• 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.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.139-144
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• 2004

In the present study, a simple method was successfully used for hydroxyapatite coatings on Ti-6Al-4V substrates deposited by using a sol-gel derived precursor. Prior to hydroxyapatite coating the samples were micropolished (0.1 micron) and divided into three sets. The first set,were the micropolished samples kept as such. The second set were coated with titania sol and the third set was treated with 5M NaOH. After three repetitions of hydroxyapatite coating procedures on each set and heat treatment at 600 $^{\circ}\Delta C$, the formation of hydroxyapatite has been confirmed by XRD analyses and the substrate material was found to be oxidized with negligible amount of CaO in the coating. The SEM studies revealed surface morphology. Hydroxyapatite, calcined at 600$^{\circ}\Delta C$, displaying a porous structure arisen from heating of the bulk. But, it is very meaningful in trying to approach morale management plans with an object of dental technicians. It is necessary that dental technicians should make efforts to control themselves.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.89-96
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• 1997

In order to apply synthesis technique of the high purity ceramic powder to the traditional ceramic powder, mullite powder which is widly used for refractory materials was synthesized. Boehmite and Hadong kaolin with high alumina content were used as starting materials and gel coating method was tried to produce the mullite powder. As a result, the mullite powder of high quality was successfully obtained at 1350℃. The unreacted silica and cornudum were not observed in the synthesized mullite powder, mullite content was more than 80% when the starting materials were sintered at 1700℃. Their properties showed bulk specific gravity of 2.56, water absorption of 1.9%, and 3-point flexual strength of 169 MPa. It is thought that that their good properties are applicable to refractory materials of high quality.

• The Journal of Engineering Research
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• v.6 no.1
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• pp.161-168
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• 2004

In the present study, a simple method was successfully used for hydroxyapatite coatings on Ti-6AL-4V substrates deposited by using a sol-gel derived precursor. Prior to hydroxyapatite coating the samples were micropolished (0.1 micron) and divided into three sets. The first set, were the micropolished samples kept as such. The second set were coated with titania sol and the third set was treated with 5M NaOH. After three repetitions of hydroxyapatite coating procedures on each set and heat treatment at $600^{\circ}C$, the formation of hydroxyapatite has been confirmed by XRD analyses and the substrate material was found to be oxidized with negligible amount of CaO in the coating. The SEM studies revealed surface morphology. Hydroxyapatite, calcined at $600^{\circ}C$, displaying a porous structure arisen from heating of the bulk

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1271-1282
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• 1994

The surface of commercial alumina fibers used for reinforcing the MCFC matrix has been coated with ${\gamma}$-LiAlO2 being the same material as the matrix, by the sol-gel method in order to enhance the corrosion resistivity of alumina fibers. Stable LiAlO2 complex polymeric sols for coating was synthesized by mixing aluminum alkoxide polymeric sols with LiNO3 solution. It was found that the LiAlO2 polymeric sol prepared by adding the mixed chelate of acethylacetone and triethanolamine (the mole ratio of AA/TEA = 0.125/0.75) to the 1 mole of the aluminum alkoxide had the excellent stability and coating behavior. The crystalline structure of the dried gel from the ${\gamma}$-LiAlO2 sol was completely transformed into the ${\gamma}$-LiAlO2 at $600^{\circ}C$. The optimum viscosity of the sol for coating the alumina long fibers was 30~40 cP, while it was 12~20 cP in case of the short fiber coating. The ${\gamma}$-LiAlO2 coated alumina fibers without defects fully densified when heat-treated at 120$0^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.2
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• pp.93-98
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• 1983

Apple sugaring and apple nectar gel were treated with coating agent, and then the rate of weight loss, browning reaction and fungi growth on the storage conditions of those were investigated. The results obtained were summarized as follows; The composition of sucrose, D-sorbitol, corn syrup, gelatin, arabia gum, citric acid, sodium citrate and sodium ascorbate as a nontoxic coating agent was desirable to repress weight loss browning reaction and fungi growth of apple sugaring and apple nectar gel. It was the most effective method that apple sugaring was treated with the coating agent and refrigerated with double packaging. The contraction by weight loss, browning reaction and fungi growth of apple nectar gel treated with the coating agent and freezed with double packaging were repressed.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.725-728
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• 2002

A series of fabric filters including P-84, Nomex and PTFE were coated with a commercial $V_2O_5/TiO_2$ catalyst as an effort to develop a functional fabric filter of simultaneous removal of dust and NOx. The coating methods employed are sol-gel coating method, spray coating method and dip coating method, and the effects of coating method on NOx removal performance of functional fabric filter were investigated. Experimental conditions are as follows: the temperatures of $100-250^{\circ}C$ which are the normal operating temperature range of fabric filters, the space velocity of $5,000hr^{-1}$, the oxygen concentration of 6%, and the $NH_3/NO$ ratio of 1.0. Results showed that the sol-gel coating method gave the best NOx removal performance mainly due to its ability in controlling the amount of catalyst and uniform coating.

• Polymer(Korea)
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• v.31 no.6
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• pp.485-490
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• 2007

Hard coating was made on a polycarbonate plate using a sol-gel process with a melamine derivative and silicates, and examined as potential substitutes for automobile glass. Methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and phenyltriethoxysilane were used to form a coating solution. The coatings on the polycarbonate plate were deposited using a sol-gel process. Poly(methyl methacrylate) was coated on the surface of polycarbonate in order to improve adhesion property. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Adding the melamine derivative to the coating solution, the pencil hardness of the coating was improved. The hardness of a 3H class pencil, excellent abrasion resistance, and surface uniformity were found in the coated polycarbonate surface.

• Journal of the Korean Ceramic Society
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• v.29 no.3
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• pp.216-222
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• 1992

PLZT thin films were prepared using sol-gel spin coating. The films mainly consisted of perovskite phase when heat treated at 600$^{\circ}C$ and in O2 or air atmosphere for 2 hours after 7 coating cycles. Cracks were formed when smaller than after 9 coating cycles. When ITO interlayer existed between Corning 7059 glass substrate and the film, cracks were not formed after 9 coating cycles, but cracks were formed after 11 coating cycles because of large volume change of the film contracting on the substrate during the heat treatment. In the observation of microstructure, the thin films have perovskite phase of about 2 $\mu\textrm{m}$ grain size and pyrochlore phase of 100∼200${\AA}$ grain size.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.806-809
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• 2009

Epoxy functionalized organic-inorganic hybrid materials (hybrimers) were synthesized by sol-gel reaction for application in OLED barrier coating. By using the calcium degradation method, the oxygen transition rate (OTR) and water vapor transition rate (WVTR) measured so far is $10^{-2}cc/m^2$-day for oxygen and $10^{-1}g/m^2$-day for water molecules with single hybrimer coating film, respectively. Encapsulated OLED devices have life time of 14hrs of a single hybrimer barrier coating and 29hrs of hybrimer/inorganic double barrier coatings at $25^{\circ}C$ and 60% relative humidity.