• Journal of the Korean Ceramic Society
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• v.29 no.6
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• pp.419-430
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• 1992

Fabrication possibility of low-shrinkage alumina without oxidation and wetting agent was presented on the basis of observation about oxidation behavior, microstructure and physical characteristics of such reaction agents free Al2O3-Al system. The composition less than Al 10w/o where Al can act as a sintering agent for Al2O3 was excluded. Under the condition of present experiments oxidation of Al2O3-Al system was dependent not on holding time but mainly on oxidation temperature. In thes case of Al powder not comminuted effectively during powder mixing of Al2O3-Al, columnar structure which would act as a hindrance to the densification during sintering developed more during oxidation with higher Al contents, and which made the fabrication of low-shrinkage Al2O3 ceramics impossible. If Al powder was comminuted effectively due to co-mixed Al2O3 characteristics, densification was improved because of no columnar structure and made the fabrication of sintered body with -2.7% dimensional change and 81% relative density possible. As a result, it is possible to fabricate dense low-shrinkage Al2O3 ceramics without oxidation and wetting agent under conditions such as smaller particle size of Al, Al contents below 50v/o, higher green density of Al2O3-Al compact and the use of Al2O3 powder used for high-density ceramics.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.47-52
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• 1996

Cl-based gas chemistry is generally used to etching for al alloy metallization. After the etching of Al alloy with Cl-based gas plasma, residual chlorine on Al alloy reacts with H$_{2}$O due to air exposure and results in Al corrosion. In this study, the corrosion phenomena of Al wer examined with XPS(X-ray photoelectron spectroscopy) and SEM (scanning electorn microscopy). It was confirmed that chlorine mainly existed at the grian boundary of Al alloy after plasma etching of Al alloy with cl-based gas chemistry and Al corrosion was largely generated at the grain boundary of Al alloy. And residual chlorine was passivated by sulfur and fluorine which were generated by SF$_{6}$ plasma. These effects of passivation reduced the Al corrosion due to air exposure.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.54-54
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• 2014

전자빔 증착을 이용하여 알루미늄(Al)과 마그네슘(Mg)의 2층 구조를 갖는 박막을 강판 위에 코팅한 후 열처리를 실시하여 박막의 미세구조 변화와 합금상을 관찰하고 Al-Mg 코팅 강판의 내부식 특성을 평가하였다. 이를 통해서 Al-Mg 박막의 미세구조와 합금상이 Al-Mg 코팅 강판의 내부식 특성에 미치는 영향을 확인하였다. Al-Mg 박막의 조성은 Al 박막과 Mg 박막의 두께 변화를 이용하여 조절하였으며 Al-Mg 박막의 두께비는 각각 1:1(Al:Mg), 2:1, 5:1 이었다. 열처리 온도는 $400^{\circ}C$, 열처리 시간은 2, 3, 10분 이었다. Al-Mg 코팅 강판은 열처리를 실시하면 주상구조에서 치밀한 구조로 변화하였으며 Al-Mg 합금상이 생성되었으며 합금상은 $Al_3Mg_2$와 $Al_{12}Mg_{17} $ 이었다. 이러한 합금상의 생성으로 Al-Mg 박막의 미세구조가 변화하고 Al-Mg 코팅 강판의 내식성에도 영향을 미친 것으로 판단된다.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.642-648
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• 2011

This paper describes an experimental study on ultrasonic welding of similar and dissimilar metals. There are optimum welding conditions which are found for welding of Al/Al and Al/Cu. It evaluated weldability using tensile test, SEM observation and EDX-ray analysis. Both ultrasonic welding of Al/Al and Al/Cu have amplitude as the variable factor. Al/Cu welding was examined again with welding time as variable factor to find the best conditions. The more welding time or amplitude increase, the better weldability. The optimum conditions for ultrasonic welding of Al/Al were formed at pressure 0.25 MPa, welding time 0.25 sec, amplitude 90%. Pressure 0.25 MPa, welding time 0.4 sec, amplitude 80% are optimized for Al/Cu ultrasonic metal welding and solid-state diffusion generated by ultrasonic vibration and frictional heat is confirmed at the welded interface.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.58-65
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• 2010

AlN thin films were deposited on sapphire substrates and ZnO templates by rf-magnetron sputtering. Powder-sintered AlN target was adopted for source material. Thickness of AlN layer was linearly dependent on plasma power from 50 to 110 W, and it decreased slightly when working pressure increased from 3 to 10 mTorr due to short mean free path of source material sputtered from AlN target by Ar working gas. When $N_2$ gas was mixed with Ar, the thickness of AlN layer decreased significantly because of low sputter yield of nitrogen. AlN layer was also deposited on ZnO template. However, it showed weak thermal stability that the interface between AlN and ZnO was deteriorated by rapid thermal annealing treatment above $700^{\circ}C$. In addition, ZnO layer was largely attacked by MOCVD ambient gas of hydrogen and ammonia around $700^{\circ}C$ through inferior AlN layer deposited by sputtering. And AlN layers were fully peeled off above $900^{\circ}C$.

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.558-563
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• 2008

TiAlN films were deposited on WC-5Co substrates with different buffer layers by D.C. magnetron sputtering. The films were evaluated by microstructural observations and measuring of preferred orientation, hardness value, and adhesion force. As a process variable, various buffer layers were used such as TiAlN single layer, TiAlN/TiAl, TiAlN/TiN and TiAlN/CrN. TiAlN coating layer showed columnar structures which grew up at a right angle to the substrates. The thickness of the TiAlN coating layer was about $1.8{\mu}m$, which was formed for 200 minutes at $300^{\circ}$. XRD analysis showed that the preferred orientation of TiAlN layer with TiN buffer layer was (111) and (200), and the specimens of TiAlN/TiAl, TiAlN/CrN, TiAlN single layer have preferred orientation of (111), respectively. TiAlN single layer and TiAlN/TiAl showed good adhesion properties, showing an over 80N adhesion force, while TiAlN/TiN film showed approximately 13N and the TiAlN/CrN was the worst case, in which the layer was destroyed because of high internal residual stress. The value of micro vickers hardness of the TiAlN single layer, TiAlN/TiAl and TiAlN/TiN layers were 2711, 2548 and 2461 Hv, respectively.

• Journal of Korea Foundry Society
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• v.27 no.6
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• pp.250-254
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• 2007

3원계 Al-Nb-Zr의 용응 합금을 스프렛 ?봬?(splat-quenching) 방법을 이용하여 급속냉각응고 한 후, 응고된 시편을 698K에서 200시간까지 열처리하여 상전이를 연구하였다. 급속응고 및 열처리된 시편의 미세구조는 X-선 회절 및 투과전자 현미경으로 분석하였다. Al-1.95Nb-0.65Zr, Al-1.3Nb-1.3Zr, 및 Al-0.65Nb-1.95Zr (at%) 3원 합금계를 연구하였다. 각 합금의 조성은 Vegard's 법칙을 적용하여 Al(${\alpha}$)의 기지조직과 $L1_2-Al_3(Nb,Zr)$의 석출상들이 정합을 이루도록 선택되었다. 급속응고된 후 각 합금은 과고용된 Al(${\alpha}$)의 고용상을 형성하였다. Al-1.3Nb-1.3Zr, 및 Al-0.65Nb-1.95Zr의 급속응고된 상태의 시편을 698K에서 열처리하여 알루미늄 기지와 정합의 계면을 갖는 $L1_2-Al_3(Nb_{0.5}Zr_{0.5})$와 $L1_2-Al_3(Nb_{0.25}Zr_{0.75})$의 상을 각각 석출하였다. 반면 Al-1.95Nb-0.65Zr 합금은 평형상인 $D0_{22}-Al_3(Nb_{0.75}Zr_{0.25})$ 상을 석출하였다. 준안정상의 정합 $Al_3(Nb,Zr)$ 미세 분산상 석출은 입자의 조대화를 억제하고 재료의 고온 강도를 증가될 것으로 사료된다.

• Journal of the Korean institute of surface engineering
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• v.41 no.6
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• pp.325-330
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• 2008

Al6061 and Sus304 materials are bonded by using thermal bonding technology. Al6061, Sus304 and thermal bonded Al6061/Al6061 and Al6061/Sus304 materials are characterized by using mechanical and electrical measurement. Especially the experimental characteristic data of thermal bonded Al6061/Al6061 and Al6061/Sus304 are not well known until today. We have investigated on Al6061, Sus304 and thermal bonded material. The thermal bonded material Al6061/Al6061 and Al6061/Sus304 can be used for the LCD frame and the other electrical products. For the future, we expect that the more various experiments should be needed to carry out for the data accumulation in the bonded new materials.

• Korean Journal of Materials Research
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• v.22 no.2
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• pp.97-102
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• 2012

The microstructure and tensile properties of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duocasting were investigated. Only the Al-Mn alloy showed the typical cast microstructure of columnar and equiaxed crystals. The primary dendrites and eutectic structure were clearly observed in the Al-Si alloy. There existed a macro-interface of Al-Mn/Al-Si alloys in the hybrid aluminum alloys. The macro-interface was well bonded, and the growth of primary dendrites in Al-Si alloy occurred from the macro-interface. The Al-Mn/Al-Si hybrid aluminum alloys with a well-bonded macro-interface showed excellent tensile strength and 0.2% proof stress, both of which are comparable to those values for binary Al-Mn alloy, indicating that the strength is preferentially dominated by the deformation of the Al-Mn alloy side. However, the degree of elongation was between that of binary Al-Mn and Al-Si alloys. The Al-Mn/Al-Si hybrid aluminum alloys were fractured on the Al-Mn alloy side. This was considered to have resulted from the limited deformation in the Al-Mn alloy side, which led to relatively low elongation compared to the binary Al-Mn alloy.

• Korean Journal of Materials Research
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• v.11 no.1
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• pp.34-38
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• 2001

Intermetallics of Fe-28%Al($Fe_3Al$) and Fe-28%Al-4%Cr($Fe_3Al-4Cr$) were oxidized at 1073, 1273 and 1473k in air for up to 17 days. The oxidation resistance of$Fe_3Al-4Cr$ was basically similar to or better than that of $Fe_3Al$. The oxide scales formed on $Fe_3Al$ consisted essentially of pure ${\alpha}-AL_2O_3$, while those formed on $Fe_3Al-4Cr$ consisted of ${\alpha}-AL_2O_3$ having dissolved iron and chromium ions. The preferential outward diffusion of substrate elements to form the outer oxide layer led to the formation of Kirkendall voids at the oxide-matrix interface. The scales formed on $Fe_3Al(-4Cr)$ were thin and dense up to 1273K, but they spalled easily at 1473K, accompanied by more weight gains.