• Macromolecular Research
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• 제16권5호
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• pp.441-445
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• 2008

A series of aluminum complexes supported by $\beta$-ketoamino, ligand-bearing, 3-position substituents $LAlEt_2$ ($L=CH_3C(O)C(Cl)=C(CH_3)NAr\;(L_1)$, $L=CH_3C(O)C(H)=C(CH_3)NAr\;(L_2)$, $L=CH_3C(O)C(Ph)=C(CH_3)NAr\;(L_3)$, and $L=CH_3C(O)C(Me)=C(CH_3)NAr\;(L_4)$, $Ar=2,6-^iPr_2C6H_3$) were synthesized in situ and employed in the ring-opening polymerization (ROP) of $\varepsilon$-caprolactone ($\varepsilon$-CL) and cyclohexene oxide (CHO). The 3-position substituents on the $\beta$-ketoamino ligand backbone of the aluminum complexes influenced the catalyst activity remarkably for both ROP of $\varepsilon$-CL and CHO. Aluminum $\beta$-ketoamino complexes displayed different catalytic behavior in ROP of $\varepsilon$-CL and CHO. The order of the catalytic activity of $LAlEt_2$ was $L_1AlEt_2$>$L_2AlEt_2$>$L_3AlEt_2$>$L_4AlEt_2$ for ROP of $\varepsilon$-CL, being opposite to the electron-donating ability of the 3-position substituents on the $\beta$-ketoamino ligand, while the order of the catalytic activity for ROP of CHO was $L_1AlEt_2$>$L_3AlEt_2$>$L_4AlEt_2$>$L_2AlEt_2$. The effects of reaction temperature and time on the ROP were also investigated for both $\varepsilon$-CL and CHO.

• 한국전기전자재료학회논문지
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• 제26권10호
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• pp.754-759
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• 2013

Aluminum oxide($Al_2O_3$) film deposited by atomic layer deposition (ALD) is known to supply excellent surface passivation properties on crystalline Si surfaces. Since $Al_2O_3$ has fixed negative charge, it forms effective surface passivation by field effect passivation on the rear side in p-type silicon solar cell. However, $Al_2O_3$ layer formed by ALD process needs very long process time, which is not applicable in mass production of silicon solar cells. In this paper, plasma-assisted ALD(PA-ALD) was applied to form $Al_2O_3$ to reduce the process time. $Al_2O_3$ synthesized by ALD on c-Si (100) wafers contains a very thin interfacial $SiO_2$ layer, which was confirmed by FTIR and TEM. To improve passivation quality of $Al_2O_3$ layer, the deposition temperature was changed in range of $150{\sim}350^{\circ}C$, then the annealing temperature and time were varied. As a result, the silicon wafer with aluminum oxide film formed in $250^{\circ}C$, $400^{\circ}C$ and 10 min for the deposition temperature, the annealing temperature and time, respectively, showed the best lifetime of 1.6ms. We also observed blistering with nanometer size during firing of $Al_2O_3$ deposited on p-type silicon.

• 한국세라믹학회지
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• 제26권2호
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• pp.276-288
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• 1989

Interpretation of high-resolution transmission electron microscopy images of defects and complex structures such as found in ceramics generally requires matching of the images with compound image simulations for reliable interpretation. A transmission electron microscopy study of the aluminum oxide was carried out at high-resolution, so that the crystal structure of the aluminum oxide could be modelled on an atomic level. In conjunction with computer simulation comparisons, the images reveal directly the atomic structure of the oxide. Results show that comparison between experimental high-resolution electron microscopy images and simulated images leads to a one to one correspondence of the image to the atomic model of the aluminum oxide. The aluminum atoms are disordered in the octahedral sites and the tetrahedral sites in the spinel aluminum oxide.

• 한국세라믹학회지
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• 제40권9호
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• pp.909-915
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• 2003

알루미늄 전해캐패시터에서 양극산화막은 유전체로서 중요한 역할을 하는데 높은 캐패시턴스를 얻기 위하여 알루미늄 위에 ZrO$_2$ 막을 졸-겔법으로 코팅하고 양극산화시킨 후 이들이 특성을 연구하였다. 코팅과 건조를 4～10회 반복하여 제조된 막들을 300～$600^{\circ}C$에서 열처리하였으며 ZrO$_2$/Al 막을 양극산화 시킨 후 ZrO$_2$/Al-ZrO$_{x}$ /Al$_2$O$_3$의 세층이 알루미늄 기판 위에 형성되었고, $Al_2$O$_3$ 층의 두께는 열처리 온도가 증가함에 따라 ZrO$_2$ 막의 치밀화로 인해 감소하였다. ZrO$_2$ 막은 30$0^{\circ}C$에서도 미세한 결정질 구조를 가지고 성장하였으며, 열처리와 양극산화 후 나타나는 알루미늄박의 캐패시턴스는 저온에서 열처리한 박이 큰 값을 보이는데 이는 ZrO$_2$ 막 자체의 캐패시턴스가 큰 것이 기인한다. 400V로 양극산화한 후 ZrO 막을 코팅한 알루미늄박의 캐패시턴스는 코팅하지 않은 경우 보다 약 3배 정도의 큰 값을 보여 복합산화물층을 갖는 알루미늄박은 알루미늄 전해캐패시터에의 적용가능성을 보였다.

• 한국결정성장학회지
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• 제8권4호
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• pp.592-598
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• 1998

ZnO($Al_2O_3\;2%$ 2% doped) 산화물 타겟과 금속 Zn(Al 2% doped) 타겟을 사용하여 반응성 직류 마그네트론 스퍼터링법으로 산소 가스 및 인가 전력을 조절하면서 AZO(Aluminum doped Zine Oxide) 막을 증착하였다. 비저항과 평균 투과율을 고려할 때 최적의 투명전도성을 보이는 조건은 산화물 타겟의 경우 산소가스의 비가 $0.5{\times}10^{-2}~1.0{\times}10^{-2}$범위이며, 금속 타겟의 경우 인가전력 0.6kW에서는 0.215~0.227, 1.0kW에서는 0.305~0.315이었다. 각 최적조건에서 제막된 AZO 막의 비저항은 $1.2~1.4{\times}10^{-3} {\Omega}{\cdot}cm$cm으로 타겟에 의한 차이는 없었다.

• Journal of Ceramic Processing Research
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• 제22권3호
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• pp.253-257
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• 2021

Among various thin film encapsulation (TFE) methods, thin films prepared by atomic layer deposition (ALD) have been shown to provide superior protection against the permeation of moisture and oxygen. This technique has numerous of advantages such as excellent uniformity, precise thickness control, and strong adhesion. Therefore, with ozone-based ALD, we conducted the influence of the thickness of aluminum oxide (Al2O3) on moisture barrier properties. From the results of an electrical calcium test, Al2O3 had two distinctly different permeation regimes. Between 10 and 25 nm of Al2O3 thickness, the water vapor transmission rate (WVTR) decreased exponentially from 6.3 × 10-3 to 1.0 × 10-4 g m-2 day-1 (1/60 times). In contrast, as thickness increased from 25 to 100 nm, the WVTR values decreased by only two-thirds, from 1.0 × 10-4 to 6.6 × 10-5 g·m-2·day-1. To better understand the change from an exponential to a sub-exponential regime, defect density and refractive index of Al2O3 were measured. The thickness dependence on defect density and refractive index was analogous with one of moisture barrier performance. These results confirmed the existence of a critical thickness at which the WVTR decreased drastically.

• 대한치과보철학회지
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• 제34권3호
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• pp.620-631
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• 1996

Bonding of resin to cast alloy has traditionally been provided by mechanical retention. But, chemical bonding methods such as silicoating, tin plating, heat treatment, application of 4-META adhesives, have been developed to overcome the problems of the mechanical bonding methods. Silicoating has been used availaby in fixed prosthodontics, but is also reported to be used in removable prosthodontics. The aim of this study is to measure the tensile bond strength between resin and metal, and compare the effect of the type of metal and the grain size of the aluminum oxide on the bond strength, after metal surface roughening, coating of the opaque resin, and curing of heat-curing resin were performed. The test groups were divided into 4 groups according to the cast alloys and the aluminum oxide particles used. Group 1 : Type 4 gold alloy(DM66) blasted with $$50{\mu}m\;Al_{2}O_3$$ Group 2 : Type 4 gold alloy(DM66) blasted with $$250{\mu}m\;Al_{2}O_3$$, Group 3 : Co-Cr alloy(Nobilium) blasted with $$50{\mu}m\;Al_{2}O_3$$ Group 4 : Co-Cr alloy(Nobilium) blasted with $$250{\mu}m\;Al_{2}O_3$$ * 10 test specimens were made on each group. The specimens were thermocycled, and Instron Universal testing machine was used to measure the tensile bond strength of the finished specimens. The results were as follows : 1. Bond strengths showed that the group of gold alloy blasted with $250{\mu}m$ aluminum oxide particle had higher bond strength, and the group of gold alloy blasted with $50{\mu}m$ aluminum oxide particles had lower bond strength than any of the other groups. 2. Gold alloy had significantly higher bond strength when blasted with $250{\mu}m$ aluminum oxide particles than $50{\mu}m$, but. Co-Cr alloy showed no statistically significant difference between the two particle sizes. 3. When blasted with $50{mu}m$ aluminum oxide particles, Co-Cr alloy showed significantly higher bond strength than gold alloy. And, when blasted with $250{\mu}m$ aluminum oxide particles, gold alloy had significantly higher bond strength than Co-Cr alloy. 4. On the examination of the fractured sites, only the group of Co-Cr alloy blasted with $50{\mu}m$ aluminum oxide particles showed a part of residual opaque resin, but all the samples of the other groups fractured between the resin and the metal.

• 한국표면공학회지
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• 제55권5호
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• pp.273-283
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• 2022

Al6061 aluminum alloy specimens were exposed to atmospheric conditions for maximum 24 months. 24-month exposure specimen showed some more frequent and larger size of corrosion products and pitting on the surface compared with the 12-month exposure specimens. The XRD examination revealed the dominant surface oxide phases of Al₂O₃ and Al(OH)₃. The oxide thickness at uniform oxidation (or non-pitting) region was not much changed over exposure time. The 1.2 ㎛ deep oxygen penetration area was found in the 12-months exposed specimen near the thin uniform aluminum oxide film. The line-EDS was conducted through the penetration regions and non-penetrated grain boundary. There were signs of O and Si concentration through the penetration region, whereas non-penetration region showed no concentration of O or Si. It was confirmed that pitting is a more severe degradation mode in Al6061 (max. >4 ㎛ deep) compared with the uniform oxidation (max. ~200 nm deep) up to 24-months exposure.

• 동력기계공학회지
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• 제20권3호
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• pp.17-21
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• 2016

The corrosion behavior of aluminum alloys in the $H_2SO_4$ solution was investigated based on potentiodynamic techniques. Electrochemical properties, such as corrosion potential($E_c$), passive potential($E_p$), corrosion current density($I_c$), corrosion rate(mpy), of Al-Mg-Si, Al-Cu-Si and Al-Si alloys were characterized at room temperature. Passive aluminum oxide film, which including $Al_2(SO_4)_3$ and $3Al_2O_34SO_38H_2O$, were uniformly formed on the surface via the reaction of Al with $SO{_3}^{2-}$ or $SO{_4}^{2-}$ ions in the $H_2SO_4$ solution and the dependence of the corrosion behavior on the alloying element was discussed. The selective leaching of alloy element increased with increasing Cu content in the aluminum alloys.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.114-114
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• 2012

Metal-oxide-semiconductor field-effect transistors (MOSFETs)의 critical dimension (CD)가 sub 45 nm로 줄어듬에 따라 기존에 gate dielectric으로 사용하고 있는 SiO2에서 발생되는 high gate leakage current 때문에 새로운 high dielectric constant (k) 물질들이 연구되기 시작하였다. 여러 가지 high-k 물질 중에서, aluminum-oxide (Al2O3)는 높은 dielectric constant (~10)와 전자 터널링 barrier height (~2eV) 등을 가지기 때문에 많은 연구가 되고 있다. 그러나 Al2O3를 anisotropic한 patterning을 하기 위해 주로 사용되고 있는 halogen-based 플라즈마 식각 과정에서 나타나는 Al2O3와 하부 layer간의 낮은 식각 selectivity 뿐만 아니라 표면에 발생되는 defect, stoichiometry modification, roughness 변화 등의 많은 문제점들로 인하여 device performance가 감소하기 때문에 이를 해결하기 위한 많은 연구들이 진행중이다. 따라서 본 연구에서는 실리콘 기판위의 atomic layer deposition (ALD)로 증착된 Al2O3를 BCl3/Ar 중성빔을 이용하여 원자층 식각한 후 식각 특성을 분석해 보았다. Al2O3 표면을 BCl3로 absorption시킨 후 Ar 중성빔으로 desorption 시키는 과정에서 volatile한 aluminum-chlorides와 boron oxychloride가 형성되어 layer by layer로 제거됨을 관찰 할 수 있었다.