• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.04a
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• pp.25-25
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• 2003

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.89-90
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• 2006

The CNTs are of great interest because of their unique complete properties of matter, especially, the large thermal conductivity (Thermal conductivity of CNTs ~ >2000W /mK vs. Thermal conductivity of Aluminum ~ >204W/mK). However, owing to the strong agglomeration cause by the vander wall's force, the CNTs are limited to applicate. In this study. we suggest a new method for CNTs dispersion. which are developed by the mechanical and chemical method. and then Cu was coated. This new process produces CNTs/Cu nanocomposite powders. The CNTs are homogeneously located within the Cu powders by chemical reaction. And the thermal properties of the CNTs/Cu nanocomposite were investigated.

• Journal of Powder Materials
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• v.13 no.3 s.56
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• pp.205-210
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• 2006

The effect of Cu content on hydrogen reduction behavior of ball-milled $WO_3$-CuO nanocomposite powders was investigated. Hydrogen reduction behavior and reduction percent(${\alpha}$) of nanopowders were characterized by thermogravimetry (TG) and hygrometry measurements. Activation energy for hydrogen reduction of $WO_3$ nanopowders with different Cu content was calculated at each heating rate and reduction percent(${\alpha}$). The activation energy for reduction of $WO_3$ obtained in this study existed in the ranging from 129 to 139 kJ/mol, which was in accordance with the activation energy for $WO_3$ powder reduction of conventional micron-sized.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1378-1381
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• 2006

The CNTs are the most extensively studied material which are characterized by the complete property of matter, structure, and the large thermal conductivity (Thermal conductivity of $CNTs\;{\sim}>2000W/mK$ vs. Thermal conductivity of Aluminum ${\sim}\;>204W/mK$). Thus, they are successfully applied to the various fields. However, due to the strong agglomeration caused by the van der waal's force, their applications are limited. In the present study, a new method for CNTs dispersion was developed by using the mechanical dispersion, acid treatment, and then Cu was coated. This process produces CNTs/Cu nanocomposite powders, whereby the CNTs are homogeneously located within the Cu powders. The thermal properties of the CNTs/Cu nanocomposite were investigated.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.25-25
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• 2004

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.126-126
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• 2003

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.11a
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• pp.36-36
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• 2002

최근 한국기계연구원에서 개발된 Mechanochemical process (MCP)는 Spray conversion 법에 의하여 나노크기의 W/Cu 복합 분말을 제조하는 방법으로서, 현재 (주)나노테크에서 산업화를 위한 시험/개발이 진행 중이다. 이 방법에 의하여 W /1 0 ~ 40wt. %Cu 조성의 초미렵 W/Cu 복합 분말의 양산화가 가능하게 됨으로써, 나노복합분말을 사용한 초미립 W/Cu 합금의 소결 제조 연구 역시 나 노태크에서 분말사업화와 동시에 수행되고 있다. 현재 Spray conversion 법으로 제조되고 있는 W/Cu 나노복합분말 및 그 소결체는 Cu의 조성범 위에 따라 민수용 및 군수용 제품으로의 적용이 시도되고 있으며, 각기 특성향상을 목표로 각 적용 분야에서 요구되는 제반 성능에 대한 검토가 이루어지고 있다. 특히 군수용의 목적으로 사용될 경우, 정적 및 동적부하상태에서 재료의 균일한 변형이 가장 중요한 특성이다. 현 개발품의 경우, 일반 W 빛 Cu 원료에 비하여 상대적으로 높은 순도의 원료를 사용하였기 때문에 분말 및 소재상태 에서의 순도가 높아서, 연성을 저하시키는 것으로 알려진 기지상내 합금원소 또는 interface 게재물 이 존재할 가능성이 매우 낮다. 또한 초미립 W 입자들과 Cu 상의 혼합도가 극대화된 상태이기 때문에 상대적으로 저옹에서도 완전치밀화된 미세조직을 얻을 수 있는데, 이는 분말상태의 균일한 미세구조를 유지할 수 있으며, 동시에 W 업자간의 과도한 neck 형성을 방지함으로써 기계적 변형시 재료의 연성 향상이 기대된다. 이러한 W/Cu 나노복합분말 소결체의 특성은 균일한 밀도분포와 동시에 과도한 동적 부하상태에서 균일한 변형이 보장되어야만 하는 특정 군수용 목적에 잘 부합하는 것으로 판단된다. 본 고에서는 상기한 W/Cu 나노복함분말을 사용하여 균일한 미세구조를 가지는 완전치밀화된 소결재를 제조하는 과정과 제조된 소결재를 향후 군수용 제품에 척용시키기 위하여 진행된 단조특성에 대한 연구결과틀을 재료의 미세구조척 관점에서 논의하였다.

• Journal of Environmental Science International
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• v.29 no.12
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• pp.1213-1222
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• 2020

In the current study, a Cu2O/TiO2 photoinduced nanocomposite materials prepared by ultrasonification method was evaluated the photocatalytic oxidation efficiency of volatile organic compounds (BTEX) under visible-light irradiation. The results of XRD confirmed the successful preparation of photoinduced nanocomposite materials. However, diffraction peaks belonging to TiO2 were not confirmed for the Cu2O/TiO2. The possible reason for the absence of Cu2O peak is their low content and small particle size. The result of uv-vis spectra exhibited that the fabricated Cu2O/TiO2 can be activated under visible light irradiation. The FE-SEM/EDS and TEM showed the formation of synthesized nanocomposites and componential analysis in the undoped TiO2 and Cu2O/TiO2. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with Cu2O/TiO2 were higher than undoped TiO2. According to light sources, the average oxidation efficiencies for BTEX by Cu2OT-0.5 were exhibited in the orer of 8 W day light > violet LEDs > white LEDs. However, the photocatalytic oxidation efficiencies normalized to supplied electric power were calculated to be in the following order of violet LEDs > white LEDs > 8 W day light, indicating that the LEDs could be a much more energy efficient light source for the photo-oxidation of gaseous BTEX using Cu2O/TiO2.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.169-173
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• 2003

W-Cu composite powders can be prepared by mechanochemical process, where the $WO_3$-CuO composite powders were mechanically synthesized from the elemental oxide powders and subsequently reduced to W-Cu composite powders. In the present work, reduction behavior of$ WO_3$-CuO composite powders that were synthesized at different milling time was examined in terms of hygrometric analysis. In case of $WO_3$-CuO ball-milled for 20 h, the reaction temperature of CuO\longrightarrowCu became lower than in case of 1 h. Also, the reaction of $WO_3$\longrightarrow$WO_{2.9-2.72}$ and $WO_{2.9-2.72}$ \longrightarrow$WO_2$were shifted to lower temperatures and the peaks were changed to much sharper shape. While the reaction of $WO_2$\longrightarrowW in case of ball-milling for 20 h started at lower temperature, the peak temperature was the same as in 1 h ball-milling. The reduced W particle size was somewhat finer fer 20 h ball-milling. It was considered that the refinement of oxide particles caused by ball-milling process leads to such a change in the reduction behavior.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4671-4677
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• 2023

For the first time Pb, Ni, and Cu nanocomposites were synthesized by versatile solution combustion synthesis using Aloevera extract as a reducing agent, to study the potential applications in X-ray/gamma, neutron, and Bremsstrahlung shielding. The synthesized Lead-Nickel-Copper (LNC) nanocomposites were characterized by PXRD, SEM, UV-VIS, and FTIR for the confirmation of successful synthesis. PXRD analysis confirmed the formation of multiphase LNC NCs and the Scherrer equation and the W-H plot gave the average crystal sizes of 19 nm and 17 nm. Surface morphology using SEM and EDX confirmed the presence of LNC NCs. Strong absorption peaks were analyzed by UV visible spectroscopy and the direct energy gap is found to be 3.083 eV. Functional groups present in the LNC NCs were analyzed by FTIR spectroscopy. X-ray/gamma radiation shielding properties were measured using NaI(Tl) detector coupled with MCA. It is found to be very close to Pb. Neutron shielding parameters were compared with traditional shielding materials and found LNC NCs are better than lead and concrete. Secondary radiation shielding known as Bremsstrahlung shielding characteristics also studied and found that LNC NCs are best in secondary radiation shielding. Hence LNC NCs find shielding applications in ionizing radiation such as X-ray/gamma and neutron radiation.