• Korean Journal of Materials Research
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• v.34 no.7
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• pp.355-362
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• 2024

AR (alkali resistant)-glass fibers were developed to provide better alkali resistance, but there is currently no research on AR-glass fiber manufacturing. In this study, we fabricated glass fiber from AR-glass using a continuous spinning process with 40 wt% refused coal ore. To confirm the melting properties of the marble glass, raw material was put into a (platinum) Pt crucible and melted at temperatures up to 1,650 ℃ for 2 h and then annealed. To confirm the transparent clear marble glass, visible transmittance was measured and the fiber spinning condition was investigated by high temperature viscosity measurement. A change in diameter was observed according to winding speed in the range of 100 to 700 rpm. We also checked the change in diameter as a function of fiberizing temperature in the range of 1,240 to 1,340 ℃. As winding speed increased at constant temperature, fiber diameter tended to decrease. However, at fiberizing temperature at constant winding speed, fiber diameter tended to increase. The properties of the prepared spinning fibers were confirmed by optical microscope, tensile strength, modulus and alkali-resistance tests.

• 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.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.150-150
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• 2002

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.112-115
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• 2005

The objectives of this study are to evaluate the dynamic fracture toughness of advance glass ceramics(MACOR glass-filled ceramic, Corning Glass Works) for dome port cover of the ramjet. Static and dynamic fracture toughness tests are performed using strain gage method in the variation of notch radii.

• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.30-34
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• 2009

A Sand blasting technology has been used to address via and trench processing of glass wafer of optic semiconductor packaging. Manufactured sand blast that is controlled by blast nozzle and servomotor so that 8" wafer processing may be available. 10mm sq test device manufactured by Dry Film Resist (DFR) pattern process on 8" glass wafer of $500{\mu}m's$ thickness. Based on particle pressure and the wafer transfer speed, etch rate, mask erosion, and vertical trench slope have been analyzed. Perfect 500 um tooling has been performed at 0.3 MPa pressure and 100 rpm wafer speed. It is particle pressure that influence in processing depth and the transfer speed did not influence.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.335-342
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• 1987

There were several numbers of studies on chemically strengthening glass. Most of them were strengthened in molten salt bath below transformation range of glass. Apart from them, this study used solution hydration technique by Autoclave. After determining proper concentration of AgNO3 salt solution, experimental condition varied from 4hrs to 16hrs at relatively low temperature (180, 200, 220$^{\circ}C$). The results showed that the Soda-Lime-Silica glass could be strengthened by diffusion mechanism without influence of water above 15% salt solution. Because of Ag+ ion penetration in glass surface, yellow color appeared and decreased transmittance at visible range. Modulus of rupture was increased with the amount of exchange and brittleness was decreased.

• Journal of the Korean Ceramic Society
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• v.17 no.4
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• pp.213-216
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• 1980

A glass-ceramics material of composition %SiO_2$: 38.50, $Al_2O_3$: 26.00, $Na_2O$: 18.00, CaO: 6.00, MgO: 4.00, $TiO_2$: 7.50 was strengthened by coating a series of glazes$(SiO_2-B_2O_3-Al_2O_3-CaO-PbO-Na_2O-)$, which has lower thermal expansion coefficient than that of the glass-ceramics. The thermal expansion coefficient of the glazes ranges $80~90{\times}10^{-7}$cm/cm/$^{\circ}C$, whereas that of the glass-ceramics is $115{\times}10^{-7}$cm/cm/$^{\circ}C$. The glass-ceramics was identified to be composed of nepheline, carnegieite low form, and meta sodium silicate crystal by X-ray diffraction phase analysis. The glaze, having lower melting point and appropriate thermal expansion coefficient, was tried to be stable and good at secondary heat treatment.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.236-242
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• 1993

As the fundamental research on preparation of fine single crystalline ferroxaplana by means of glass-crystallization methods using steel twin-roller, the properties of ferroxplana crystallized from glass were studied. Most of the specimens quenched by twin-roller at about 130$0^{\circ}C$ were glass phase, the crystallization of these glasses underwent multi-steps and ferroxplana phase was only stable in the temperature range of 88$0^{\circ}C$ to 95$0^{\circ}C$. Above 95$0^{\circ}C$ ferroxplana begines to be decomposed in glass. Ferroxplana had such magnetic properties as M8=29emu/g, MHC=166Oe, and Curie Temperature, Tc=610$\pm$5K.

• Journal of the Korean Ceramic Society
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• v.30 no.6
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• pp.485-491
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• 1993

Porous glass in the ZrO2.SiO2 system containning up to 30mol% zirconia were prepared by the sol-gel method from metal alkoxides and their pore characteristics with reaction parameters were investigated. The gels were made by hydrolyzing and condensation of the mixed metla alkoxides and were converted into the porous glass by heating up to $700^{\circ}C$. As a results, the mean pore radius became larger with increasing contents of HCl, H2O and hydrolysis temperature, and an alcohol with a large molecular weight for making the porous glass. In the case of 20ZrO2.80SiO2 porous glass with heated at $700^{\circ}C$, HCl and H2O content was 0.3mol and 4mol, the specific surface area was 284$m^2$/g, average mean pore radius was about 19.4$\AA$, porosity was 22.55% and pore characteristics depended on heating temperature.

• The Korean Journal of Ceramics
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• v.1 no.3
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• pp.131-136
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• 1995

It has been reported that the biocement obtained by mixing $CaO-SiO_2-P_2O_5$ glass powders with ammonium phosphate solution has biocompatibility as will as high strength. The hardening mechanism and hydroxyapatite forming mechanism were discussed when $53.6%CaO_1,\; 38.1%SiO_2,\; 7.7P_2O_6,\; 0.6%CaF_2$(mole %) glass powder was reacted with ammonium phosphate solution and reacted in tris-buffer solution, respectively. High strength hardened biocement was obtained for the specimen with $CaNH_4PO_4\;H_2O$ crystal when the glass powder was mixed with ammonium phosphate solution, and hydroxyapatite crystal was rapidly formed only in the sample with $CaNH_4PO_4\;H_2O$ crystal when it was reacted in tris-buffer solution.