• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
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• pp.45.1-45
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• 2002

• 한국결정성장학회지
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• 제24권5호
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• pp.213-218
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• 2014

Anatase $TiO_2$에 각기 다른 텅스텐(W) 함유원료와 제조방법을 적용하여 $WO_3$ 촉매가 첨가된 SCR(selective catalytic reduction)용 분말을 합성하였으며, W 촉매 첨가가 합성분말의 상합성 및 SCR 촉매능에 미치는 영향에 대해 연구하였다. 촉매의 지지체인 $TiO_2$는 침전법으로 anatase 상으로 합성되었으며, anatase에서 고온상인 rutile로의 상전이 온도는 $1200^{\circ}C$였으나, $WO_3$를 10 wt% 첨가할 경우 이 상전이 온도는 $900^{\circ}C$로 낮아졌다. 건식으로 $WO_3$ 분말을 직접 첨가하여 $WO_3(10wt%)/TiO_2$를 제조한 경우 $350^{\circ}C$에서 $NO_X$ 제거 촉매능이 최고점에 이르나 온도증가에 따라 그 효율이 상당히 감소하였다. 암모늄-메타-텅스테이트를 습식으로 첨가하여 제조한 경우, 보다 고온인 $450^{\circ}C$에서 촉매능이 최고점에 이르렀으며 온도에 따른 효율감소 폭도 적었다. 이와 같은 경향은 $WO_3$와 $V_2O_5$를 동시 첨가하여 제조한 $V_2O_5(5wt%)-WO_3(10wt%)/TiO_2$ 촉매에서도 나타났다. 즉, 암모늄-메타-텅스테이트를 습식으로 첨가한 경우, $WO_3$를 직접 첨가한 경우에 비해 넓은 온도범위($300^{\circ}C{\sim}500^{\circ}C$)에 걸쳐 90 %에 이상의 우수한 $NO_X$ 변환효율을 보였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.51-54
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• 2000

In this paper, $Ba_{0.5}$Sr$_{0.5}$TiO$_3$ thin films were prepared on Pt/Ti/SiO$_2$/Si substrate by RF magnetron sputtering method. We investigated effect of deposition conditions (especially RF input power) on structural properties of BST thin films. Deposit conditions of BST films were set working gas ratio, Ar:O$_2$= 70 : 30, working pressure 10mTorr, and RF input power 25W, 50W, 75W and 100W. Post-annealing using rapid thermal annealing(RTA) performed at 45$0^{\circ}C$, 55$0^{\circ}C$, $650^{\circ}C$, and 75$0^{\circ}C$ in oxigen ambient for 60 sec, respectively. The structural properties of BST films on Pt/Ti/SiO$_2$/Si substrate analysed by X-ray diffraction(XRD).).).

• 한국재료학회지
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• 제9권1호
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• pp.57-64
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• 1999

The electrical conductivity of TiO$_2$ doped with 0.05~1.5mol% WO$_3$ was measured in the oxygen partial pressure range of 10\ulcorner~10\ulcorner atm and temperature range of 1100~130$0^{\circ}C$ to investigate the defect types and the electrical properties. The grain size and density were increased as the liquid phase was formed by the doped WO$_3$. The secondary phase and WO$_3$peaks at the sample doped up to 4.0 mol% were not detected from the XRD results. The data(log$\sigma$/logPo$_2$) over 110$0^{\circ}C$ were divided into the four regions. From these experimental results, we proposed the following defect regions. 1) Magneli phase(extended defect), 2) Reduced rutile region which is similar to the behavior of undoped rutile, 3) Nearly stoichiometric Ti\ulcornerW\ulcornerO$_2$region in which extra charge of W\ulcorner cation is expected to be compensated by an electron, 4) Overstoichiometric Ti\ulcornerW\ulcornerO\ulcorner region which is a metal deficiency not to be observed in pure TiO$_2$. The electrical conductivity of w-doped TiO$_2$ was influenced by the measuring temperature, oxygen partial pressure, and the dopig content.

• 한국전기전자재료학회논문지
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• 제16권5호
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• pp.397-403
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• 2003

Microwave dielectric properties of (1-x)ZnW $O_4$-xTi $O_2$ ceramic systems were investigated with calcination temperatures and Ti $O_2$ contents. The ZnW $O_4$ ceramic could be suitably sintered at 1075$^{\circ}C$ and showed the dielectric constant of 13.6, quality factor(Q$\times$ $f_{O}$value) of 22,000 and temperature coefficient of resonant frequency($\tau$$_{f}$) of -65$\pm$2ppm/$^{\circ}C$. Increasing the amount of Ti $O_2$ in the range of 0.25 to 0.45 mol, the dielectric constant and $\tau$$_{f}$ increased due to the role of Ti $O_2$ but the quality factor decreased due to the increase of phase boundaries. The 0.7ZnW $O_4$-0.3Ti $O_2$ ceramic showed the dielectric constant of 19.8, qualify factor(Q$\times$ $f_{0}$) of 20,000 and $\tau$$_{f}$ of -3$\pm$1ppm/$^{\circ}C$.>.EX>.>.>.

• 한국분말재료학회지
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• 제24권6호
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• pp.472-476
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• 2017

Porous W-10 wt% Ti alloys are prepared by freeze-drying a $WO_3-TiH_2$/camphene slurry, using a sintering process. X-ray diffraction analysis of the heat-treated powder in an argon atmosphere shows the $WO_3$ peak of the starting powder and reaction-phase peaks such as $WO_{2.9}$, $WO_2$, and $TiO_2$ peaks. In contrast, a powder mixture heated in a hydrogen atmosphere is composed of the W and TiW phases. The formation of reaction phases that are dependent on the atmosphere is explained by a thermodynamic consideration of the reduction behavior of $WO_3$ and the dehydrogenation reaction of $TiH_2$. To fabricate a porous W-Ti alloy, the camphene slurry is frozen at $-30^{\circ}C$, and pores are generated in the frozen specimens by the sublimation of camphene while drying in air. The green body is hydrogen-reduced and sintered at $1000^{\circ}C$ for 1 h. The sintered sample prepared by freeze-drying the camphene slurry shows large and aligned parallel pores in the camphene growth direction, and small pores in the internal walls of the large pores. The strut between large pores consists of very fine particles with partial necking between them.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.288-291
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• 1996

The surface properties after plasma etching of TiW solutions using the chemistries of BCl$_3$ and SF$\_$6/ gases with varying mixing ratio have been investigated using X-ray photoelectron spectroscopy. The elements of C, Cl, F, O and S are observed on the etched TiW films. After plasma etching with SF$\_$6/ gas, Ti-S bond are detected on the samples and Ti-S bond makes a role of passivation layer that surpresses Ti-O formation. After plasma etching wish BCl$_3$ gas, Ti are easily removed but W are hardly etched. As a results, W/Ti are increased on the etched sample.

• 한국세라믹학회지
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• 제37권11호
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• pp.1065-1070
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• 2000

TiO$_2$의 첨가가 Mn-Zn ferrites의 전자기적 물성에 미치는 효과에 대해 연구하였다. TiO$_2$의 첨가량이 증가함에 따라 밀도와 전기비저항이 증가된 반면 초기투자율은 감소하였다. TiO$_2$의 첨가에 따라 Fe$^{2+}$ ion의 증가에 기인하여 전력손실의 최소 값을 나타내는 온도가 저온으로 이동하였다. TiO$_2$를 0.12wt% 첨가한 시편의 경우, 100 kHz, 200 mT, 8$0^{\circ}C$ 측정 조건에서는 소결온도가 증가함에 따라 전력손실이 감소하였으며 125$0^{\circ}C$ 소결한 시편이 340 mW/㎤으로 가장 낮은 값을 보였다. 500 kHz, 50 mT, 8$0^{\circ}C$의 측정 조건에서는 소결 온도가 감소함에 따라 전력손실이 감소하였으며 115$0^{\circ}C$ 소결한 시편이 105 mW/㎤으로 가장 낮은 전력손실 값이 관찰되었다.

• 공업화학
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• 제26권6호
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• pp.666-673
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• 2015

본 연구에서는 고온영역에서 NOx를 제어하기 위한 선택적 환원촉매(SCR)의 연구를 수행하였다. 제조된 촉매들의 구조적 특성 및 흡 탈착 특성을 확인하기 위하여 XRD, FT-IR 분석을 수행하였다. Anatase $TiO_2$ 지지체의 경우 미미한 NOx 전환율을 나타내었으며, 이에 W을 활성금속으로 하여 제조한 $W/TiO_2$ 촉매에서 우수한 NOx 제거 능력을 보였다. 특히 $400^{\circ}C$ 이상의 고온영역에서 순수 $TiO_2$의 NOx 전환율보다 W이 함유된 $W/TiO_2$의 촉매에서 급격한 활성 증가를 확인할 수 있었다. 또한, 장시간의 열충격에 따른 반응활성이 감소되는 현상이 억제됨을 확인하였다.

• 열처리공학회지
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• 제17권4호
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• pp.236-240
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• 2004

Effect of plasma power on PECVD process were investigated in this study. TiN and TiCN films were deposited on nitrided STD11 steel with 600W, 1,200W and 1,600W plasma power. As the plasma power was increased, the preferred orientation was reinforced from (200) to (111) and the hardness of films was improved. The low plasma power was, however, effective for improving of adhesion force of films. Regarding above properties, TiN and TiCN films were deposited by gradient plasma power. It was possible to get high hardness as well as adhesion force through gradient plasma power.