• 한국세라믹학회지
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• 제45권1호
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• pp.36-42
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• 2008

Carbon/$TiO_2$ composite photocatalysts were thermally synthesized with different mixing ratios of anatase to phenol resin through an ethanol solvent dissolving method. The XRD patterns revealed that only anatase phase can be identified for Carbon/$TiO_2$ composites. The diffraction peaks of carbon were not observed, however, due to the low carbon content on the $TiO_2$ surfaces and the low crystallinity of amorphous carbon. The results of chemical elemental analyses of the Carbon/$TiO_2$ composites showed that most of the spectra for these samples gave stronger peaks for carbon and Ti metal than that of any other elements. The BET surface area increases to the maximum value of $488\;m^2/g$ with the area depending on the amount of phenol resin. From the SEM images, small $TiO_2$ particles were homogeneously distributed to a composite cluster with the porosity of phenol resin-based carbon. From the photocatalytic results, the MB degradation should be attributed to the three kinds of synergetic effects, such as photocatalysis, adsorptivity, and electron transfer by light absorption between supporter $TiO_2$ and carbon.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.123-125
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• 2006

The $TiO_2$ sol was prepared hydrothermally in an autoclave from aqueous $TiOCl_2$ solutions as a starting precursor. Hollow fibers were obtained when the sol-gel-derived $TiO_2$ sol was treated chemically with a NaOH solution and subsequently heated in the autoclave under various conditions. A systematic analysis of the influence of different NaOH concentrations on the formation of nanotubes was carried out. The details of the nanotubular structure were investigated by using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). From the TEM images, the outer and the inner diameters of the tubes were measured to be about 8 and 4 nm, respectively, the lengths were measured to be several hundreds of nanometers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.39-42
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• 2006

Titania sols or powders were are very promising materials for environment as photocatalyst. The band gap energy of $TiO_2$ has been known to be 2.8 to 3.2 eV. But the measuring system of its band gap is usually depend on absorption properties. Thus, in this study, absorption properties of $TiO_2$ sols prepared by hydrothermal process were researched with the effect of various particle sizes and concentrations. The mean particle size in $TiO_2$ sols increased as 15 nm to 60 nm, absorption graph measured by UV-Vis spectrometer shows to move red-shift. When dilute solution added with $2^n$ in $TiO_2$, the band gap energy increases as linear function.

• 한국분말재료학회지
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• 제17권6호
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• pp.449-455
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• 2010

The hybrid structured photo-electrode for dye-sensitized solar cells was fabricated based on the composites of $TiO_2$ nanoparticles and nanowires. Three samples with different hybrid structures were prepared with 17 vol%, 43 vol%, and 100 vol% nanowires. The energy conversion efficiency was enhanced from 5.54% for pure nanoparticle cells to 6.01% for the hybrid structure with 17 vol% nanowires. For the hybrid structured layers with high nanowires concentration (43 vol% and 100 vol%), the efficiency decreased with the nanowire concentration, because of the decrease of specific surface area, and of thus decreased current density. The random orientations of $TiO_2$ nanowires can be preserved by the doctor blade process, resulted in the enhanced efficiency. The hybrid structured $TiO_2$ layer can possess the advantages of the high surface area of nanoparticles and the rapid electron transport rate and the light scattering effect of nanowires.

• 한국주조공학회지
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• 제19권5호
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• pp.419-426
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• 1999

Hardening behavior and metal-mold reaction of phosphate bonded investments for titanium and titanium alloys were investigated. Alumina and $Y_2O_3-stabilized$ zirconia, which are thermodynamically more stable than Titania, were used as major filler materials. $NH_4H_2PO_4$ was used as binder, and MgO was used as hardening acceleration material. A different composition ratio of binder and hardening acceleration material had effected on general hardening behavior and castings. And adding $YO_3-stabilized$ zirconia to alumina, metal-mold reaction characteristics for castings was evaluated. Considering working conditions and effects on castings, the best composition ratio conditions were both 10:10 and 12:8($NH_4H_2PO_4vs.\;MgO$). On the other hand, increasing the contents of $Y_2O_3-stabilized$ zirconia for filler material, metal-mold reaction layer of titanium castings was greatly decreased.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.234-235
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• 2007

Transparent nanosized $TiO_2$ sol has been made by sol-gel method, using Titanium(IV) isopropoxide precursor. To promote hydrolysis for titania is needed excess water, Oil bath and temperature about $80^{\circ}C$. $TiO_2$ sol is peptized ranging from pH 1 to 1.5 using hydrochloric acid for the stability of sol during a condensation reaction. The average particle size of $TiO_2$ sol was approximately 20nm. $TiO_2$-sillane sol was synthesized by surface treatment using MTMS to the $TiO_2$ sol. TEM analysis has been used to check the degree of dispersion and FT-IR analysis has been used to see if the sillane has been chemically bonded on the surface of $TiO_2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.306-306
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• 2007

The surface was transformed to porous titanium oxide by the anodization of pure titanium. Titanium was anodized in non-aqueous and aqueous electrolytes at different potentials between 5 V and 150 V. Various electrolytes were compose of ethylene glycerol, $H_2SO_4,\;NH_4F\;and\;H_2O$. We obtained titania nanotube arrays on the micro pore of titanium. Micro pores and nano tubes were obtained by anodization at high potentials and low potentials, respectively. Morphologies of nanotubes and micro pore were characterized by FE-SEM. The unique surface structure is very attractive to electrical and medical applications such as gas sensor, biosensor, dental implant and stent.

• 한국재료학회지
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• 제15권7호
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• pp.444-447
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• 2005

In this study, $Hydroxyapatite+TiO_2(HAp+TiO_2)$ composite sol coatings on Cp-Ti substrates were deposited by using a sol-gel derived precursor. Prior to hydroxyapatite coating, the samples were micropolished and divided into three sets. The first set was coated with hydroxyapatite (HAp) directly on Cp-Ti. The second set was first coated with intermediate titania layer and then coated with HAp. The third set samples were coated with $HAp+TiO_2$ (50:50) composite sol. Each samples were predried at $200^{\circ}C$, and heat treated 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 NaOH treated samples showed the presence of rutile crystal. The SEM studies revealed surface morphologies of each samples. $HAp+TiO_2$ composite sol coating layer was found to be smooth. The bonding strength of each samples were calculated using pull out tests. The bonding strength of the $HAp+TiO_2$ composite sol coating on substrate was 29.35MPa.

• 한국표면공학회지
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• 제34권4호
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• pp.321-326
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• 2001

The TiCrN Coatings haying three kinds of Compositions of $Ti_{36}$ $Cr_{26}$ $N_{38}$ , $Ti_{31}$ $Cr_{35}$ $N_{34}$ / and $Ti_{14}$ $Cr_{52}$ $N_{34}$ were deposited on STD 61 steel substrate by arc ion plating and were oxidized between 700 and 100$0^{\circ}C$ to identify the oxide scales formed on the coatings. The oxide scales were then analyzed using EPMA, XRD and GAXRD. During oxidation, the coatings consisting of TiN and CrN phases were reduced to TiO2 and $Cr_2$$O_3$, respectively. Titania tended to form at the outer oxide layer, whereas chromia tended to form at the inner oxide layer, owing to the different oxygen affinity. The substrate elements as well as coating elements diffused outwardly toward the oxide layer due to the concentration gradient. The growth of oxide from the TiCrN coatings was schematically expressed on the basis of thickness measurement of the reacted and unreacted coatings. The Cr element showed its stronger role to keep the TiCrN coatings from oxidation, when compared with Ni.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.173-179
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• 2018

Electrochemical characterization was conducted on poly(vinyl alcohol) (PVA)-ceramic composite (PVA-CC) separators for supercapacitor applications. The PVA-CC separators were fabricated by mixing various ceramic particles including aluminum oxide ($Al_2O_3$), silicon dioxide ($SiO_2$), and titanium dioxide ($TiO_2$) into a PVA aqueous solution. These ceramic particles help to create amorphous regions in the crystalline structure of the polymer matrix to increase the ionic conductivity of PVA. Supercapacitors were assembled using PVA-CC separators with symmetric activated carbon electrodes and electrochemical characterization showed enhanced specific capacitance, rate capability, cycle life, and ionic conductivity. Supercapacitors using the $PVA-TiO_2$ composite separator showed particularly good electrochemical performance with a 14.4% specific capacitance increase over supercapacitors using the bare PVA separator after 1000 cycles. With regards to safety, PVA becomes plasticized when immersed in 6 M KOH aqueous solution, thus there was no appreciable loss in tear resistance when the ceramic particles were added to PVA. Thus, the enhanced electrochemical properties can be attained without reduction in safety making the addition of ceramic nanoparticles to PVA separators a cost-effective strategy for increasing the ionic conductivity of separator materials for supercapacitor applications.