http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Thuyet-Nguyen, Minh,Kim, Jin-Chun The Korean Powder Metallurgy Institute 2020 한국분말재료학회지 (KPMI) Vol.27 No.1
In this work, the electrical explosion of wire in liquid and subsequent spark plasma sintering (SPS) was introduced for the fabrication of Ni-graphite nanocomposites. The fabricated composite exhibited good enhancements in mechanical properties, such as yield strength and hardness, but reduced the ductility in comparison with that of nickel. The as-synthesized Ni-graphite (5 vol.% graphite) nanocomposite exhibited a compressive yield strength of 275 MPa (about 1.6 times of SPS-processed monolithic nickel ~170 MPa) and elongation to failure ~22%. The hardness of Ni-graphite composite had a value of 135.46 HV, which is about 1.3 times higher than that of pure SPS-processed Ni (105.675 HV). In terms of processing, this work demonstrated that this processing route is a novel, simple, and low-cost method for the synthesis of nickel-graphite composites.
Minh-Thuyet Nguyen,Hong-Hai Nguyen,김원주,김호윤,김진천 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.2
Nanomaterials have attracted great attention from chemists, physicists and materials scientists because oftheir application benefits and special properties. Thermoplastics have been used in many applications suchas molding of non-electrical components, conducting, magnetic field and 3D printing. Nanocomposites areknown as a material which blends the best properties of components, a high performance material exhibitsunusual property combinations and unique design possibilities. In this research, we focused to investigate andreport primary results in the synthesis of magnetic nanocomposites based on acrylonitrile butadiene styrene(ABS), which are useful and important thermoplastics. Nickel nanopowder was prepared by electrical explosionof wire in a liquid were used as magnetic component. The composites were prepared by following steps, firstthe obtained Ni nanopowders were incorporated into the ABS matrix via a solution blending method (drop-casting),and then the solvent was evaporated. The characterizations of obtaining composites were analyzed byfield emission scanning electron microscopy, X-Ray Diffraction analysis and vibrating sample magnetometer.
Minh, Thuyet-Nguyen,Hong, Hai-Nguyen,Kim, Won Joo,Kim, Ho Yoon,Kim, Jin-Chun The Korean Powder Metallurgy Institute 2016 한국분말재료학회지 (KPMI) Vol.23 No.3
In this study, bulk nickel-carbon nanotube (CNT) nanocomposites are synthesized by a novel method which includes a combination of ultrasonication, electrical explosion of wire in liquid and spark plasma sintering. The mechanical characteristics of the bulk Ni-CNT composites synthesized with CNT contents of 0.7, 1, 3 and 5 wt.% are investigated. X-ray diffraction, optical microscopy and field emission scanning electron microscopy techniques are used to observe the different phases, morphologies and structures of the composite powders as well as the sintered samples. The obtained results reveal that the as-synthesized composite exhibits substantial enhancement in the microhardness and values more than 140 HV are observed. However an empirical reinforcement limit of 3 wt.% is determined for the CNT content, beyond which, there is no significant improvement in the mechanical properties.
Some Characterizations of Modules via Essentially Small Submodules
Le, Van Thuyet,Phan, Hong Tin Department of Mathematics 2016 Kyungpook mathematical journal Vol.56 No.4
In this paper, the structure of e-local modules and classes of modules via essentially small are investigated. We show that the following conditions are equivalent for a module M: (1) M is e-local; (2) $Rad_e(M)$ is a maximal submodule of M and every proper essential submodule of M is contained in a maximal submodule; (3) M has a unique essential maximal submodule and every proper essential submodule of M is contained in a maximal submodule.
Selective Laser Sintering of Co-Cr Alloy Powders and Sintered Products Properties
이동완,Thuyet-Nguyen Minh,김진천 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.1
Metal-additive manufacturing techniques, such as selective laser sintering (SLS), are increasingly utilized for new biomaterials, such as cobalt-chrome (Co-Cr). In this study, Co-Cr gas-atomized powders are used as charge materials for the SLS process. The aim is to understand the consolidation of Co-Cr alloy powder and characterization of samples sintered using SLS under various conditions. The results clearly suggest that besides the matrix phase, the second phase, which is attributed to pores and oxidation particles, is observed in the sintered specimens. The as-built samples exhibit completely different microstructural features compared with the casting or wrought products reported in the literature. The microstructure reveals melt pools, which represent the characteristics of the scanning direction, in particular, or of the SLS conditions, in general. It also exposes extremely fine grain sizes inside the melt pools, resulting in an enhancement in the hardness of the as-built products. Thus, the hardness values of the samples prepared by SLS under all parameter conditions used in this study are evidently higher than those of the casting products.
Phuc, Chu Dac,Thuyet, Nguyen Minh,Kim, Jin-Chun The Korean Powder MetallurgyMaterials Institute 2020 한국분말재료학회지 (KPMI) Vol.27 No.6
Iron and copper are practically immiscible in the equilibrium state, even though their atomic radii are similar. As non-equilibrium solid solutions, the metastable Fe-Cu alloys can be synthesized using special methods, such as rapid quenching, vapor deposition, sputtering, ion-beam mixing, and mechanical alloying. The complexity of these methods (multiple steps, low productivity, high cost, and non-eco-friendliness) is a hinderance for their industrial applications. Electrical explosion of wire (EEW) is a well-known and effective method for the synthesis of metallic and alloy nanoparticles, and fabrication using the EEW is a simple and economic process. Therefore, it can be potentially employed to circumvent this problem. In this work, we propose the synthesis of Fe-Cu nanoparticles using EEW in a suitable solution. The powder shape, size distribution, and alloying state are analyzed and discussed according to the conditions of the EEW.
Hong-Hai Nguyen,Minh-Thuyet Nguyen,김원주,김진천 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.1
Nanocrystalline β1-Cu3Al and β2-NiAl intermetallic compounds were in-situ reinforced in the aluminum matrix with the atomic composition of Al67Cu20Ni13 by the mechanical alloying of elemental powders. Both β1-Cu3Al, β2-NiAl phases that can be only co-synthesized in Cu base alloys have been obtained after 15h milling in this study. The phase evolution during milling process was investigated by X-ray diffraction. The β1-Cu3Al, β2-NiAl phases were metastable with further milling time up to 40 h. Specially, unreacted Al matrix has been totally transformed to amorphous state in the final powder. A remarkable crystalline size of 6.5 nm was reached after 15 h milling time. Thermal stability of the milled powder was also studied by differential thermal analysis. It is shown that β1-Cu3Al, β2-NiAl phases were stable up to higher than 550 °C. Moreover, the inter-diffusion between Al matrix and Cu3Al within the temperature range of 620-740 °C led to the formation of superstructure ζ1-Al3Cu4 phase.
Spark Plasma Sintering of Fe-Ni-Cu-Mo-C Low Alloy Steel Powder
Nguyen, Hong-Hai,Nguyen, Minh-Thuyet,Kim, Won Joo,Kim, Ho Yoon,Park, Sung Gye,Kim, Jin-Chun The Korean Powder Metallurgy Institute 2016 한국분말재료학회지 (KPMI) Vol.23 No.3
In this study, Fe-Cu-Ni-Mo-C low alloy steel powder is consolidated by spark plasma sintering (SPS) process. The internal structure and the surface fracture behavior are studied using field-emission scanning electron microscopy and optical microscopy techniques. The bulk samples are polished and etched in order to observe the internal structure. The sample sintered at $900^{\circ}C$ with holding time of 10 minutes achieves nearly full density of 98.9% while the density of the as-received conventionally sintered product is 90.3%. The fracture microstructures indicate that the sample prepared at $900^{\circ}C$ by the SPS process is hard to break out because of the presence of both grain boundaries and internal particle fractures. Moreover, the lamellar pearlite structure is also observed in this sample. The samples sintered at 1000 and $1100^{\circ}C$ exhibit a large number of tiny particles and pores due to the melting of Cu and aggregation of the alloy elements during the SPS process. The highest hardness value of 296.52 HV is observed for the sample sintered at $900^{\circ}C$ with holding time of 10 minutes.