• 마이크로전자및패키징학회지
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• 제25권2호
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• pp.9-17
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• 2018

Aluminum (Al) and its alloys have been used widely in a variety of industries such as structural, electronic, aerospace, and particularly automotive industries due to their lightweight characteristic, outstanding ductility, formability, high oxidation and corrosion resistance, and high thermal and electrical conductivity. Al have different kinds of alloys according to the various additional elements system and they should be selected properly depending on their effectiveness and suitability for their particular purpose. The major elements for Al alloys are silicon (Si), magnesium (Mg), manganese (Mn), copper (Cu), and zinc (Zn). In order for Al alloys to use for each industry, it is necessary to study of Al to Al joining and/or the Al to dissimilar materials joining to combine the individual parts into one. Many studies on joining technologies about Al to Al and Al to dissimilar materials have been performed such as press joining, bolted joint, welding, soldering, riveting, adhesive bonding, and brazing. This study reviews a variety of Al alloys and their joining method including its principles and properties with recent trends.

• 한국주조공학회지
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• 제25권2호
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• pp.80-87
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• 2005

The microstructure and mechanical property of the Ni and Ni-Cr porous metal reinforced AC4C matrix composites fabricated by squeeze casting were investigated. In this study Ni, Ni-Cr porous metals which are estimated to be easy to fabricate by squeeze casting are used as strengtheners for composite materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Ni/AC4C and Ni-Cr/AC4C composite, $750^{\circ}C$ melt temperature and minimum 25MPa squeezing pressure are needed to produce sound composite materials. The observation of interfacial reaction zone at various heat treatment condition shows that atsolutionizing temperature of above $520^{\circ}C$, the interfacial reaction zone increases proportionally with heat treatment time and the reaction products formed by interfacial reactions are mainly composed by $Al_{3}Ni$ and $Al_{3}Ni_{2}$ phases.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.189-190
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• 2011

Cu가 기존 배선물질인 Al을 대체함에 따라 resistance-capacitance (RC) delay나 electromigration (EM) 등의 문제들이 어느 정도 해결되었다. 그러나 지속적인 배선 폭의 감소로 배선의 저항 증가, EM 현상 강화 그리고 stability 악화 등의 문제가 지속적으로 야기되고 있다. 이를 해결하기 위한 방법으로 Cu alloy seed layer를 이용한 barrier 자가형성 공정에 대한 연구를 진행하였다. 이 공정은 Cu 합금을 seed layer로 사용하여 도금을 한 후 열처리를 통해 SiO2와의 계면에서 barrier를 자가 형성시키는 공정이다. 이 공정은 매우 균일하고 얇은 barrier를 형성할 수 있고 별도의 barrier와 glue layer를 형성하지 않아 seed layer를 위한 공간을 추가로 확보할 수 있는 장점을 가지고 있다. 또한, via bottom에 barrier가 형성되지 않아 배선 전체 저항을 급격히 낮출 수 있다. 합금 물질로는 초기 Al이나 Mg에 대한 연구가 진행되었으나, 낮은 oxide formation energy로 인해 SiO2에 과도한 손상을 주는 문제점이 제기되었다. 최근 Mn을 합금 물질로 사용한 안정적인 barrier 형성 공정이 보고 되고 있다. 하지만, barrier 형성을 하기 위해 300도 이상의 열처리 온도가 필요하고 열처리 시간 또한 긴 단점이 있다. 본 실험에서는 co-sputtering system을 사용하여 Cu-V 합금을 형성하였고, barrier를 자가 형성을 위해 300도에서 500도까지 열처리 온도를 변화시키며 1시간 동안 열처리를 실시하였다. Cu-V 공정 조건 확립을 위해 AFM, XRD, 4-point probe system을 이용하여 표면 거칠기, 결정성과 비저항을 평가하였다. Cu-V 박막 내 V의 함량은 V target의 plasma power density를 변화시켜 조절 하였으며 XPS를 통해 분석하였다. 열처리 후 시편의 단면을 TEM으로 분석하여 Cu-V 박막과 SiO2 사이에 interlayer가 형성된 것을 확인 하였으며 EDS를 이용한 element mapping을 통해 Cu-V 내 V의 거동과 interlayer의 성분을 확인하였다. PVD Cu-V 박막은 기판 온도에 큰 영향을 받았고, 200 도 이상에서는 Cu의 높은 표면에너지에 의한 agglomeration 현상으로 거친 표면을 가지는 박막이 형성되었다. 7.61 at.%의 V함량을 가지는 Cu-V 박막을 300도에서 1시간 열처리 한 결과 4.5 nm의 V based oxide interlayer가 형성된 것을 확인하였다. 열처리에 의해 Cu-V 박막 내 V은 SiO2와의 계면과 박막 표면으로 확산하며 oxide를 형성했으며 Cu-V 박막 내 V 함량은 줄어들었다. 300, 400, 500도에서 열처리 한 결과 동일 조성과 열처리 온도에서 Cu-Mn에 의해 형성된 interlayer의 두께 보다 두껍게 성장 했다. 이는 V의 oxide formation nergyrk Mn 보다 작으므로 SiO2와의 계면에서 산화막 형성이 쉽기 때문으로 판단된다. 또한, V+5 이온 반경이 Mn+2 이온 반경보다 작아 oxide 내부에서 확산이 용이하며 oxide 박막 내에 여기되는 전기장이 더 큰 산화수를 가지는 V의 경우 더 크기 때문으로 판단된다.

• 대한금속재료학회지
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• 제50권7호
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• pp.503-509
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• 2012

We report on the feasibility of producing 6xxx series Al alloy sheets using a combination of twin-roll strip casting and asymmetric rolling. The Al alloy sheets produced in this study exhibited an excellent formability ($\bar{r}=1.2$, ${\Delta}r=0.17$) and mechanical properties (${\sigma}_{TS}{\sim}260MPa$, ${\varepsilon}>30%$), which cannot be feasibly obtained via the conventional technique based on ingot casting and conventional rolling. The enhanced formability as evaluated in terms of $\bar{r}$ and ${\Delta}r$ was clarified by examining the evolution of textures associated with strip casting and subsequent thermo-mechanical treatments. The evaluation of the formability leads us to conclude that the combined technique based on strip casting and asymmetric rolling is a feasible process for enhancing the formability of Al alloy sheets to a level beyond which the conventional technique can reach.

• 한국주조공학회지
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• 제28권1호
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• pp.20-24
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• 2008

The characteristics, such as roughness, thickness, microhardness and corrosion resistance, of plasma electrolytic oxide coatings on AZ91D alloy were investigated under the processing condition of various coating times. The coatings on AZ91D alloy consisted of MgO, $MgAl_{2}O_{4}$ and $Mg_{2}SiO_{4}$ oxides. The surface roughness and thickness of coatings became larger with increasing the coating time. The microhardness in cross section of coatings was much higher than not only that in surface but that in the conventional anodic oxide coatings, which increased progressively as the coating time increased. After being immersed in 3.5%NaCl solution and methyl alcohol, the corrosion resistance of AZ91D alloy was markedly improved by plasma electrolytic oxidation coating treatment, and the AZ91D alloy coated for 50min revealed excellent corrosion resistance.

• Journal of Welding and Joining
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• 제22권5호
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• pp.65-72
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• 2004

The tendency and degree of hot cracking of high strength 5083, 6N01 and 7N01 Al alloy welds by using DCSP-GTAW through modified Varestraint test and autogenous butt welding were investigated. In hot cracking test, 6N01 alloy showed the highest susceptibility to hot cracking in the weld metal and HAZ. Cracking susceptibilities generally increased with increase of solidification temperature range of the base metal and bead penetration-to-width ratio of the weld metal. The cracks in welds of the alloys vertically formed to solid-liquid interface and propagated along with columnar grain boundaries. The fracture facets of cracks showed the typical morphology of solidification crack observed as dendritic structures. Especially, in 6N01 alloy, liquation cracks which were due to elements of Si, Fe and Mg also observed in HAZ near fusion boundary. In butt welding of different Al alloys, the bead crack was mainly occurred in the welds of 6N01, 7N01 and other Al alloys together with 6N01 or 7N01. In the butt welds of 7N01, it was found that the component of Cu had an effect on the higher susceptibility to the hot cracking.

• 한국표면공학회지
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• 제54권2호
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• pp.62-70
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• 2021

Al2024 aluminum alloy specimens were exposed to atmospheric conditions for maximum 24 months and analyzed by electron microscopes to characterize their corrosion behavior and oxide film characteristics. As the exposure time increased from 12 months to 24 months, the number of pitting sites per 1 mm² increased from ~100 to ~200. The uniform oxidation (or non-pitting) region of the 12-month exposure specimen showed 30~120 nm thick oxide layer, whereas the 24-month exposure specimen showed 170~200 nm thick oxide with the local oxygen penetration region up to 1 ㎛ deep. There was no local corrosion area observed in the 12-month exposure specimen except pitting. However, in the 24-month exposure specimen, local oxygen penetration region was observed beneath the uniform oxide layer and near the pitting cavity. Al2024 showed two times thicker uniform oxide layer but much shallower local oxygen penetration region than Al1050, which appears to be related to low Si concentration. Further research is needed on the effects of Mg segregation near the tip of the oxygen penetration region.

• Composites Research
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• 제21권6호
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• pp.8-14
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• 2008

가로등은 운전자의 안전을 위한 필수적인 도로 부속구조물이며, 대부분 강재 등주를 사용하고 있다. 강재등주는 부식이 발생하여 내구성을 감소시키고, 도시미관을 저해하므로 스테인레스 제품이나 주철재 등을 사용하기도 한다. 그러나 주철재 및 스테인레스 등주를 사용하더라도 부식에 대한 위험성을 완전히 배제할 수 없고, 높은 강도와 강성은 충돌시 운전자의 안전을 위협하는 요인이 되고 있다. 따라서 새로운 형태의 등주 시스템의 개발이 요구되고 있다. 기존 등주의 문제점을 보완하기 위해 최근 알루미늄 합금을 사용한 등주가 개발되어 사용되고 있다. 알루미늄은 재료적 특성상 단위중량당 강도가 높고 부식에 대한 저항성이 매우 커서 그 활용성을 크게 증대될 것으로 예측되나 강계에 비해 강성과 강도가 낮기 때문에 구조적 안전성에서 문제점이 제기되고 있어 구조거동에 대한 연구가 필요하다. 이 연구는 현재 가로등 등주로 사용되고 있는 강재 및 알루미늄 등주에 대한 휨, 압축실험 등을 수행하여 알루미늄 등주의 구조거동을 조사하였고, 기존 강재등주와 비교하여 효율성 및 안전성을 평가하였다.

• 한국주조공학회지
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• 제8권3호
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• pp.282-286
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• 1988

Aluminum alloy permanent mold castings often exhibit in as-cast or T5-heat treated state an inverse distribution of hardness, i.e. thinner sections have lower hardness than thicker sections. This phenomina is explained by measuring the cooling curves in a test casting in an Aluminum piston alloy (AC8A or A332). Thinner sections solidify faster but later cooles down more slowly than thicker sections in temperature range where coarse precipitation of supersaturated elements can take place. The precipitation rate of $Mg_2Si$ phase in A332 alloy seems to be maximum at around $490^{\circ}C$.

• 한국주조공학회지
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• 제25권2호
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• pp.88-94
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• 2005

The microstructure and mechanical property of the ceramic reinforced AC4C matrix composites processed by squeeze casting were investigated. In this study Kaowool and Saffil fiber which are ceramic reinforcements are used as preform materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Kaowool and Saffil/AC4C composites, 7.5 MPa squeezing pressure and minimum 7.0% binder amount are needed to produce sound composite materials. The tensile strength of Kaowool/ AC4C composite is lower than the matrix metal and this can be explained by the melt unfilling due to formed cluster of Kaowool reinforcements. But the mechanical properties of hardness, wear resistance and thermal expansion are better than the matrix materials due to the strengthening effect of ceramic reinforcements.