• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.112-113
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• 2003

• 한국분말재료학회지
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• 제18권6호
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• pp.532-537
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• 2011

Thermally stable $TiO_2$/Pt/$SiO_2$ core-shell nanocatalyst has been synthesized by chemical processes. Citrated capped Pt nanoparticles were deposited on amine functionalized silica produced by Stober process. Ultrathin layer of titania was coated on Pt/$SiO_2$ for preventing sintering of the metal nanoparticles at high temperatures. Thermal stability of the metal-oxide hybrid catalyst was demonstrated heating the sample up to $600^{\circ}C$ in air and by investigating the morphology and integrity of the structure by transmission electron spectroscopy. The surface analysis of the constituent elements was performed by X-ray photoemission spectroscopy. The catalytic activity of the hybrid catalysts was investigated by CO oxidation reaction with oxygen as a model reaction.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.440-441
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• 2006

Several titanate powders ($Al_2TiO_5,\;SrTiO_3$, etc.) were synthesized by an ethylene glycol solution route. Titanium isopropoxide and nitrate salts were dissolved in stoichiometric proportions in liquid-type ethylene glycol without any precipitation. The parent precursor sols were dried to porous gels, and then the gels were calcined and crystallized. All synthesized titanate powders had stable crystallization behavior at low temperature and high specific surface area after a simple ball-milling process. A three-component PZT $(Pb(Zr_{0.52}{\cdot}Ti_{0.48})O_3)$ powder was also synthesized successfully by the ethylene glycol method. In this study, the characteristics of the multi-component titanate powders by the ethylene glycol method are examined.

• 한국분말재료학회지
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• 제9권1호
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• pp.25-31
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• 2002

The efects of mechanical aloying conditions and the type of reducing agent on the solid state reductionof haematite $Fe_2O_3$ have been investigated at room temperature. Aluminium titanium zinc and copper were used as reducing agent. Nanocomposites of metal-oxide in which oxide particles with nano size were dispersed in Fe matrix were obtained by mechanical alloying of $Fe_2O_3$ with aluminium and titanium respectively However the reduction of $Fe_2O_3$ by coppe was not occurred Composite materials of iron with $Al_2O_3$ and $TiO_2$ were obtained from the system of $Fe_2O_3-Al$ and $Fe_2O_3-Ti$ after ball milling for 20 hrs and 30 hrs respectively. And the system of $Fe_2O_3-Zn$ resulted in the formationof FeO with ZnO after ball milling of 120 hrs. The final grain sizes of iron estimated by X-ray diffraction line-width measurement were in the ranges of 24~33 nm.

• 한국세라믹학회지
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• 제39권4호
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• pp.336-340
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• 2002

Pure and nano-sized $TiO_2$ and $CaTiO_3$ powders were fabricated by a polymeric steric entrapment route and planetary milling process. An ethylene glycol was used as a polymeric carrier for the preparation of organic-inorganic precursors. Titanium isopropoxide and calcium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. At the optimum amount of the polymer, the metal cations were dispersed in solution and a homogeneous polymeric network was formed. The dried precursor ceramic gels were turned to porous powders through calcination process. The porous powders were crystallized at low temperatures and the crystalline powders were planetary milled to nano size.

• 한국분말재료학회지
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• 제31권3호
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• pp.255-262
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• 2024

Nano-oxide dispersion-strengthened (ODS) superalloys have attracted attention because of their outstanding mechanical reinforcement mechanism. Dispersed oxides increase the material's strength by preventing grain growth and recrystallization, as well as increasing creep resistance. In this research, atomic layer deposition (ALD) was applied to synthesize an ODS alloy. It is useful to coat conformal thin films even on complex matrix shapes, such as nanorods or powders. We coated an Nb-Si-based superalloy with TiO₂ thin film by using rotary-reactor type thermal ALD. TiO₂ was grown by controlling the deposition recipe, reactor temperature, N₂ flow rate, and rotor speed. We could confirm the formation of uniform TiO₂ film on the surface of the superalloy. This process was successfully applied to the synthesis of an ODS alloy, which could be a new field of ALD applications.

• 한국세라믹학회지
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• 제39권1호
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• pp.38-44
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• 2002

여러 종류의 전해질이 존재할 때, 수계 및 비수계 분산매체에서 저온균일침전법으로 제조된 침상형태의 일차입자를 갖는 나노 크기의 루틸상 TiO$_2$분말에 대한 분산 안정성을 조사하였다. 제타전위 측정은 수계 및 비수계 분산매체에 전해질 첨가가 TiO$_2$입자 표면의 전위 역전을 유발하는 것을 보여주었다. 비수계 분산매체에 분산되어 있는 TiO$_2$입자 사이에 작용하는 정전기적 반발력은 수계 분산매체에서보다 크게 관찰되었고, 이것은 점도, 유전 상수와 같은 유기 용매의 물리적 특성과 밀접한 연관이 있음을 알 수 있었다. pH, 전해질의 농도와 이온의 원자가는 TiO$_2$입자의 표면전위를 크게 변화시켰고, TiO$_2$입자의 분산 거동을 사실상 주도하였다.

• 청정기술
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• 제29권2호
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• pp.118-125
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• 2023

부지가 폴리염화비페닐(polychlorinated biphenyls, PCBs)로 오염되면, 심각한 환경 및 건강 위해를 피할 수 없게 된다. 따라서 혁신적이지만 경제성을 지니는 제자리 복원 기술이 오염 부지에 즉시 적용되어야 한다. TCE, PCE 및 DDT와 같은 염소계 유기화합물의 탈염소화를 위하여 최근에는 나노 규모의 영가-철(zero-valent iron, ZVI)이 성공적으로 적용되었고, 지구 지각에서도 풍부하게 존재하는 철은 환경적으로 안전한 것으로 통상적으로 간주된다. 입상 ZVI에 비해 나노 규모 ZVI의 반응성은 훨씬 높지만, 높은 표면에너지와 자기적 물성 때문에 나노 규모 ZVI 입자들은 서로 응결된다. 서로 응결되어 큰 입자로 전환되는 것을 방지하기 위해 먼저 생성된 나노 ZVI 입자들을 가능한 고정화하기 위한 방안으로 TiO₂ 분말에 나노 ZVI를 담지하였다. FeSO₄와 TiO₂ 분말의 수용액상 슬러리에 NaBH₄를 천천히 첨가하여10wt% ZVI/TiO₂를 제조하였다. 입자 크기의 불균일성에도 불구하고, 나노 ZVI 입자들이 TiO₂ 외부 표면에 성공적으로 분산되었다. 제조된 ZVI/TiO₂는 PCBs의 표준 물질 일종인 Aroclor 1242로 인위적으로 오염시킨 토양의 PCBs 분해 실험에 적용되었고, Aroclor 1242 분해 성능을 관찰하였다. 제조된 ZVI/TiO₂는 Aroclor 1242 분해에 꽤 높은 반응성을 보였지만, 분자량이 큰 탄화수소로 판단되는 화합물이 부산물로 생성되어 토양에 잔류하는 것은 피할 수 없었다.

• 한국분말재료학회지
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• 제28권5호
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• pp.423-428
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• 2021

Here, we report the development of a new and low-cost core-shell structure for lithium-ion battery anodes using silicon waste sludge and the Ti-ion complex. X-ray diffraction (XRD) confirmed the raw waste silicon sludge powder to be pure silicon without other metal impurities and the particle size distribution is measured to be from 200 nm to 3 ㎛ by dynamic light scattering (DLS). As a result of pulverization by a planetary mill, the size of the single crystal according to the Scherrer formula is calculated to be 12.1 nm, but the average particle size of the agglomerate is measured to be 123.6 nm. A Si/TiO₂ core-shell structure is formed using simple Ti complex ions, and the ratio of TiO₂ peaks increased with an increase in the amount of Ti ions. Transmission electron microscopy (TEM) observations revealed that TiO₂ coating on Si nanoparticles results in a Si-TiO₂ core-shell structure. This result is expected to improve the stability and cycle of lithium-ion batteries as anodes.

• 한국가스학회지
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• 제13권2호
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• pp.23-29
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• 2009

Pt, Pd, In 등의 촉매금속을 사용하여 아세토나이트릴 유독가스에 대한 감도를 향상시키는 SnO2 가스센스에 대하여 연구하였다. Metal-SnO2 후막은 백금전극이 내장된 알루미나 지지체의 스크린법으로 제작되었다. 본 센서의 특성은 검출가스의 농도의 함수로 반응기내 각센서의 전기적 저항을 측정하여 조사하였으며, 10-50ppm 범위의 유독가스 농도에 대하여 검지 측정하였다. 그 결과 촉매금속의 종류에 따라 센서에서 반응하는 감도가 각각 다르게 선택성을 갖고 있는 것으로 나타났다.