• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.158-160
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• 2001

본 연구는 레이저 처리기술에 의한 Li$_2$O-A1$_2$O$_3$-SiO$_2$계 유리의 미세가공과 레이저에 의한 유리의 광활성반응에 관한 것으로서, 1064nm와 355nm의 파장을 갖는 Nd:YAG laser를 유리에 조사하여 유리의 파괴특성 및 광학적변화를 관찰하였다. 1064nm 레이저에 의한 유리의 파괴 부분은 광학현미경과 주사전자현미경(SEM)으로서 파괴특성을 평가하였으며, 355nm 레이저에 의한 유리의 변화는 흡수대역을 측정함으로 그 광학적 특성을 나타내었다. 이와 같은 레이저에 의한 가공은 유리내부의 3차원적인 미세구조물 형성이나, internal waveguide, 또는 광 흡수대역의 변화에 따른 광기록방법으로 응용될 것으로 예상된다.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.43-46
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• 2000

Nd:YAG laser of 355 nm wavelength, which amounts to 3.5 eV, produced by a harmonic generator was used to create Ag metallic particles as seeds for nucleation in photosensitive glass containing $Ag^+$ and $Ce^{3+}$ . The pulse widths and frequency of the laser were 8ns and 10 Hz, respectively. For crystalline growth, heat-treatment following laser irradiation was carried out at $570^{\circ}C$ for 1h. Then, the $LiAlSi_3O^8$ crystal phase appeared in the laser irradiated lithium aluminum silicate glass. We present the effect of laser-induced nucleation compared with spontaneous nucleation by heat treatment fur crystallization in the glass.

• Journal of the Korean Ceramic Society
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• v.30 no.7
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• pp.535-542
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• 1993

It was investigated in this study that a preparation method, activation energy, surface area, pore volume, pore size distribution and DTA analysis of the dry gel in process of producing monolithic porous gel in Li2O-Al2O3-TiO2-SiO2 system by the sol-gel technique using metal alkoxides. Activation energy for gellation according to the variation of water concentration and the kind of catalysts ranged from 10 to 20kcal/mole. Monolithic dry gels were prepared after drying at 9$0^{\circ}C$ when the amount of water for gellation was 4~8 times more than the stoichiometric amount, that was necessary for the full hydrolysis of the mixed metal alkoxide. The specific surface area, the pore volume, the average pore radius of the dried gel at 18$0^{\circ}C$ according to the various kinds of catalyst were about 348~734$m^2$/g, 0.35~0.70ml/g and 10~35$\AA$, respectively. It showed that the dry gels were porous body. As a result ofthe analysis of DTA, it was confirmed that the exothermaic peaks at 715$^{\circ}C$ and 77$0^{\circ}C$ was clue to the crystallization of dried gel.

• Journal of the Korean institute of surface engineering
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• v.25 no.5
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• pp.215-221
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• 1992

This research is aimed at developing(110) preferred TiS2 cathode films and glass typed solid electro-lytes which have high ionic migrations and low electron conductivities for thin secondary solid batteries. To obtain preferred oriented TiS2 thin films on a substrate by CVD method using TiCl4 and H2S gases three factors of heating temperature, inner pressure of furnace and TiCl4/H2S gas mole fraction were ex-amined systematically. To obtain solid films of Li2O-B2O3-SiO2 electrolytes by r.f. sputtering for thin proto-type batteries of Li/Li2O-B2O3-SiO2TiS2, sputtering conditions were examined. TiS2 cathode films showed columnar structure, namely c axis oriented parallely. At low pressure of reaction chamber and low heating temperature, surface of smooth TiS2 films couldd be obtained. Ionic conductivity of Li2O-B2O3-SiO2 films manufactured by r.f. magnetron sputtering were 3$\times$10-7$\Omega$-1cm-1 and electron conductivities were 10-11$\Omega$-1cm-1. Open cell voltage of thin lithium batteries were 2.32V with a designed prototype cell.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.127-127
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• 1994

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.4
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• pp.154-159
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• 2019

The glass-ceramic of $Li_2O-Al_2O_3-SiO_2$ system was fabricated by using yttrium oxide and iron oxide that it can reduce the melting temperature and affect the homogenization. Zirconium sulfate was used as a nucleation agent. Calcium phosphate was used to improve the flow the glass so as reduce the viscosity of the glass. The glass-ceramics met a thermal shock test of more than $750^{\circ}C$ and the temperature at which the coefficient of thermal expansion rapidly increased at over $800^{\circ}C$ was shifted by about the above $30^{\circ}C$. Therefore, it is concluded that the glass-ceramic of $Li_2O-Al_2O_3-SiO_2$ system with yttrium oxide and iron oxide was founded to have good melting conditions and excellent thermal expansion resistance at high temperature such as special field for kitchen utensils.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.118.2-118.2
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• 2007

• Journal of the Korean Ceramic Society
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• v.14 no.4
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• pp.230-235
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• 1977

In this paper the conditions of surface crystallization of glass were studied. The basic glass which is apt to crystallize, with $SiO_2$ 72.50, $Al_2O_3$ 5, 00, $Na_2O$ 8.00 $K_2O$ 3.50, CaO 5.00, MgO 3.00, $B_2O_3$ 3.00 Wt% is chosen. The strain point and softening point of this glass is 4$25^{\circ}C$ and 778$^{\circ}C$ each, and between the two temperatures we could get grystal on its surface by immersion in salt baths during some controlled hours. The kind of crystal on the surface of glass was confirmed by X-ray diffraction analysis and the change of the thickness of crystalline layers depending on temperature and time, was surveyed by using optical microscope. The results are as follows; 1. The chloride group is more suitable than sulfate group for the treating salt. 2. In the condition with 50 LiCl.50NaCl at 62$0^{\circ}C$ for 2 hrs and with 50 LiCL.20-30 NaCl.30-20 $CaCl_2$ at 72$0^{\circ}C$ for 15-20 min. we could get the best crystalline layers. 3. The crystal was silica-O and petalite with a little tridymite and nepheline. 4. The thickness of crystalline layers increased with increasement of temperature and time.

• 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 Ceramic Society
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• v.33 no.2
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• pp.192-202
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• 1996

In Li0.4Ca0.05AlP0.5Si0.75O4.5 composition glass, glass-ceramic having a near 100% crystallinity after nucleation heat treatment of 74$0^{\circ}C$/2 h and crystallization heat treatment of 90$0^{\circ}C$/2 h and in-situ TiO2 whisker reinforced glass-ceramic after heat treatment of 105$0^{\circ}C$ for 20 h were fabricated with the addition of 4% TiO2 as a nucleating agent. With these materials a ball-on-disc type wear test was conducted in order to examine the effect of TiO2 whisker prepcipitation on ambient and high temperature wear properties of the glass-ceramic. Wear test results indicated that all specimens exhibited micro-fracture wear mechanism in ambient temperature. As temperature increased the wear rates of the materials were increased. However the in-situ TiO2 whisker reinforced glass-ceramic exhibited the lowest wear rate over the test temperature range. This resulted from the improvement of harness and fracture toughness of the material as the glass converted into the glass-ceramic followed by precipitation of TiO2 whiskers throughout the glass-ceramic matrix.