• 대한기계학회논문집B
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• 제25권9호
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• pp.1175-1182
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• 2001

Chemical compositions of polydisperse SiO$_2$/TiO$_2$multicomponent aggregates were measured for different heights from the burner surface and different mobility diameters of aggregates. SiO$_2$/TiO$_2$multicomponent particles were generated in a hydrogen/oxygen coflow diffusion flame from two sets of precursors: TTIP(titanium tetraisopropoxide), TEOS(tetraethylorthosilicate). To maintain 1:1 mole ratio of TTIP:TEOS vapor, flow rate of carrier gas $N_2$was fixed at 0.6lpm for TTIP, at 0.1lpm for TEOS. In-situ sampling probe was used to supply particles into DMA(differential mobility analyzer) which was calibrated with using commercial DMA(TSI, model 3071A) and classifying monodisperse multicomponent particles. Classified monodisperse particles were collected with electrophoretic collector. The distributions of composition from particles to particle were determined using EDS(energy dispersive spectrometry) coupled with TEM(transmission electron microscope). The chemical(atomic) compositions of classified monodisperse particle were obtained for different heights; z=40mm, 60mm, 80mm. The results suggested that the chemical(atomic) composition of SiO$_2$decreased with the height from burner surface and the composition of SiO$_2$and TiO$_2$approached to the value of 1 to 1 fat downstream. It is also found that the composition of SiO$_2$decreases as the mobility diameter of aggregate increases.

• 한국분말재료학회지
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• 제12권6호
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• pp.447-452
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• 2005

The synthesis and consolidation of titanium silicide by electro-discharge-sintering has been investigated. As-received Ti powder was in flaky shape and the mean particle size was $45.0{\mu}m$, whereas the mean particle size of the pre-milled Si powder with angular shape was $8.0{\mu}m$. Single pulse of 2.5 to 5.0 kJ/0.34g-elemental Ti and pre-milled Si powder mixture with the composition of $Ti-37.5at.\%$ Si was applied using $300{\mu}F$ capacitor. The solid with $Ti_5Si_3$ phase has been successfully fabricated by the discharge with the input energy more than 2.5kJ in less than $129{\mu}sec.$ Hv values were found to be higher than $1000kgf/mm^2$. The formation of $Ti_5Si_3$ occurred through a fast solid state diffusion reaction.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3317-3322
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• 2011

This study examines the photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs) when nanometer-sized Zr (0.1, 0.5, and 1.0 mol %)-$TiO_2$ prepared using a solvothermal method is utilized as the working electrode material. The particle sizes observe in the transmission electron microscopy (TEM) images are < 30 nm in all samples. The absorption band is slightly broadened at the tail for the 0.1 mol % Zr-$TiO_2$, and the intensity of the photoluminescence (PL) curves of the Zr-incorporated $TiO_2$ is significantly smaller than that of the pure $TiO_2$. Compared to that using pure $TiO_2$, the energy conversion efficiency is enhanced considerably by the application of Zr-$TiO_2$ in the DSSCs to approximately 6.17% for 0.5 mol % Zr-$TiO_2$ with the N719 dye (10.0 ${\mu}m$ film thickness and 5.0 mm ${\times}$ 5.0 mm cell area) under 100 mW/$cm^2$ of simulated sunlight.

• 한국세라믹학회지
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• 제25권5호
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• pp.50-50
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• 1988

Ti(OC2H5)4 농도, 물량, 용매, alcohol을 변화시켜 가수분해 반응 특성을 검토하였으며 submicron 구형 단분산 분말을 합성하기 위하여 연구를 수행하였다. TEOT 농도와 물량이 증가하면 가수분해 반응속도는 빨라지며 생성입자 size는 작아졌다. TEOT 농도가 0.1~-0.2 M, 물량이 3배일때 양호한 구형 단분산 분말을 얻을 수 있었다. 용매 alcohol의 탄소가지수가 많거나 탄소가지수가 길어지면 가수분해 반응속도는 늦어짐을 알 수 있었다. 제조된 TiO2분말의 평균입경은 0.8㎛ 정도의 구형단분산 입자이며 가열시 결정상은 550℃ 이상에서 Rutile을 확인할 수 있었으며 입자 size도 0.6~0.7 u로 감소하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.374-378
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• 1999

Thin Films of BaYTiO system were Prepared by frequency (rf)/dc magnetron sputtering method. The preparation of target were accomplished by the mixed oxide method, and their composition consisted of the $Ba_{0.997}$ $Y_{0.003}$Ti $O_3$+0.5 $SiO_2$+x $M_{n}$O(x=0, 0.073, 0.1, 0.127, 0.154). The average particle size of (Ba,Y)Ti $O_2$ system ceramics with Mn $O_2$ additives increases as the amount of MnO additives increase and reaches the maximum grain growth when the amount of MnO is 0.127(mol%).).).).

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.609-614
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• 2008

A periodic mesoporous organosilica material was synthesized by microwave heating (PMO-M) using 1,2-bis(trimethoxysilyl)ethane as a precursor in a cationic surfactant solution, and textural properties were compared with those of the product produced by conventional convection heating (PMO-C). These synthesized materials were characterized using XRD, TEM/SEM, N2 adsorption isotherm, 29Si and 13C NMR, and TGA, which confirmed their good structural orders and clear arrangements of uniform 3D-channels. Synthesis time was reduced from 21 h in PMO-C to 2-4 h in PMO-M. PMO-M was made of spherical particles of 1.5-2.2 m m size, whereas PMO-C was made of decaoctahedron-shaped particles of ca. 8.0 m m size. Effect of synthesis temperature, time, and heating mode on the PMO particle morphology was examined. The particle size of PMO-M could be controlled by changing the heating rate by adjusting microwave power level. PMO-M demonstrated improved separation of selected organic compounds compared to PMO-C in a reversed phase HPLC experiment. Ti-grafted PMO-M also resulted in higher conversion in liquid phase cyclohexene epoxidation than by Ti-PMO-C.

• 대한치과기공학회지
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• 제31권4호
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• pp.15-23
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• 2009

The aim of this study was to evaluate the bond strength of using a Au bonding agent applied on cp-Ti and nonprecious metal-gold-ceramic system. Metallic frameworks(diameter: 5mm, height: 20mm)(N=56, n=7per group) cast in Ni-Cr alloy, Co-Cr alloy and cp-Ti were obtained using acrylic templates and airborne particle abraded with $110{\mu}m$ aluminum oxide. Au bonding agent was applied on wash opaque firing as intermediate layer. SEM and SEM/EDS line profile were performed on the cutting the cross-section of the metal substrate-porcelain with intermediate Au coating. Groups were tested using shear bond strength(SBS) testing at 0.5mm/min. The mean SBS values for the ceramic-Au layer-metal combination were significantly higher than those ceramic-metal combination. While ceramic-Au layer-cp-Ti combinations failed to increase bond strength instead of using a titanium bonding porcelain. The appication of using Au intermediate layer significantly improve the bond strength combination with metal-ceramic system.

• 산업기술연구
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• 제28권A호
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• pp.19-22
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• 2008

In recent years, much attention has been paid to "Photocatalytic oxidation" as an alternative technique, where the pollutants are degraded by UV-irradiation in the presence of a semiconductor suspension such as titanium dioxide. $TiO_2$ is the most often used photocatalyst due to its considerable photocatalytic activity, high stability, non-environmental impact and low cost. 1n this research, the photocatalytic degradation of humic acid, acetaldehyde and methylene blue in $UV/TiO_2$ systems has been stydied. The effect of calcination temperature for manufacturing of $TiO_2$ photocatalysts and type of photocatalysts on photodegradation has been investigated. Photocatalysts with various metal ions(Mn, Fe, Cu and Pt) loading are tested to evaluate the effects of metal ions impurities on photodegradation. The photodegradation efficiency with $Pt-TiO_2$ or $Fe-TiO_2$ or $Cu-TiO_2$ is higher than Degussa P-25 powder. However, the photodegradation efficiency with $Mn-TiO_2$ is lower than Degussa P-25 powder. The photocatalytic properties of the nanocrystals were strongly dependent upon the crystallinity, particle size, standard reduction potential of various transition metal and electronegativity of various transition metal. As a result photocatalysts with various metal ion loading evaluated the effect of photodegradation.

• Journal of Advanced Marine Engineering and Technology
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• 제33권7호
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• pp.1044-1051
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• 2009

During contact between surfaces, there is wear and the generation of wear. The particles contained in the lubricating oil carry detailed and important monitoring information about the condition of the machine. Therefore, this paper was undertaken for the Ferrography system of wear debris generated from a lubricated moving machine surface. The lubricating wear test was performed under different experimental conditions using the Falex wear test of the Pin and V-Block types by Ti(C,N) coated. It was shown from the test results that wear particle concentration(WPC), wear severity index(Is) and size distribution have come out all higher with increases in sliding friction time. With the Ferrogram thin leaf wear debris as well as ball and plate type wear particles were observed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.120-123
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• 2000

This paper reports a newly developed sol-gel process to synthesize dense YBCO thick films with BaTiO$_3$additives using electrophoretic deposition and metal alkoxide sol/particle suspension, which we successfully produce dense $YBCO+BaTiO_3$ ceramics at a rather low temperature, compared with the sintering temperature used in conventional methods. The thick films of HTS were prepared by electrophoretic deposition, using pre-sintered powder with barium titanate addition in the form of $BaTi(OR)_6$ solution in suspension for electrophoresis. The conditions for applied voltage and deposition times for electrophoretic deposition of HTS thick films were studied in detail.