• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.66-72
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• 2020

The difference of plasma resistance between the CAS glass bulk and coating films were compared. Plasma resistance was confirmed by analyzing the etch rate and the microstructure of the surface when the CAS glass bulk and the glass coating film were etched with CF₄/O₂/Ar plasma gas. CAS glass coating film was etched up to 25 times faster than the glass bulk. A statistically high correlation between the surface roughness and the etching rate of the coating film was derived, and thus, the high surface roughness of the coating film was determined to cause rapid etching. In addition, cristobalite crystals that has a low Ca content and a high Si content, was foamed on the glass coating film. Therefore, the CAS glass coating film is considered to have low plasma resistance compared to the glass bulk.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.593-596
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• 1999

This paper presents a process optimization of antireflectiun (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a doble-layer AR(DLAR) coating of MgF$_2$/CeO$_2$, We investigated CeO$_2$ films as an All layer because they hale a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ film deposited at 400 $^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04 % in the wavelengths ranged from 0.4 7m to 1.1 7m. We achieved the efficiencies of solar cells greater than 15% with 3.12 % improvement with DLAR coatings . Further details on MgF$_2$, CeO$_2$ films, and cell fabrication Parameters are presented in this paper.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.447-450
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• 2003

This paper presents a process optimization of antireflection (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a double-layer AR (DLAR) coating of MgF$_2$/CeO$_2$. We investigated CeO$_2$ films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ deposited at 40$0^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04% in the wavelengths ranged from 0.4${\mu}{\textrm}{m}$ to 1.1${\mu}{\textrm}{m}$. We achieved the efficiencies of solar cells greater than 15% with 3.12% improvement with DLAR coatings. Further details on MgF$_2$, CeO$_2$ films, and cell fabrication parameters are presented in this paper.

• Journal of the Korean institute of surface engineering
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• v.43 no.5
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• pp.238-242
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• 2010

In the present work, the influence of oxide on the Cr-Si-N coatings was investigated for the Cr-Si-O-N coatings on AISI 304 and Si wafer deposited by hybrid system, which combines the DC magnetron sputtering technique and arc ion plating (AIP) using Cr and Si target in an $Ar/N_2/O_2$ gaseous mixture. As the O content in the Cr-Si-N coatings increased, the diffraction patterns of the Cr-Si-O-N coatings showed CrN and $Cr_2O_3$ phases. However, as the O content increased to 28.8 at.%, diffraction peak of $Cr_2O_3$ was disappeared in the Cr-Si-O-N coating. The $d_{200}$ value was decreased with increasing of O content. The average grain size increased from about 40 nm to 65 nm as the O content increased. The maximum micro-hardness of the Cr-Si-O-N coating was obtained 4507 Hk at the O content of 24.8 at.%. The average friction coefficient of the Cr-Si-O-N coatings was gradually decreased by increasing the O content and the average friction coefficient decreased from 0.37 to 0.25 by increasing the O content. These results indicated that amorphous phase was increased in the Cr-Si-O-N coatings by increasing of O content.

• Journal of Korea Foundry Society
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• v.5 no.3
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• pp.19-26
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• 1985

This study has been carried out to examine into wettability of Cu-5%Sn alloy in $Al_2O_3$, MgO, $SiO_2$ and graphite, respectively and investigated into the change in macrostructure of Cu-5%Sn alloy according to kind and mixing rate of mold-coating. The results obtained from the experiment are summerized as follows; 1. Cu Cu-5%Sn alloy, wettabilities of $Al_2O_3$ and MgO were good, on the other hand, wettabilities of $SiO_2$ and graphite were bad. 2. The fine equiaxed zone was created because of the role of $Al_2O_3$ and MgO as preferential nucleation sites. 3. Notwithstanding change of mixing rate of $SiO_2$ in mold coating the equixed zone was not created. 4. The area of equiaxed zone was varied according to mixing rate in the case of using $Al_2O_3$ and MgO in mold-coating.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.63-70
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• 1995

A crack-free ceramic composite membrane with micropores has been synthesized by the pressurized sol-gel coating technique using the mixed Al2O3-SiO2 sols. The mixed sols were prepared by mixing nanoparticulate SiO2 and boehmite sols. These sols were more stable at lower pH, but very unstable when their copositions were in the range of 50~75mol% of SiO2 at the same pH. The mixed Al2O3-SiO2 membrane prepared from the mixed sol (0.2mol/$\ell$ of solid content and pH=2) containing 40mol% of SiO2 had the mean pore radius of 0.80nm and the specific surface area of 280$m^2$/g. The nitrogen permeability through the coated Al2O3-SiO2 layer was 42$\times$107mol/$m^2$.s.Pa. It was found that the thermal stability of aluminosilicate membranes, even through similar to that of SiO2 membranes, was much improved in comparison with ${\gamma}$-alumina membranes.

• Bulletin of the Korean Chemical Society
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• v.17 no.7
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• pp.621-625
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• 1996

A variety of metal oxides were coated by sol-gel process from their metal alkoxides on the ribbons of Co-based and Fe-based amorphous alloys, and the effects of surface oxide coating on the magnetic properties of the alloy are investigated. The core loss is found to be reduced significantly by the oxide coating, the loss reduction becoming more prominent at higher frequencies. The shape of the hystersis loop is also dependent upon the kind of the coated metal oxide. The coatings of MgO, SiO2, MgO·SiO2 and MgO·Al2O3 induce tensile stress into the Fe-based ribbon whereas those of BaO, Al2O3, CaO·Al2O3, SrO·Al2O3 and BaO·Al2O3 induce compressive stress. These results may be explained by the modification of domain structures via magnetoelastic interactions with the shrinkage stress induced by the sol-gel coating.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.7-11
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• 2000

The anti-reflective anti-static (ARAS) optical film is designed using absorbent materials such as ITO, $TiN_xW_y$, Ag by Essential Macleod program. [air ${\mid}TiN_xW_y{\mid}SiO_2{\mid}$ glass] two layer shows wide-band AR coating in the wavelength range of 450~700 nm. The reflectivity, transmittance of this coating are below 0.5%, about 75%, respectively. [air $SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$, ITO glass] layer can adjust reflectance of below 0.5% with above 97% transmittance. In the [air ${\mid}SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$ Ag glass] layer, the transmission can be controlled at above 96% with reflectance of 1~2%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.298-307
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• 2019

Two types of CaO-Al₂O₃-SiO₂ (CAS) glass powder applied spray coating on the surface of sintered Al₂O₃ were researched for sintering behavior; (1) Si-rich, glass containing high content SiO₂, (2) Ca-rich, containing high content CaO. Foaming of bubbles remaining inside the Ca-rich glass was produced at a viscosity of approximately 10⁷~10⁹ poise, resulting in decreasing shrinkage (interfering with sintering) and increasing surface roughness. In case of Si-rich glass, there was no serious foaming bubbles phenomenon like Ca-rich below 1000℃, however cristobalite crystals with low density occurred at 1200℃ and then produced re-foaming of bubbles, resulting in abnormal sintering behavior. These phenomenon is considered to be a decrease in viscosity due to an increase in the Ca content of the glass according to the formation of low-density cristobalite crystals. Therefore, in case of CAS glass, it is necessary to consider the increase of surface roughness and the sintering interference because of foaming bubbles phenomenon at low temperature sintering. Especially, when containing high SiO₂ content, abnormal foaming phenomenon due to crystallization at high temperature should be predicted.

• Journal of the Korean Ceramic Society
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• v.32 no.8
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• pp.909-914
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• 1995

From alumina powder and TEOS, $\alpha$-Al2O3/SiO2 composite powder for reaction-sintered mullite was synthesized by heterogeneous coagulation and surface coating, and investigated the mullitization reaction and sintering behavor of these powders. In $\alpha$-Al2O3/SiO2 composite powder prepared by heterogeneous coagulation, each alumina particles were surrounded by silica particles of 50~60 nm in size. And the alumina particles in composite powder prepared by surface coating were coated by uniform silica layer with thickness of 50 nm. In both methods, mullitization reaction was completed at 1$650^{\circ}C$ for 3h, and specimen sintered above 145$0^{\circ}C$ was about 95% fo the theoretical relative density. Mullite grains formed from the reaction with composite powders showed spherical shape with a size of 1~2${\mu}{\textrm}{m}$.