glass (0.333 $K_2O$.1.14 $SiO_2$) and were melted approximately at 150$0^{\circ}C$. The forsterite bodies were provided by adding each glass (10, 15, 20, 25, 30%) to the forsterite chamotte, which was fired at 1320, 1360, 1400, 144$0^{\circ}C$. (1 hr). One has examined the physical and dielectric properties for the specimens. The results of the experiments are as follows; 1. As for water absorption: Bodies were better vitrified with an addition and temperature change of Ba, Bi, Zn-glasses. The specimen containing Cd-glass showed deviation of slow decreasing, where as K-glass was completely not vitrified. 2. Bodies containing Ba, Zn, Bi-glasses appeared comparatively high Modulus of Rupture at 136$0^{\circ}C$, while containing Zr-glass had the highest Modulus of Rupture as the addition changes remarkably at 140$0^{\circ}C$. 3. It was estimated that 20-25% glass present in a forsterite bodies were in good conditions as for physical properties. 4. Specimens of Ba, Bi, Zr-glasses were superior as for dielectric properties, where among Ba-glass was most excellent. 5. Dielectric constant commonly increases in a slight gradient as firing temperature rises. 6. The petrographic examination showed that the bodies containing Ba, Bi-glasses had fine crystals, and were observed distinctly large mosaic crystals in the Zn-glass.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.57-61
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• 2016

Thick film sealing glass paste is required for cell packaging of NaS based battery for energy storage system, to join the beta-alumina electrolyte tube and the alpha-alumina battery cell cap components. This paper presents the effect of the particle sizes of seal glass powder and the sealing temperatures on the microstructure of the glass sealants was investigated. It was found that the larger in the particle size of seal glass powder, the smaller the pore volume and the number of pores in a unit area. Also, the number of pores decreased with increasing the sealing temperatures while the pore size was increased. This result enables the control of porosity, pore distribution and number of pores in a microstructure of glass sealing component by proper selection of glass powders particle size and sealing temperature.

• Journal of the Korean Ceramic Society
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• v.26 no.6
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• pp.771-782
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• 1989

Synthesis of $\beta$-Sialon powder was attempted with carbothermal reduction of porous glass. The porous glass was prepared by heat and hydrothermal treatments of 9.32 Li2O.46.5B2O3.37.2SiO2.6.98Al2O3 glass. Carbon pyrolyzed from propane gas was deposited on the porous glass, thereafter activated carbon was added as reducing agents. The synthesized $\beta$-Sialon powder was pressureless sintered at 175$0^{\circ}C$ for 1hr in N2 atmosphere. The characterization of the $\beta$-Sialon powder was performed with XRD, BET, SEM and particle size analysis. The sinterability and mechanical properties of the sintered bodies were investigated in terms of bulk density, M.O.R., fracture toughness, morphology of microstructure and etc. The reduction effect of deposited carbon was better than that of activated carbon mechanically added. The formation of SiC was precominant over that of Si2ON2 and $\beta$-Sialon owing to low partial pressure of N2 inside the pore, wehreas on the surface of porous glass the formation of Si2ON2 and $\beta$-Sialon were predominant. Thereafter, SiC reduced unreacted glass to be $\beta$-Sialon. Single phase of $\beta$-Sialon(Z=1.92) was obtained from PGA porous glass having the largest pore radius by the simultaneous reduction and nitridation method at 145$0^{\circ}C$ for 5hrs. The bulk density, M.O.R., and KIC of the sitered body are 3.17g/cc, 434.4MPa and 4.1MPa.m1/2, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.455-463
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• 2022

As the need for R&D for high reliability cameras, such as satellite cameras, increases, the reliability of the bonding strength properties between an opto-mechanical structure and an optical component has been secured through specimen tests. However, the widely used specimen shape is not suitable for the application of glass and glass-ceramic material, which is fragile, making it difficult to obtain accurate bonding properties due to stress concentration in glass parts before reaching the bonding strength limit. In this study, the stress distribution characteristics in the shear test condition for various specimen shapes were studied analytically, based on the test results of the glass material's own fracture. Through this, the shape characteristics capable of relieving the stress concentration of the glass part were derived, and the range of the bonding shear strength verifiable by the specimen test was improved.

• Ceramist
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• v.10 no.3
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• pp.48-54
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• 2007

Glass-ceramics transparent above $10\;{\mu}m$ in the infrared, have been synthesized. They are based on germanium and antimony sulphides or selenides associated to alkali halides. They are prepared by heating glass samples at temperatures above the glass transition, as a function of time. Ceramisation can be controlled, so that sub-100 nm crystals are generated in the glass matrix. Then, low light scattering is achieved and the transparency window of the original glass is maintained. When gallium sulphide is added, glass ceramics can be doped with rare-earth ions. Emissions from the $^4F_{3/2}$ and $^4I_{13/2}$ of $Nd^{3+}$ and $Er^{3+}$ ions, respectively, are more intense in glass-ceramics, as compared to their vitreous counterpart. Examination of band profiles and decaytimes show that rare-earth ions are embedded in both crystalline and glassy environments.