• Title/Summary/Keyword: TiO2 분말

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Preparation of hydroxyapatite/$TiO_2$ biocomposite powders by wet chemical method (습식화학법에 의한 수산화아파타이트/$TiO_2$ 생체용 복합분말의 제조)

  • 정항철;이종국
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.14 no.3
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    • pp.83-89
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    • 2004
  • In this work, HA/$TiO_2$ biocomposite to get high mechanical properties with biocompatibility were prepared. HA/$TiO_2$ biocomposite powders were prepared by mixing $TiO_2$ and HA powders which were synthesized through sol-gel, precipitation and hydrothermal methods. The mixing ratio was fixed at 1:1 ratio (HA/$TiO_2$, wt%). HA/$TiO_2$ biocomposite powders showed different microstructures depending on their particle size and shape. The smaller particles were coated on the surface of larger particles, whereas they were well mixed and dispersed when both $TiO_2$ and HA were nanocrystallites. HA/$TiO_2$ biocomposite powders with homogeneous microstructure showed high sintered density and good mechanical properties.

Study on the Powder Synthesis of $BaTiO_3$ and its Dielectric Properties (초소형 캐패시터용 $BaTiO_3$분말합성 및 소결특성에 관한 연구)

  • 문흥수;박병규;이태근;김철긴;이석근
    • Korean Journal of Crystallography
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    • v.10 no.1
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    • pp.56-65
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    • 1999
  • 수열법을 이용하여 미세한 BaTiO3 분말을 합성하였다. Ti원으로 두 종류의 TiO2 gel을 사용하였으며 그 크기와 모양을 BaTiO3 합성에 주는 영향을 고찰하였다. 구형의 단분산 TiO2 gel을 사용하여 Ba(NO3)2 수용액에서 수열 합성한 BaTiO3 분말은 입자크기도 균일하였으며 응집이 일어나지 않아않았다. 비교적 낮은 pH에서 구형 TiO2 gel을 사용하여 합성한 BaTiO3 분말은 구형을 그대로 유지하였지만 높은 pH에서 합성한 BaTiO3 분말은 그 구형이 분해되었다. KOH양이 많아지고, 합성시간이 길어짐에 따라 합성된 BaTiO3 분말의 크기는 커졌으며 그 c/a 값도 증가하였다.

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A Study on the Properties of Alumina Ceramics as the Amount of $\textrm{TiO}_2$ Addition ($\textrm{TiO}_2$ 첨가량에 대한 알루미나 세라믹스의 특성에 관한 연구)

  • Ryu, Su-Chak
    • Korean Journal of Materials Research
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    • v.9 no.9
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    • pp.900-904
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    • 1999
  • The effects of Tio$_2$addition on the microstructural evolution and mechanical properties of alumina ceramics were studied. Bulk density decreased with an increase of the amount of TiO$_2$. Apparent porosity decreased with an increase of the amount of TiO$_2$ up to 7wt%. But beyond 9wt% of TiO$_2$powders, apparent porosity increased. In the compression test, the modulus increased with an increase of the amount of TiO$_2$addition. In the three point bending test, the stress at yield decreased with an increase of the amount of TiO$_2$ addition. The addition. The addition of TiO$_2$ promoted the grain growth of alumina ceramics.

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Synthesis of TiO2-xNx Using Thermal Plasma and Comparison of Photocatalytic Characteristics (열플라즈마에 의한 TiO2-xNx의 합성 및 광촉매 특성 비교)

  • Kim, Min-Hee;Park, Dong-Wha
    • Applied Chemistry for Engineering
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    • v.19 no.3
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    • pp.270-276
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    • 2008
  • $N_2$ doped $TiO_2$ nano-sized powder was prepared using a DC arc plasma jet and investigated with XRD, BET, SEM, TEM, and photo-catalytic decomposition. Recently the research interest about the nano-sized $TiO_2$ powder has been increased to improve its photo-catalytic activity for the removal of environmental pollutants. Nitrogen gas, reacting gas, and titanium tetrachloride ($TiCl_4$) were used as the raw materials and injected into the plasma reactor to synthesize the $N_2$ doped $TiO_2$ power. The particle size and XRD peaks of the synthesized powder were analyzed as a function of the flow rate of the nitrogen gas. Also, the characteristics of the photo-catalytic decomposition using the prepared powder were studied. For comparing the photo-catalytic decomposition performance of $TiO_2$ powder with that of $TiO_2$ coating, $TiO_2$ thin films were prepared by the spin coating and the pulsed laser deposition. For the results of the acetaldehyde decomposition, the photo-catalytic activity of $TiO_{2-x}N_x$ powder was higher than that of the pure $TiO_2$ powder in the visible light region. For the methylene blue decomposition, the decomposition efficiency of $TiO_2$ powder was also higher than that of $TiO_2$ film.

Preparation of β-TCP/TiO2 Composite by Hot-Pressing (가압소결에 의한 β-TCP/TiO2복합체의 제조)

  • 정항철;이종국
    • Journal of the Korean Ceramic Society
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    • v.41 no.3
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    • pp.202-209
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    • 2004
  • Hydroxyapatite(HA)/TiO$_2$ composite powders were prepared by mixing of spherical TiO$_2$ (10-15 nm, 500 nm) and needle-shaped HA (50-70 nm, 120-250 nm) powders which had been synthesized through precipitation, sol-gel and hydrothermal methods. From the three types of starting composite powders (HA/TiO$_2$ wt% of 75/25, 50/50, and 25/75), dense $\beta$-TCP/TiO$_2$ composites were prepared by hot-pressing at 800-100$0^{\circ}C$ for 30 min under the pressure of 30 ㎫ in Af atmosphere. The $\beta$-TCP/TiO$_2$ composites showed different microstructures and sintering densities depending on their powder morphology, composition and sintering temperature. With increasing the sintering temperature and the content of TiO$_2$, sintered density was increased and microstructure became more homogeneous.

Modification of Graphite Surface By the Hydrothermal Coating of $TiO_2$ ($TiO_2$ 수열코팅에 의한 흑연의 표면 개질)

  • 최승도;박병규
    • Korean Journal of Crystallography
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    • v.8 no.2
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    • pp.154-159
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    • 1997
  • Hydorthemal coating technique has been sucessfully applied to improve oxidation resistance of graphite by forming rutile-TiO2 layer. Hydrothermal treatment of graphite in 0.2M TiCl4 aquous solution at 35℃ resulted in improved water wettability due to the formation of surface-modifying TiO2. The amount of TiO2 increased with temperature. In the presence of surface TiO2 layer, weight loss was reduced by 30%, while the initiation temperature of oxidation was lowered by 30℃.

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FeO, $TiH_2$, Carbon 원료분말을 이용한 Fe-TiC 나노 복합분말 제조 및 소결

  • An, Gi-Bong;Kim, Ji-Sun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.10a
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    • pp.26-26
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    • 2011
  • Fe계 TiC 합금은 미량의 합금원소를 첨가시켜 경화능, 내식성, 내마모성 성질을 개선한 특수 공구용 재료로서 현재 절삭, 내마모성, 광산, 금형재료 등의 분야에 널리 사용되고 있다. 금속과 세라믹의 복합재료인 초경합금은 비열처리용 공구강으로 WC, TiC 등의 4, 5, 6족 금속탄화물에 Co, Ni, Fe등의 철족이 결합금속으로 소결한 복합재료로 WC-Co계 초경합금이 주종을 이루고 있으나, 전략 소재로서 고가인 Co 원료를 대체하기 위한 재료로서 초경재료의 고경도와 공구강의 경제성 및 가공성의 장점을 이용한 Fe-TiC계 초경합금의 연구가 다양하게 진행되고 있다. 본 연구에서는 Fe기지에 서브마이크론 크기의 미세한 TiC 입자가 균일하게 분산된 Fe-TiC 복합분말을 경제적으로 제조하기 위해 순수한 Fe, Ti 원료분말에 비해 단가가 낮고 미세 분쇄가 용이한 FeO, $TiH_2$ 분말을 고에너지 밀링 후 반응 열처리 시키는 유사 기계화학적 공정을 시도하였다. 조성비 Fe-30wt%TiC 복합분말을 제조하기위해 마이크론(micron) 크기의 FeO, $TiH_2$, C 분말을 사용하였고, 1단계로 FeO와 C을 고에너지 밀링으로 혼합 후 반응시켜 환원시키는 공정과 2단계로 이렇게 환원된 분말과 TiH2를 고에너지 밀링으로 다시 혼합, 분쇄한 후 반응열처리 하는 두 단계 공정을 사용하였다. FeO의 환원 단계에서는 $700{\sim}1,000^{\circ}C$ 온도 범위에서 1시간 유지하였고, 고에너지 밀링 시 밀링시간, 회전속도를 변수로 두고 실험하였다. 환원된 분말은 수평관상로를 이용해 아르곤분위기에서 $1,000{\sim}1300^{\circ}C$까지 1시간 유지하여 반응열처리시켜 Fe-TiC 복합분말을 제조하였다. 준비된 복합분말을 XRD와 FE-SEM, EDS, 입도분석기 (LPSA) 등을 이용해 분말의 형태와 특성, 상, 조성, 입도, 분산도 등을 조사하였다. 제조된 Fe-TiC 나노복합분말을 방전플라즈마소결(SPS) 과 상압소결 실험을 진행하였다. Fe-TiC 복합분말 제조공정의 첫 번째 단계인 FeO의 환원반응은 $800^{\circ}C$이상의 온도에서 Fe로 환원이 진행됨을 확인하였다. 두 번째 단계인 반응열처리공정에서는 $1,000^{\circ}C$ 이상에서 TiC가 형성됨을 XRD 상분석을 통해 확인할 수 있었고, $1,100^{\circ}C$ 이상의 온도에서 반응열처리를 했을 때 XRD 분석결과와 산소 조성 분석 결과로부터 반응의 완결성과 순도에서 최적 온도 조건임을 확인하였다. 온도를 $1,300^{\circ}C$로 증가시킬 경우 반응의 완결성에 큰 변화가 없는 반면 분말입자간의 목형성이 일어나 가소결 되는 것을 FE-SEM을 통해 관찰하였다. 또한 최적조건으로 제조된 Fe-TiC 복합분말의 입도분석과 FE-SEM/EDS 관찰/분석을 시행한 결과 평균 입도 0.6 ${\mu}m$의 미세한 Fe-TiC 복합분말 내에 Fe분말 주변과 내부에 나노크기의 TiC입자가 균일하게 분산되어 존재하는 것을 확인하였다.

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Synthesis and characterization of $BaTiO_3$ fine particles by hydrothermal process (수열합성법에 의한 미립의 $BaTiO_3$ 분말합성 및 특성)

  • 배동식;주기태;한경섭;최상흘
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.4
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    • pp.563-566
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    • 1998
  • $BaTiO_3$ fine particles were prepared by hydrothermal process from titanium tetra-isoproproxide ($Ti(OiPr)_4$) and barium hexa-hydroxide ($Ba(OH)_2{cdot}8H_2O$) as raw materials. The fine particles were obtained at the temperature range of 160 to $185^{\circ}C$. The properties of $BaTiO_3$ particles were studied as a function of various parameters such as reaction temperature, reaction time and Ba/Ti ratio, etc. The average particle size of $BaTiO_3$ increased with increasing reaction temperature and time. After hydrothermal treatment at $170^{\circ}C$ for 8 h, the average particle size of $BaTiO_3$ was about 30 nm and the particle size distribution was narrow.

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Formation Rate of Tetragonal BaTiO3 Powder by Hydrothermal Synthesis and its Dielectric Property (수열합성법에 의한 정방정 BaTiO3 분말의 생성속도 및 유전특성)

  • 이종현;최용각;원창환;김채성
    • Journal of the Korean Ceramic Society
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    • v.39 no.7
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    • pp.628-634
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    • 2002
  • Formation rate of tetragonal BaTiO$_3$powder by hydrothermal synthesis and its dielectric property were studied. Submicron tetragonal BaTiO$_3$ powders were prepared hydrothermally, using Ba(OH)$_2$.8$H_2O$, TiO$_2$(anatase) and KOH as starting chemicals. Characterization via X-ray diffractometry, field emission scanning electron microscopy confirmed that increasing calcination temperatures(from 1100 to 130$0^{\circ}C$) promotes the formation of tetragonal BaTiO$_3$. Tetragonal BaTiO$_3$ ceramics, obtained by calcining at 1200 for 3 h after hydrothermal synthesis at 200 for 168 h, exhibited submicron size of 0.5 ~ 0.7 ${\mu}{\textrm}{m}$ and high relative permittivity.

Hydrothermal Synthesis and Characterization of BaTiO3 Fine Powders (BaTiO3 미세 분말의 수열합성 및 특성분석)

  • Park, Jung-Hoon;Park, Sangdo
    • Korean Chemical Engineering Research
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    • v.45 no.5
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    • pp.448-454
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    • 2007
  • Hydrothermal synthesis was conducted with starting material as Barium hydroxide and hydrous titania ($TiO_2{\cdot}xH_2O$) to obtain barium titanate fine Powder. The conversion, crystal structure and properties of as-prepared powder were investigated according to reaction temperature, time and concentration. The effect of variables on conversion was in order of time < temperature < concentration and the maximum conversion reached to 99.5% in the case of hydrothermal synthesis at $180^{\circ}C$ for 2 h with 2.0 M reactant concentration. At low concentration such as 0.25 M, formation of unreacted $BaCO_3$ and $TiO_2$ was not inevitable at even high reaction temperature and these components converted into $BaTi_2O_5$ at high temperature and remained as impurity. As concentration of reactant increased, the size of as-synthesized $BaTiO_3$ powder deceased and Ba/Ti molar ratio approached into 1, showing Ba/Ti ratio of $1{\pm}0.005$ for reaction at $180^{\circ}C$ for 2 h with 2.0 M concentration.