• Title/Summary/Keyword: $TiO_2$powder

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Photocatalytic Property of Nano-Structured TiO$_2$ Thermal Splayed Coating - Part I: TiO$_2$ Coating - (나노구조 TiO$_2$ 용사코팅의 미세조직 제어 공정기술 개발과 광촉매 특성평가 - Part I: TiO$_2$코팅 -)

  • 이창훈;최한신;이창희;김형준;신동우
    • Journal of Welding and Joining
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    • v.21 no.4
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    • pp.39-45
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    • 2003
  • Nano-TiO$_2$ photocatalytic coatings were deposited on the stainless steel 304(50$\times$70$\times$3mm) by the APS(Atmospheric Plasma Spraying). Photocatlytic reaction was tested in MB(methylene blue) aqueous solution. For applying nano-TiO$_2$ powders by thermal spray, the starting nano-TiO$_2$ powder with 100% anatase crystalline was agglomerated by spray drying. Plasma second gas(H$_2$) flow rate and spraying distance were used as principal process parameters which are known to control heat enthalpy(heat input). The relationship between process parameters and the characteristics of microstructure such as the anatase phase fraction and grain size of the TiO$_2$ coatings were investigated. The photo-decomposition efficiency of TiO$_2$ coatings was evaluated by the kinetics of MB aqueous solution decomposition. It was found that the TiO$_2$ coating with a lower heat input condition had a higher anatase fraction, smaller anatase grain size and a better photo-decomposition efficiency.

Synthesis and Photo Catalytic Activity of 10 wt%, 20 wt%Li-TiO2 Composite Powders (10 wt%, 20 wt%Li-TiO2 복합분말의 합성과 광촉매 활성평가)

  • Kim, Hyeong-Chul;Han, Jae-Kil
    • Journal of Powder Materials
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    • v.23 no.1
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    • pp.33-37
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    • 2016
  • 10 wt.% and 20 wt.%$Li-TiO_2$ composite powders are synthesized by a sol-gel method using titanium isopropoxide and $Li_2CO_3$ as precursors. The as-received amorphous 10 wt.%$Li-TiO_2$ composite powders crystallize into the anatase-type crystal structure upon calcination at $450^{\circ}C$, which then changes to the rutile phase at $750^{\circ}C$. The asreceived 20 wt%$Li-TiO_2$ composite powders, on the other hand, crystallize into the anatase-type structure. As the calcination temperature increases, the anatase $TiO_2$ phase gets transformed to the $LiTiO_2$ phase. The peaks for the samples obtained after calcination at $900^{\circ}C$ mainly exhibit the $LiTiO_2$ and $Li_2TiO_3$ phases. For a comparison of the photocatalytic activity, 10 wt.% and 20 wt.% $Li-TiO_2$ composite powders calcined at $450^{\circ}C$, $600^{\circ}C$, and $750^{\circ}C$ are used. The 20 wt.%$Li-TiO_2$ composite powders calcined at $600^{\circ}C$ show excellent efficiency for the removal of methylorange.

Photocatalytic Properties of TiO2 Nanopowder Synthesized by Chemical Vapor Condensation Process (화학기상응축 공정으로 제조한 TiO2 나노분말의 광촉매 특성)

  • 임성순;남희영;윤성희;이창우;유지훈;이재성
    • Journal of Powder Materials
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    • v.10 no.2
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    • pp.123-128
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    • 2003
  • $TiO_2$ nanopowder was synthesized by chemical vapor condensation (CVC) process and its photocatalytic property depending on microstructure was considered in terns of decomposition rate of organic compound. In order to control microstructure of $TiO_2$ nanopowder such as particle size and degree of agglomeration, precursor flow rate representing number concentration was changed as a process variable. In TEM observation, spherical $TiO_2$ nanoparticles with average size of 20 nm showed gradual increases in particle size and degree of agglomeration with increase of precursor flow rate. Also decomposition rate of organic compound increased with decreasing precursor flow rate. Thus, it was concluded that photocatalytic property was enhanced by targe surface area of disperse $TiO_2$ nanoparticles synthesized at lower precursor flow rate condition in CVC process.

Fabrication of Composite Powders by Mechanical Alloying of Magnetite-M (M = Ti, Al) Systems (마그네타이트와 금속(Ti, Al)의 기계적 합금화에 의한 복합분말의 합성)

  • 홍대석;이성희;이충효;김지순;권영순
    • Journal of Powder Materials
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    • v.11 no.3
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    • pp.247-252
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    • 2004
  • Recently, it has been found that mechanical alloying (MA) facilitates the nanocomposites formation of metal-metal oxide systems through solid-state reduction during ball milling. In this work, we studied the MA effect of Fe$_{3}$O$_{4}$-M (M = Al, Ti) systems, where pure metals are used as reducing agents. It is found that composite powders in which $Al_{2}$O$_{3}$ and TiO$_{2}$ are dispersed in $\alpha$-Fe matrix with nano-sized grains are obtained by mechanical alloying of Fe$_{3}$O$_{4}$ with Al and Ti for 25 and 75 hours, respectively. It is suggested that the large negative heat associated with the chemical reduction of magnetite by aluminum is responsible for the shorter MA time for composite powder formation in Fe$_{3}$O$_{4}$-Al system. X-ray diffraction results show that the reduction of magnetite by Al and Ti if a relatively simple reaction, involving one intermediate phase of FeAl$_{2}$O$_{4}$ or Fe$_{3}$Ti$_{3}$O$_{10}$. The average grain size of $\alpha$-Fe in Fe-TiO$_{2}$ composite powders is in the range of 30 nm. From magnetic measurement, we can also obtain indirect information about the details of the solid-state reduction process during MA.

The Synthesis of $BaTiO_3$ using continuous process in a bubble column reactor (기포탑반응기에서 연속공정을 이용한 $BaTiO_3$ 분말의 제조)

  • 현성호;김정환;허윤행
    • Journal of environmental and Sanitary engineering
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    • v.11 no.1
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    • pp.63-70
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    • 1996
  • The synthesis of high purity and ultra-fine $BaTiO_3$ by precipitation with gaseous $NH_3$ as precipitator was investigated to find an alternative process to solve various problems of recent wet methods. A synthesis process for $BaTiO_3$ powder using $NH_3$ gas as a precipitator in a bubble column reactor was experimentally successful in developing the production process of piezoelectric ceramic $BaTiO_3$ powder. And a 2.33m1/sec is approprite for the feed flow rate, $BaTiO_3$ powder produced under above the condition is spherical type, its particle size was about $0.2{\mu}m$.

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Preparation and Optoelectric Characteristics of Low Power Consumption Type AC Powder EL Devices with Dielectrics and Rear Contact (유전재료와 후면전극에 따른 저전력 소비형 AC Powder EL 소자 제조 및 광전기적 특성)

  • Lee, Kang-Ryeol;Park, Sung
    • Journal of the Korean Ceramic Society
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    • v.39 no.2
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    • pp.120-125
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    • 2002
  • AC powder EL devices were fabricated by screen printing method with the dielectric materials in insulating layer and the electrical resistivity of rear electrode. Brightness and current density were measured at voltage range of 50∼300 $V_{rms}$ to estimate optoelectrical properties of AC powder EL devices, respectively. Frequency generator was used as system producing frequency and voltage of a sine wave. Brightness and current density were measured by luminometer and multimeter. Also, dielectric constant for dielectric layer was measured by impedance analyser after preparing thick film. Dielectric constant was improved with amount of $TiO_2$ to $BaTiO_3$ powder. By applying such a process to dielectric layer of low cost AC powder EL device, brightness was improved to 50 cd/$m^2$ at similar current density. Dielectric constant $BaTiO_3$ powder by solution combustion process is better than commercial $BaTiO_3$ powder. By applying to that of low power consumption AC powder EL device, brightness was improved to 85 cd/$m^2$. Brightness of AC powder EL device was relatively decreased by control of electrical resistivity of rear electrode, current density was also decreased.

Characterization of NOx Reduction on Filter Bag Support System at Low Temperature using Powder Type MnOx and V2O2/TiO2 Catalysts (분말형 MnOx와 V2O2/TiO2 촉매를 이용한 저온영역의 백필터 공정에서 질소산화물 제거 특성)

  • Kim, Byung-Hwan;Kim, Jeong-Heon;Kang, Pil-Sun;Yoo, Seung-Kwan
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.1
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    • pp.1-9
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    • 2010
  • In this study, the selective catalytic reduction of $NO_x$ with ammonia was carried out in a filter bag support reactor. The experiments were performed by powder type $MnO_x$ and $V_2O_5$/$TiO_2$ catalyst at low temperature between 130 and $250^{\circ}C$. Also, the effect of $SO_2$ and $H_2O$ on the NO conversion was investigated under our test conditions. The powder type catalysts were analyzed by X-ray photoelectron spectrum (XPS), X-ray diffraction(XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was observed that NO removal efficiency of the powder type $V_2O_5$/$TiO_2$ catalyst was 85% at low temperature($200^{\circ}C$) under presence of oxygen and that of $MnO_x$ was 50% at the same condition. The powder type $V_2O_5$/$TiO_2$ catalyst, in conclusion, was found to be available for SCR reaction in a filter bag support system.

Characterization of TiO2 Synthesized in Acidic Conditions at Low Temperature by Sol-gel Method

  • Nguyen, Thanh Binh;Hwang, Moon-Jin;Lee, Seon-Sam;Choe, Dong-Eon;Ryu, Kwang-Sun
    • Journal of Powder Materials
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    • v.17 no.5
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    • pp.409-414
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    • 2010
  • Titanium dioxide ($TiO_2$), which is one of the most basic materials in our daily life, plays a key role for environment purification. We synthesized $TiO_2$ nanoparticles by the hydrolysis reactions of titanium tetraisopropoxide using $HNO_3$ as a peptizing agent or $CH_3COOH$ as a chelating agent in the sol-gel method. The powder consisted of a rod shape or a spherical shape according to the concentration and kind of acid. The physical properties of $TiO_2$ nanoparticles were investigated with X-ray diffraction, SEM, BET analysis, and UV-Vis spectrophotometer.

A Study on the Surface-Modification of Barium Sulfate/TiO$_2$/Dimethicone Composite Powder and its Application in Color Cosmetics (바륨설페이트/티타늄디옥사이드/디메치콘의 복합화 및 메이크업에서의 응용)

  • Kyung-Ho, Choi;Seung-Yong, Ko;Hak-Hee, Kang;Ok-Sub, Lee
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.30 no.2
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    • pp.197-200
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    • 2004
  • Sensor and optical properties have become critical features in powder foundation. The flaky barium sulfate powder shows good smooth texture, adhesion and natural looking characteristics. However, it has limitations abilities in UV shielding, hiding and blooming effect. Thus we adopt TiO$_2$ that has excellent hiding power and blooming effect as well as UV shielding ability, but TiO$_2$ has still intrinsic problems in dispersion and texture. To overcome this disadvantages, the barium sulfate/TiO$_2$/dimethicone composite powder was prepared. The flaky barium sulfate powder was coated with TiO$_2$ in nanoscale and followed by coated with dimethicone. When this surface-modified powder was applied for make-up cosmetics, especially in powder foundation, the powder gave powder foundation more good characteristics than the original flaky barium sulfate, Ti02 powder, dimethicone in abovementioned optical and sensory properties. To characterize the distinctive features of this surface-modified powder, we measured its characteristics with UV in vitro tester, hiding powder test method, goniophotometer, consumer panel test and so on.

Effect of Hydrothermal Conditions on the Phase Evolution of Lead Titanate (수열 합성 공정 조건이 티탄산 납의 상 형성에 미치는 영향)

  • Kim, Kyoung-A;Kim, Jeong-Seog;Cheon, Chae-Il
    • Journal of the Korean Ceramic Society
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    • v.48 no.1
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    • pp.99-105
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    • 2011
  • Lead titanate ($PbTiO_3$) powder was prepared from lead nitrate ($Pb(NO_3)_2$) and titania ($TiO_2$) by hydrothermal route. Phase formation process was investigated by observing the phases formed in various experimental conditions like different KOH concentration, reaction temperature and time. $PbTiO_3$ powder was fabricated when the KOH concentration was 0.8M or higher. An intermediate compound, $PbTi_{0.8}O_{2.6}$, was formed at first by a reaction between PbO and $TiO_2$ and changed into $PbTiO_3$ powder with a perovskite crystal structure. A $PbTiO_3$ phase was formed in a shorter time when a KOH concentration was increased from 0.8M to 8M because a driving force for a $PbTiO_3$ formation was increased due to an increase in a degree of supersaturation. And $TiO_2$ (rutile) and $3PbO{\cdot}H_2O$ were observed at room temperature in a 0.8M KOH solution and $TiO_2$(rutile) and PbO (litharge) in a 8M KOH. A $PbTiO_3$phase was also formed in a shorter time at a higher reaction temperature as a reaction temperature influenced the rates for a dissolution and a precipitation.