• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.425-431
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• 1999

• Journal of Powder Materials
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• v.11 no.3
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• pp.247-252
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• 2004

Recently, it has been found that mechanical alloying (MA) facilitates the nanocomposites formation of metal-metal oxide systems through solid-state reduction during ball milling. In this work, we studied the MA effect of Fe$_{3}$O$_{4}$-M (M = Al, Ti) systems, where pure metals are used as reducing agents. It is found that composite powders in which $Al_{2}$O$_{3}$ and TiO$_{2}$ are dispersed in $\alpha$-Fe matrix with nano-sized grains are obtained by mechanical alloying of Fe$_{3}$O$_{4}$ with Al and Ti for 25 and 75 hours, respectively. It is suggested that the large negative heat associated with the chemical reduction of magnetite by aluminum is responsible for the shorter MA time for composite powder formation in Fe$_{3}$O$_{4}$-Al system. X-ray diffraction results show that the reduction of magnetite by Al and Ti if a relatively simple reaction, involving one intermediate phase of FeAl$_{2}$O$_{4}$ or Fe$_{3}$Ti$_{3}$O$_{10}$. The average grain size of $\alpha$-Fe in Fe-TiO$_{2}$ composite powders is in the range of 30 nm. From magnetic measurement, we can also obtain indirect information about the details of the solid-state reduction process during MA.

• Journal of Surface Science and Engineering
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• v.25 no.5
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• pp.235-252
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• 1992

(Ti, Al)N films were deposited on 304 stainless steel sheet by D.C. magnetron sputtering using Al target and Ti plate. The high temperature oxidation of (T, Al)N films with the variation of composition has been investigated. The chemical composition of (Ti, Al)N films with the variation of composition has been investigated. The chemical composition of (Ti, Al)N films was similar to the sputter area ratio of titanium to aluminum target by means of EDS and AES survey. The high temperature oxidation test of (Ti, Al)N showed that (Ti, Al)N has better high temperature resistance than TiN and TiC films. TiC films were cracked at 40$0^{\circ}C$ in air TiN films quickly were oxidised at $600^{\circ}C$, were spalled more than $700^{\circ}C$. But (Ti, Al)N films are relatively stable to$ 900^{\circ}C$. The good resistance to high temperature oxida-tion of (Ti, Al)N films are due to the formation of dense Al2O3 and TiO2 oxide layer. Especially, Al2O3 oxide layer is more important. The results obtained from this study show, it is believe that the (Ti, Al)N film by D.C. magnetron sputtering is promising for the use of high temperature and wear resistance mate-rials.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.369-375
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• 1987

The effects of dopant Al2O3 and surface roughness on the photoelectrochemical conversion of TiO2 ceramic electrodes were investigated. The photocurrent increased with increasing the amount of dopant Al2O3 up to 0.1wt% and 0.05wt% in the specimens reduced at 700$^{\circ}C$ and 800$^{\circ}C$, respectively, and then decreased. However, the photoresponse appeared around 415 nm, which very closely corresponds to the energy band gap of TiO2(∼3.0eV), regardless of reduction temperature and the amount of Al2O3. And the photocurrent increased with increasing surface roughness in the undoped TiO2 ceramic electrode.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.313-318
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• 2001

The sliding wear behavior of Plasma-Sprayed Al$_2$O$_3$-TiO$_2$ Coating against Cemented Carbide were Investigated using a pin on disk type tester. The experiment was conducted using Al$_2$O$_3$-TiO$_2$ Coaling as pin material and Cemented Carbide as disk material and different operating conditions, at room temperature under a dry conditions. The results showed that the type B(250kw power) appeared average wear rate Is lowed than type A(80kw power). The specific wear rate of Specimen A1 Increased with normal load. But The specific wear rate of Specimen B1 decreased with normal load. Average wear rate of specimen A3, B3 are lowed than other but the sliding wear mechanism of edge were rough.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.119-120
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• 2013

공구, 다이몰드 등에 널리 쓰이는 TiC, TiN, CrN, TiCrN, TiAlN 코팅의 산화특성을 비교하기 위하여 $600^{\circ}C-900^{\circ}C$에서 대기중 산화시험을 실시하였다. 내산화성은 (TiC, TiN), TiAlN, TiCrN, CrN 코팅의 순서로 증가하였다. 코팅원소중 Ti는 $TiO_2$로, Cr은 $Cr_2O_3$로, Al은 $Al_2O_3$로 산화되었다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.110.1-110.1
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• 2012

Recently, advances in ZnO based oxide semiconductor materials have accelerated the development of thin-film transistors (TFTs), which are the building blocks for active matrix flat-panel displays including liquid crystal displays (LCD) and organic light-emitting diodes (OLED). However, the electrical performances of oxide semiconductors are significantly affected by interactions with the ambient atmosphere. Jeong et al. reported that the channel of the IGZO-TFT is very sensitive to water vapor adsorption. Thus, water vapor passivation layers are necessary for long-term current stability in the operation of the oxide-based TFTs. In the present work, $Al_2O_3$ and $TiO_2$ thin films were deposited on poly ether sulfon (PES) and $SnO_x$-based TFTs by electron cyclotron resonance atomic layer deposition (ECR-ALD). And enhancing the WVTR (water vapor transmission rate) characteristics, barrier layer structure was modified to $Al_2O_3/TiO_2$ layered structure. For example, $Al_2O_3$, $TiO_2$ single layer, $Al_2O_3/TiO_2$ double layer and $Al_2O_3/TiO_2/Al_2O_3/TiO_2$ multilayer were studied for enhancement of water vapor barrier properties. After thin film water vapor barrier deposited on PES substrate and $SnO_x$-based TFT, thin film permeation characteristics were three orders of magnitude smaller than that without water vapor barrier layer of PES substrate, stability of $SnO_x$-based TFT devices were significantly improved. Therefore, the results indicate that $Al_2O_3/TiO_2$ water vapor barrier layers are highly proper for use as a passivation layer in $SnO_x$-based TFT devices.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.635-640
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• 2016

Electrical behavior of AlN ceramics sintered with $Y_2O_3$ as a sintering aid has been investigated with respect to additional $TiO_2$ dopant. From the impedance spectroscopy, it was found that the grain and grain boundary conductivities have greatly decreased with addition of $TiO_2$ dopant. The $TiO_2$ dopant also increased the activation energy of the grain conductivity by about 0.37 eV; this increase was attributed to the formation of an associate between Al vacancies and Ti ions at the Al sites. Similarly, the electronic conductivity was reduced by $TiO_2$ addition. However, $TiO_2$ solubility in AlN grains was below the detection limit of typical EDX analysis. Grain boundary was clean, without liquid films, but did show yttrium segregation. The transference number of ions was close to 1, showing that AlN is a predominantly ionic conductor. Based on the observed results, the implications of using AlN applications as insulators have been discussed.

• Journal of the Korean Ceramic Society
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• v.38 no.7
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• pp.621-627
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• 2001

알루미나 졸에 평균 25nm의 TiO$_2$(Degussa P25) 광 촉매 분말을 분산하여 광촉매 코팅제를 제조하였다. 점도 약 24 cps를 가지 4.4 wt%의 알루미나 졸로부터 약 300nm 두께의 코팅막이 제조되었으며, 졸 점도의 증가에 비례하여 코팅막의 두께도 증가하였다. TiO$_2$광 촉매의 코팅용 바인더로 이용한 알루미나 졸의 결정형은 25~30$0^{\circ}C$에서 pseudo boehmite (AlOOH)이었으며, 50$0^{\circ}C$ 이상에서는 ${\gamma}$-Al$_2$O$_3$으로 전환되었다. AlOOH/TiO$_2$코팅막은 oleic acid와 humic acid에 대한 기상 및 수상 조건에서의 광 촉매 실험에서 우수한 유기물의 광분해 효능을 나타내었다. 아울러 EGI(Electro-Galvanized Iron)에 코팅된 AlOOH/TiO$_2$코팅막은 내식성 및 내지문성의 효과도 부수적으로 나타내었다.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.806-810
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• 2001

$La_{2/3}TiO_3$, $La_2Ti_2O_7$ are used in various parts by dielectric properties. The purpose of the present study is to understand the photoluminescence properties of $Al^{3+}\;and\;Pr^{3+}$ doped perovskite-type $La_{2/3}TiO_3$ and pyrochlore-type $La_2Ti_2O_7$ phosphor, which characterized by the red emission $(^1D_2{\rightarrow}^3H_4)\;of\;Pr^{3+}$ of $Pr^{3+}$ ion. The explanation for the energy transfer and the corresponding critical distance were proposed on the role of Al^3+ ions as energy transfer mediates in perovskite-type $La_{2/3}TiO_3$:Pr phosphor. In order to clarify the distinction of photoluminescence propoerties between the perovskite-type $La_{2/3}TiO_3$ and the pyrochlore $La_2Ti_2O_7$, the trap-involved process and the charge transfer band have been investigated.