• Journal of the Korean Chemical Society
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• v.40 no.3
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• pp.202-208
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• 1996

SAPO-11 was synthesized hydrothermally and dealuminated with $H_4$EDTA. The framework structure of SAPO-11 was maintained safely by 24 hours' dealumination, but further dealumination for 48 hours caused SAPO-11 collapsed and to be changed to variscite($AIPO_4{\cdot}2H_2O$) and tridymite($SiO_2$). Dealuminated SAPO-11 showed two structural hydroxyl bands at 3607 $cm^{-1}$ and 3453 $cm^{-1}$ respectively. The intensities of these two bands increased according to the extent of dealumination, and disappeared by the adsorption of methylamine. Dealuminated SAPO-11 showed higher desorption temperatures and greater activation energies in desorption of water and methylamine compared to non-dealuminated SAPO-11. All the phenomena may be due to the stronger interactions of Bronsted acid sites of structural hydroxyl groups generated by dealumination with adsorbed water and methylamine molecules respectively.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.617-619
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• 2012

본 논문에서는 알루미늄 폼 복합재료로 된 DCB(이중외팔보) 구조체의 파괴 거동을 시뮬레이션 해석하였다. 시뮬레이션 해석에 사용된 모델은 영국 공업규격과 ISO국제규격에 의거하여 3D모델을 설계하였다. 해석 결과 모델의 두께가 두꺼울수록 발생한 크랙의 길이가 길게 나타났고, 높은 하중이 발생하였다. 이와 같은 연구에서 얻어진 해석 결과를 통하여 알루미늄 폼 재질로 접합된 실제 복합재 구조물에 적용시켜 파괴거동을 분석하고 그 기계적인 특성을 파악할 수 있다.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.335-342
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• 2006

Metal aluminum, of which has a low standard reduction potential, participates in the electrochemical oxidation reaction and results in the structural change and accompanying property variation of aluminum and its oxide film. Aluminum was electrochemically etched in acid solution and the surface area was magnified by the formation of high density etch pits. Etched aluminum was covered with a compact and dense dielectric oxide film by anodization and applied to the capacitor electrode. Anodization of aluminum in acid solution at low temperature makes a nanoporous aluminum oxide layer which can be used for the fabrication template of nanostructural materials. Electrochemical characteristics of aluminum turn the metal aluminum into functional materials and it will bring the diverse applications of metal aluminum.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.6
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• pp.239-245
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• 2001

$Al/Al_2O_3$composites were prepared from the reaction of mullite preforms and amorphous silica in aluminum melt at $1100^{\circ}C$ for 5 hrs. The chemical reaction between mullite preform and aluminum melt has formed the interconnected microstructure. The metal content of $Al/Al_2O_3$composite was controlled with the variable of the apparent porosity according to the sintering temperature of mullite preforms; $1600^{\circ}C$,$ 1625^{\circ}C$, $1650^{\circ}C$ and $1700^{\circ}C$, the mechanical properties of $Al/Al_2O_3$composite were investigated upon the content of Al. The mullite preform sintered above $1600^{\circ}C$ showed the chemical reaction with the penetrated Al melt, but the mullite sintered at $1600^{\circ}C$ didnt react with aluminum melt owing to the non-wetting of Al melt/mullite preform. The influences of penetration direction on the mechanical properties of composites were considered with the two different models of the perpendicular pattern and the parallel pattern to the direction of Al melt penetration. With the increase of Al metal penetration content, the fracture strength of $Al/Al_2O_3$composite decreased and the fracture toughness of composite increased. The microstructure of $Al/Al_2O_3$composite was determined by the direction of metal penetration, but the fracture strength and fracture toughness of composite didnt show the dependence on metal penetration direction.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.646-648
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• 2012

본 연구에서 다루는 복합재료는 알루미늄 폼으로써 다공성 구조체로 고체 알루미늄 금속에 비하여 비중이 1/10 정도로 작고, 충격에너지 흡수가 우수하다. 본 연구에서는 다공성 심재를 갖는 복합재료 알루미늄 폼 코어의 충격실험을 실시하여 기계적 특성을 파악하였다. 시험편은 알루미늄 폼 코어를 갖는 복합재료로써 시험편에 50J의 저 충격에너지를 가하도록 하였다. 그 결과, 모든 실험에서 스트라이커가 상부면재 통과 시 최대하중이 나타났고, 이때의 최대하중 값은 약 5.5 KN으로 나타났다. 또한 최대 하중 발생 시간은 50J일 때 약 4.2 ms가 나왔다. 최대 하중이 발생한 후, 즉 상부 면재 통과 후에 실험에서는 약 10 mm정도를 더 뚫으면서 심재에 까지 손상을 주었지만 하부 면재에는 손상을 주지 못하였다. 이로써 스트라이커가 알루미늄 폼 코어 샌드위치 복합재료를 통과 할 때 상부면재 통과 시 최대 하중이 발생하고 심재를 지나며 서서히 감소되는 것을 볼 수 있었다.

• Composites Research
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• v.23 no.6
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• pp.14-18
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• 2010

Among the factors that threaten spacecraft, Micrometeoroid and Orbital Space Debris(MMOD) cause damage to spacecraft and impact velocity is about 8~70km/s. Nowadays, various Whipple Shield are studied and applied to protect spacecraft. As the materials used to Shielding System, aluminum is usually used but composite is also used increasingly. So this study compared characteristics of hypervelocity impact of Aluminum and composites through finite element analysis. The Projectile was a spherical shape using Aluminum 2017-T4, and aluminum plate was using Aluminum 6061-T6, CFRP plate was using T300/5208. Initial impact velocity of projectile was 1km/s. As a result, kinematic energy of projectile decreased to about 64J and about 63J for aluminum plate and CFRP plate, respectively after impact. Although both results is almost same about the absorption of impact energy, you can think the CFRP has good ballistic characteristic, because CFRP is lighter about 1.7 times compared with density of aluminum.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.18.1-18.1
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• 2009

금속 다공체는 자동차, 선박, 건축 등의 분야에서 구조물이나 충격흡수제 등으로 응용되고 있는데 이들은 일반 금속 구조물에 비해 가볍고 플라스틱에비해서는 강한 장점을 지닌다. 현재 사용되고 있는 대부분의 금속 다공체는 발포 주조공정으로 제조된 알루미늄으로서, 철계 합금에 비해 가벼운 장점을 갖지만 강도가 상당히 떨어지고 가격이 높은 단점을 가진다. 따라서 본 연구에서는 알루미늄 대신 철계 합금으로 다공체를 제조하고자 하였고 제조방법으로는 주조공정 대신 분말공정을선택하였다. 분말공정은 구형 스티로폼을 금속분말 슬러리로 코팅한 후 스티로폼을 제거하여 낱개의 금속중공체(Metallic Hollow Sphere)를 제조하고 이렇게 제조된 중공체를 뭉쳐 성형함으로써최종 형상의 다공체를 제조하는 방법이다. 이 방법으로 제조된 다공체는 주조공정으로 제조된 다공체보다높은 강도를 나타내며 낱개의 중공체는 성형공정을 거치지 않고 필터나 충진재 등의 새로운 용도로 활용될 수 있다.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.466-473
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• 2017

Recently, domestic railway related institutes are developing pantographs for high speed trains; to lighten the upper arm, this device has a composite structure of CFRP (Carbon Fiber Reinforced Plastic) and aluminum instead of conventional steel. In the case of KTX-Sancheon, the pantograph must have a large current capacity because this system is of power-car type, supplying all necessary power for the train through a single pantograph. If the thickness of the pipe is arbitrarily increased in order to increase the current carrying capacity, without analyzing the thermal characteristics of the aluminum pipe, the increase in the weight of the upper arm may cause degradation of the current collecting performance. Therefore, in this paper, using the thermal analysis technique, we analyze the temperature change characteristics of the aluminum pipe of the upper arm over time, while receiving power at the stationary state of the KTX-Sancheon; we also examine the adequacy of the minimum thickness of the aluminum pipe in accordance with the proposed pantograph flow capacity.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.986-995
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• 2008

This study introduces the testing results of the AL car body which is applied to LRT. The LRT car body is made of aluminum structure materials like a sandwich panel. The static load test was performed to evaluate the structural characteristic and stability of the AL car body. Considering the vertical, compressive, twisting load and 3-point supporting, Bend natural frequency Measurement, Twist natural frequency Measurement type as a testing terms, the structural stability of a car body was evaluated.

• Clean Technology
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• v.28 no.2
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• pp.154-162
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• 2022

Microstructured Al@Al₂O₃ and Al@Ni-Al LDH (LDH = layered double hydroxide) core-shell metal-ceramic composites are prepared by hydrothermal reactions of aluminum (Al) metal substrates. Controlled hydrothermal reactions of Al metal substrates induce the hydrothermal dissolution of Al ions at the Al-substrate/solution interface and reconstruction as porous metal-hydroxides on the Al substrate, thereby constructing unique metal-ceramic core-shell composite structures. The morphology, composition, and crystal structure of the core-shell composites are affected largely by the ions in the hydrothermal solution; therefore, the critical physicochemical and surface properties of these unique metal-ceramic core-shell microstructures can be modulated effectively by varying the solution composition. A Ni/Al@Al₂O₃ catalyst with highly dispersed catalytic Ni nanoparticles on an Al@Al₂O₃ core-shell substrate was prepared by a controlled reduction of an Al@Ni-Al LDH core-shell prepared by hydrothermal reactions of Al in nickel nitrate solution. The reduction of Al@Ni-Al LDH leads to the exolution of Ni ions from the LDH shell, thereby constructing the Ni nanoparticles dispersed on the Al@Al₂O₃. The catalytic properties of the Ni/Al@Al₂O₃ catalyst were investigated for CO₂ methanation reactions. The Ni/Al@Al₂O₃ catalyst exhibited 2 times greater CO₂ conversion than a Ni/Al₂O₃ catalyst prepared by conventional incipient wetness impregnation and showed high structural stability. These results demonstrate the high effectiveness of the design and synthesis methods for the metal-ceramic composite catalysts derived by hydrothermal reactions of Al metal substrates.