• Journal of Powder Materials
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• v.9 no.2
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• pp.124-132
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• 2002

Nano Cu powders, synthesized by Pulsed Wire Evaporation (PWE) method, have been compacted by Magnetic Pulsed Cojpaction(MPC) method. The microstructure and mechanical properties were analyzed. The optimal condition for proper mechanical properties with nanostructure was found. Both pure nano Cu powders and passivated nano Cu powders were compacted, and the effect of passivated layer on the mechanical properties was investigated. The compacts by MPC, which had ultra-fine and uniform nanostructure, showed higher density of 95% of theoretical density than that of static compaction. The pur and passivated Cu compacted at $300^{\circ}C$ exhibited maximum hardnesses of 248 and 260 Hv, respectively. The wear resistance of those compacts corresponded to the hardness.

• Journal of Magnetics
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• v.13 no.2
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• pp.70-75
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• 2008

In this study, a MOKE (Magneto-optical Kerr effect) measurement method for magnetic nanostructures is proposed. Theoretically, the MOKE signal enhancement can be predicted and confirmed when an anti-reflection coated substrate is used. Since MOKE is a ratio of reflectivity and the difference between the reflectivities for two magnetic states, when the reflectivity of the substrate part is reduced by employing an anti-reflection coated substrate, MOKE signal enhancement can be achieved. The enhancement is confirmed by simple numerical MOKE calculations. When the reflectivity of an anti-reflection coated substrate is 0.7%, the calculated MOKE signal is about 79% of its bulk values for the 100-nm wide Fe nanowire with a 1500-nm radius laser beam. It was found that, for various numerical calculations, a larger MOKE signal is obtained relative to a smaller substrate reflectivity.

• Proceedings of the Korean Magnestics Society Conference
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• 2001.10a
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• pp.30-31
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• 2001

• Proceedings of the Korean Magnestics Society Conference
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• 2017.05a
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• pp.101-102
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• 2017

• Journal of Powder Materials
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• v.15 no.1
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• pp.37-45
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• 2008

This article presents the challenges toward the successful consolidation of $Al_2O_3$ nanopowder using magnetic pulsed compaction (MPC). In this research the ultrafine-structured $Al_2O_3$ bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were investigated. The obtained density of $Al_2O_3$ bulk prepared by the combined processes was increased with increasing MPC pressure from 0.5 to 1.25 GPa. Relatively higher hardness and fracture toughness in the MPCed specimen at 1.25 GPa were attributed to the retention of the nanostructure in the consolidated bulk without cracks. The higher fracture toughness could be attributed to the crack deflection by homogeneous distribution and the retention of nanostructure, regardless of the presence of porosities. In addition, the as consolidated $Al_2O_3$ bulk using magnetic pulsed compaction showed enhanced breakdown voltage.

• Steel and Composite Structures
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• v.37 no.2
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• pp.229-251
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• 2020

In this paper, dynamic buckling of a smart sandwich nanotube is studied. The nanostructure is composed of a carbon-nanotube with inner and outer surfaces coated with ZnO piezoelectric layers, which play the role of sensor and actuator. Nanotube is under magnetic field and ZnO layers are under electric field. The nanostructure is located in a viscoelastic environment, which is assumed to obey Visco-Pasternak model. Non-local piezo-elasticity theory is used to consider the small-scale effect, and Kelvin model is used to describe the structural damping effects. Surface stresses are taken into account based on Gurtin-Murdoch theory. Hamilton principle in conjunction with zigzag shear-deformation theory is used to obtain the governing equations. The governing equations are then solved using the differential quadrature method, to determine dynamic stability region of the nanostructure. To validate the analysis, the results for simpler case studies are compared with others reported in the literature. Then, the effect of various parameters such as small-scale, surface stresses, Visco-Pasternak environment and electric and magnetic fields on the dynamic stability region is investigated. The results show that considering the surface stresses leads to an increase in the excitation frequency and the dynamic stability region happens at higher frequencies.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.290-290
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• 2008

• Journal of Magnetics
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• v.14 no.1
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• pp.31-35
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• 2009

Herein, the Magneto-Optical Kerr Effect (MOKE) signal enhancement in nanostructures in investigated. It is well known that the MOKE signals of ferromagnetic thin films are enhanced with an additional dielectric layer due to multiple reflections. The MOKE signal is modulated with the additional dielectric layer thickness and is at a maximum when reflectivity is at a minimum. This is not always true in the nanostructures due to the contribution from the non-magnetic substrate portion, especially when substrate reflectivity is minimized and the dependence of the additional dielectric layer thickness for the nanostructure is changed in the case of the continuous thin film. We showed that the MOKE signal for nanostructures could be enhanced with a properly designed, dielectric layer in addition to the anti-reflection coated substrates.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.207-212
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• 2009

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.528-530
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• 2008

The effect of consolidation temperature on the microstructure, density and mechanical properties (especially, wear property) of $Al_{92.5}-Fe_{2.5}-Cr_{2.5}-Ti_{2.5}$ alloy fabricated by gas atomization and magnetic pulsed compaction was investigated. All consolidated alloys consisted of homogeneously distributed fine-grained fcc-Al matrix and intermetallic compounds. Relative higher mechanical properties in the MPCed specimen were attributed to the retention of the nanostructure in consolidated bulk without cracks. The as consolidated bulk by magnetic pulsed compaction showed the enhanced wear properties than that of a general consolidation process. In addition, the wear mechanism and fracture mode of MPCed bulk was discussed.