• KSTLE International Journal
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• v.10 no.1_2
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• pp.23-26
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• 2009

In this work the tribological characteristics were compared between ZnO coatings on glass substrate prepared by sputtering and sol-gel methods. In order to assess the effects of processing method on the tribological characteristics, the friction and wear properties of the coatings were measured by using a reciprocating type of micro-tribotester. The sputtered ZnO coatings were prepared on a glass substrate at room temperature, $150^{\circ}$, and $300^{\circ}$. The ZnO coatings prepared by sol-gel method were heat-treated in air atmosphere at $550^{\circ}$ for one hour. The crystal structure and surface morphology of the coatings were measured by X-ray diffraction (XRD) and Atomic Force Microscope (AFM), respectively. The experimental results showed that overall the sputtered coatings exhibited better friction and wear properties than coatings prepared by sol-gel method. The sputtered coating grown at room temperature had a relatively low friction coefficient of 0.14 and superior wear resistance compared with the other coatings. Nevertheless, sol-gel method of coating ZnO on glass is beneficial for economical coating of a large surface area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• pp.555-558
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• 2004

In this paper, the variable producing conditions of YBCO superconducting powder by use of sol-gel method was investigated. YBCO superconducting powder which was prepared by sol-gel method was shown the characteristic gel formation, particle size and its properties under variable preparation conditions, such as pH, drying and processing time, and powder heat treatment, etc.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1255-1260
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• 2007

[ $TiO_2-V_2O_5$ ] sol was prepared using sol-gel method. Sol changed to gel with hydrolysis and polymerization. DTA properties of gel powder had endothermic reaction due to evaporation of propanol about $80^{\circ}C$, had exothermic reaction due to combustion of propanol about $230^{\circ}C$ and had exothermic reaction due to combustion of alkyl group about $350^{\circ}C$. Crystalline properties of gel powder retained amorphous phase at $50^{\circ}C$, retained anatase phase from $400^{\circ}C\;to\;600^{\circ}C$ and had all rutile phase over $700^{\circ}C$ at 0.01mole $V_2O_5$ additive. The capacitance of thin films increased with increasing heat treatment temperature and thin films had best properties at $700^{\circ}C$. The capacitance of thin films increased a lot with decreasing measurement frequency.

• The korean journal of orthodontics
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• v.36 no.6
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• pp.451-464
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• 2006

The purpose of this study was to search for an appropriate method of coating $TiO_2$ on orthodontic appliances. $TiO_2$ thin films were deposited on orthodontic wires and brackets using sol-gel, CVD (Chemical Vapor Deposition) and PE-CVD (Plasma Enhanced-CVD) methods. The roughness of $TiO_2$-coated surfaces was investigated via scanning electron microscope (SEM) and adhesive strength of $TiO_2$ thin films was measured by adhesive tape pull test. Methylene blue degradation test was carried out to evaluate the photocatalytic activity of $TiO_2$ and the corrosion resistance of $TiO_2$ thin films against fluoride solution was also analyzed by observing the surfaces of $TiO_2$-coated wires and brackets via SEM after immersion in sodium fluoride solution. Through the comparison of properties and photocatalytic activity of $TiO_2$ thin films according to the coating methods, the following results were obtained. Smoother surfaces of $TiO_2$ thin films were generated by CVD or PE-CVD methods than through the sol-gel method or the control. Adhesive strength of the $TiO_2$ thin films was highest in PE-CVD and gradually became lower in the order of CVD, then the sol-gel method. Photocatalytic activity of $TiO_2$ thin films on methylene blue was the highest in PE-CVD and gradually became lower in the order of CVD, then the sol-gel method. Corrosion resistance of $TiO_2$ thin films against fluoride solution was stronger in CVD and PE-CVD methods than in the sol-gel method. The results of this study suggest that the CVD or PE-CVD methods is more appropriate than the sol-gel method for $TiO_2$ coating on orthodontic wires and brackets.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.573-577
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• 2005

[$TiO_2$] sol and $SiO_2$ sol were prepared using sol-gel method. As $H_{2}O$/Alkoxide ratios increased, sol had cluster structure and as $H_{2}O$/Alkoxide ratios decreased, sol had linear structure. Gelation time of $TiO_2$ sol was faster than that of $SiO_2$ sol according to the time. In comparison with initial viscosity between $TiO_2$ sol and $SiO_2$ sol, $TiO_2$ sol was highest at $H_{2}O/Ti(OC_{3}H_{7})_{4}=5$, $SiO_2$ sol was almost constant according to $H_{2}O/Si(OC_{2}H_{5})_{4}$ ratios.

• Journal of Electrochemical Science and Technology
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• v.2 no.2
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• pp.103-109
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• 2011

Nanocrystalline $LiFePO_4$ powders were prepared at 660-$670^{\circ}C$ in an Ar atmosphere using two different synthetic routes, solid-state and sol-gel. Both materials showed well-developed XRD patterns without any impurity peaks. Particles composed in the range of 200-300 nm from the solid-state method, and 50-100 nm from the sol-gel method, were confirmed through scanning electron microscopy and dynamic light scattering. The $LiFePO_4$ obtained by the sol-gel method offered a high discharge capacity (153 mAh/g) and stable discharge behavior, even at elevated temperatures (50 and $60^{\circ}C$), whereas poor electrochemical performance was observed from the solid-state method. Rate capability studies for sol gel-derived $LiFePO_4$ ranged from 0.2 to 30 C, which revealed excellent retention over 70 cycles with a 99.9% capacity.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.3
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• pp.101-106
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• 1999

This research aims to compare immobilized catalysts prepared by various methods and determine suitable $TiO_2$ catalyst for water purification. Sol-gel method by Anderson and powder coation method by Tanaka ate famous in the methods to immobilize catalyst. Therefore, the $TiO_2$ catalyst for this research was prepared by sol-gel method and powder coating method. Its structure was tested by X-ray diffractometer (XRD), Scanning electron microseope (SEM). Durability of a catalyst-support couple in an solution was investigated. too. Experimental results were summarized as following; i) Optimum ratio of Ti : $H_2O$ : $H^+$ to obtain stable sol was 1 : 10 : 0.1 and the XRD patterns of $TiO_2$ film immobilized by sol-gel method which were fired at $700^{\circ}C$ showed that the catalyst had an anatase structure. ii) The particle size of $TiO_2$ prepared by sol-gel method was less than $5{\mu}$, but it was observed that coated side was not unifiom. iii) Sol-gel method was very effective to obtain $TiO_2$ catalyst of thin film, but spreadability and durability of a catalyst-support couple in a solution were than $TiO_2$ film immobilized by powder coating method. iv) The particle size of $TiO_2$ immobilized by powder coating method was a little larger than it prepared by sol-gel method, but spreadability and uniformity of $TiO_2$ film and durability of a catalyst-support couple in a solution were better than it immobilized by sol-gel method.

• Journal of the Korean Ceramic Society
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• v.32 no.9
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• pp.995-1002
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• 1995

The alumina fiber was obtained by extruding the TEA complexed polymeric sol, synthesized by the alkoxide sol-gel method, through nozzle. The purpose of this study was to investigate the properties of fiber spun by TEA complexed sol. The analysis of sol indicated that TEA was bonded at alkoxide precursor and the optimum molar ratio for spinning was 0.5 mole of TEA, 3 mole of H2O. The cross section of the fiber from circular nozzle was not circular but oval, which indicated that the shape of nozzle did not affect the shape of fiber. The diameter of the fiber was about 100 ${\mu}{\textrm}{m}$ in the state of dried gel fiber, 60${\mu}{\textrm}{m}$ in calcined fiber, and the tensile strength of the fiber calcined at 90$0^{\circ}C$ was 2.1$\times$108 Pa.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.865-868
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• 2005

We fabricated the $Pb_{0.72}La_{0.28}TiO_3 (PLT(28))$ thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of 100% perovskite phase by drying at 350$^{\circ}C$ after each coating and final annealing at 650$^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the Pt/Ti/SiO$_2$/Si substrate and its dielectric constant and leakage current density were measured as 936 and 1.1${\mu}$A/cm$^2$, respectively

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1491-1496
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• 2005

We fabricated the $Pb_{0.72}La_{0.28}TiO_3$ (PLT(28)) thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of $100\%$ perovskite phase by drying at $350^{\circ}C$ after each coating and final annealing at $650^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the $Pt/Ti/SiO_2/Si$ substrate and its dielectric constant and leakage current density were measured as 936 and $1.1{\mu}A/cm^2$, respectively.