• Corrosion Science and Technology
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• 제6권6호
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• pp.311-315
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• 2007

The anodic polarization behavior of equiatomic TiNi shape memory alloy with pure titanium as a reference material was investigated by means of open circuit potential measurement and potentiodynamic polarization technique. And the structure of passive films on TiNi intermetallic compounds was also conducted using AES and ESCA. While the dissolved Ni(II) ion did not affect the dissolution rate and passivation of TiNi alloy, the dissolved Ti(III) ion was oxidated to Ti(IV) ion on passivated TiNi surface at passivation potential. It has also been found that the Ti(IV) ion increases the steady state potential, and passivates TiNi alloy at a limited concentration of Ti(IV) ion. The analysis by AES showed that passive film of TiNi alloy was composed of titanium oxide and nickel oxide, and the content of titanium was three times higher than that of nickel in outer side of passive film. According to the ESCA analysis, the passive film was composed of $TiO_2$ and NiO. It seems reasonable to suppose that NiO could act as unstabilizer to the oxide film and could be dissolved preferentially. Therefore, nickel oxide contained in the passive film may promote the dissolution of the film, and it could be explained the reason of higher pitting susceptibility of TiNi alloy than pure Ti.

• Corrosion Science and Technology
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• 제9권4호
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• pp.171-174
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• 2010

MAO (micro-arc oxidation) is an eco-friendly convenient and effective technology to deposit high-quality oxide coatings on the surfaces of Ti, Al, Mg and their alloys. The roles of the electrolyte concentration and relative cathode electrode area sizes in the grown oxide film during titanium MAO were investigated. The higher the concentration of the electrolyte, the lower the $R_{total}A$ value. The oxide film produced by the lower concentration of the electrolyte is thinner and less uniform than the film by the higher concentration, which is thick and porous. The cathode area size must be bigger than the anode area size in order to minimize the voltage drop across the cathode. The ratio of the cathode area size to the anode area size must be bigger than 8. Otherwise, the cathode will be another source for voltage drop, which is detrimental to and slows down the oxide growth.

• 한국재료학회지
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• 제17권1호
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• pp.6-10
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• 2007

In the present study, we investigated the formation of self-organized nanostructure oxide layers on CP Ti and Ti-10Ta-10Nb alloy in an electrolyte of 1M phosphoric acid and 1.5 wt% Hydrofluoric acid. The morphology of oxide film on substrate was observed using scanning electron microscopy and transmission electron microscopy The surface roughness of titanium oxide film was analyzed by atomic force microscopy and the crystalline of specimen was investigated using X-ray diffractometer. The results of this study showed that well-aligned titanium oxide nanotubes are formed with diameter of approx. 100nm and length of approx. 500nm with CP Ti. However, it is clear that TiTaNb alloy highly irregular structure with various diameters. Transmission electron microscope investigations show that the specimens were confirmed as amorphous. Such titanium oxide nanotubes are expected a well-adhered bioacitive surface layer on titanium substrate for orthopedics and dental implants.

• 한국재료학회지
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• 제19권6호
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• pp.325-329
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• 2009

Titanium dioxide thin films were fabricated as hydrogen sensors and its sensing properties were tested. The titanium was deposited on a $SiO_2$/Si substrate by the DC magnetron sputtering method and was oxidized at an optimized temperature of $850^{\circ}C$ in air. The titanium film originally had smooth surface morphology, but the film agglomerated to nano-size grains when the temperature reached oxidation temperature where it formed titanium oxide with a rutile structure. The oxide thin film formed by grains of tens of nanometers size also showed many short cracks and voids between the grains. The response to 1% hydrogen gas was ${\sim}2{\times}10^6$ at the optimum sensing temperature of $200^{\circ}C$, and ${\sim}10^3$ at room temperature. This extremely high sensitivity of the thin film to hydrogen was due partly to the porous structure of the nano-sized sensing particles. Other sensor properties were also examined.

• 한국진공학회지
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• 제6권S1호
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• pp.1-15
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• 1997

Titanium oxide films were prepared by ion beam enhanced deposition where the films were synthesized by deposition titianium atoms and simultaneously bombarding with xenon ion beam at an energy of 40 keV in an $O_2$ environ,ent. Structure and composition of titanium oxide films were investigated by X-ray Doffractopm (XRD) Ritjerfprd Backscattering Spectroscopy (RBS) and X-ray Diffraction(XRD) Rutherford Backscattering Spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS) The results show that thestructure of the prepared films exhibit a rutile phase structure wit high(200) orientation and the O/Ti ratio of the titanium oxide films was about 2:1 XPS anlysis shows that $Ti^{2+},Ti^{3+}\;and\;Ti^{4+}$ chemical states exist on the titanium oxide films. the blood compatibility of the titanium oxide films was studied by measurements of blood clotting time and platelet adhesion. The results show that the anticoagulation property of titanium oxide films improved significantly and better than that of LTI-carbon which was widely used to fabricate artificial heart valve.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.684-687
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• 2011

In this study, we investigate the photovoltaic performance of transparent conductive indium tin oxide (ITO), titanium-doped indium oxide (ITiO), and fluorine-doped tin oxide (FTO) films. ITO and ITiO films are prepared by radio frequency magnetron sputtering on soda-lime glass substrate at $300^{\circ}C$, and the FTO film used is a commercial product. We measure the X-ray diffraction patterns, AFM micrographs, transmittance, sheet resistances after heat treatment, and transparent conductive characteristics of each film. The value of electrical resistivity and optical transmittance of the ITiO films was $4.15{\times}10^{-4}\;{\Omega}-cm$. The near-infrared ray transmittance of ITiO is the highest for wavelengths over 1,000 nm, which can increase dye sensitization compared to ITO and FTO. The photoconversion efficiency (${\eta}$) of the dye-sensitized solar cell (DSC) sample using ITiO was 5.64%, whereas it was 2.73% and 6.47% for DSC samples with ITO and FTO, respectively, both at 100 mW/$cm^2$ light intensity.

• Journal of Periodontal and Implant Science
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• 제41권6호
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• pp.263-272
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• 2011

A number of surface modification techniques using immobilization of biofunctional molecules of Titanium (Ti) for dental implants as well as surface properties of Ti and Ti alloys have been developed. The method using passive surface oxide film on titanium takes advantage of the fact that the surface film on Ti consists mainly of amorphous or low-crystalline and nonstoichiometric $TiO_2$. In another method, the reconstruction of passive films, calcium phosphate naturally forms on Ti and its alloys, which is characteristic of Ti. A third method uses the surface active hydroxyl group. The oxide surface immediately reacts with water molecules and hydroxyl groups are formed. The hydroxyl groups dissociate in aqueous solutions and show acidic and basic properties. Several additional methods are also possible, including surface modification techniques, immobilization of poly(ethylene glycol), and immobilization of biomolecules such as bone morphogenetic protein, peptide, collagen, hydrogel, and gelatin.

• 전기전자학회논문지
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• 제25권1호
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• pp.69-75
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• 2021

본 연구에서는 티타늄(Ti) 금속 박막을 사용해서 값비싼 산화주석(FTO) 전극을 대체된 염료감응형 태양전지(DSSC)의 제작 방법과 전기적 특성에 대해서 고찰하였다. Ti 박막의 증착 시간을 조절하여 박막의 두께를 변화시켰으며, Ti 박막의 두께가 두꺼워지면서 표면저항은 감소하였다. 대략 190nm 두께에서 FTO 박막의 표면저항과 비슷해짐을 알 수 있었으며, 250nm 두께에서 DSSC의 에너지 변환효율 4.24%로 가장 높았다. 더 나아가 DSSC 모듈을 제작해 평가함으로써 상용화의 가능성을 확인하였다.

• 한국응용과학기술학회지
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• 제34권4호
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• pp.705-716
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• 2017

본 연구에서는 0.5, 1.0, 1.5 wt%의 $TiO_2$를 함유하는 인듐-티타늄 수산화물을 졸 및 염기 첨가에 의해 얻었고, $200^{\circ}C$와 $500^{\circ}C$에서 겔화 과정을 통해 ITiO(Indium Titanate Oxide)를 얻었다. $200^{\circ}C$에서 겔화 과정 후 얻어지는 ITiO 입자가 작아서 조밀성이 있는 ITiO 타겟을 제조하였다. 0.5, 1.0, 1.5 wt%의 $TiO_2$를 함유하는 ITiO 타겟을 스퍼터링하여 ITiO 박막을 유리판위에 제작하여 비저항, 전하 이동도, 캐리어 농도를 조사하였다. 이들 박막 중에서 산소 조성이 0.4 %인 조건에서 0.5 wt% 중량% $TiO_2$를 함유하는 ITiO 타겟으로부터 제작된 ITiO 박막이 가장 낮은 비저항, 가장 큰 전하이동도 및 가장 낮은 캐리어 농도를 보임을 알 수 있었고, 얻어진 ITiO 박막의 광투과율을 측정하여 적외선 영역에서 광투과율이 ITO(Indium Tin Oxide) 박막에 비해 현저히 증가함을 발견하였다.

• 전기학회논문지
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• 제60권1호
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• pp.114-118
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• 2011

Dye-Sensitized Solar Cells(DSSCs) consist of a titanium dioxide($TiO_2$) nano film of the photo electrode, dye molecules on the surface of the $TiO_2$ film, an electrolyte layer and a counter electrode. But two transparent conductive oxide(TCO) substrates are estimated to be about 60[%] of the total cost of the DSSCs. Currently novel TCO-less structures have been investigated in order to reduce the cost. In this study, we suggested a TCO-less DSSCs which has titanium double layer electrodes. Titanium double layer electrodes are formed by electron-beam evaporation method. Analytical instruments such as electrochemical impedance spectroscopy, scanning electron microscope were used to evaluate the TCO-less DSSCs. As a result, the proposed structure decreases energy conversion efficiency and short-circuit current density compared with the conventional DSSCs structure with FTO glass, while internal series impedance of TCO-less DSSCs using titanium double layer electrodes decreases by 27[%]. Consequently, the fill factor is improved by 28[%] more than that of the conventional structure.