• Proceedings of the KSME Conference
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• 2007.05a
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• pp.37-42
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• 2007

We present a powder injection molding technique of fabricating cemented tungsten carbide(WC) balls for milling and dispersing nano-powder in this paper. The conventional powder metallurgy approach is investigated to reveal its drawbacks of density non-homogeneity. New procedures of powder injection molding for the homogeneous high-precision WC balls, involving the binding process, powder injection molding process and sintering process, are presented in detail. Each process is investigated empirically and numerically to obtain its engineering information, which can used for process optimization.

• Journal of Powder Materials
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• v.15 no.3
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• pp.173-181
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• 2008

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.04a
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• pp.59-60
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• 2004

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.95-96
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• 2003

Titanium carbide nano-tube and fibers were synthesized by self-propagating high temperature synthesis (SHS) method. The average diameters of the nano-tubes and nano-fibers are about 100 and 20 nm in diameter, respectively. the non-stoichiometric numbers of the titanium carbide determined by neutron diffractometry were 0.87 and 0.94.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.371-374
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• 2007

A method for metal nano powder imprinting is proposed as a patterning process for conductive tracks that is inexpensive and scalable down to the nanoscale. Conductive tracks with line widths of $0.5{\sim}20{\mu}m$ were fabricated using this method. The processing conditions were optimized to avoid various types of defects, and to increase the degree of sintering and electric conductivity of the imprinted conductive tracks. The mean electric resistivity of the conductive tracks imprinted under optimum conditions was $8.95{\mu}{\Omega}{\cdot}cm$, which is in the range required for practical applications.

• Journal of Powder Materials
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• v.11 no.1
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• pp.22-27
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• 2004

The Indium Tin Oxide(ITO) nano powders were prepared by spray drying and heat treatment process. The liquid solution dissolved Indium and Tin salts was first spray dried to prepare chemically homogeneous recursor powders at the optimum spray drying conditions. Subsequently, the precursor powders were subjected to eat treatment process. The nano size ITO powders was synthesized from the previous precursor powders and the npuities also were decreased with increasing heat treatment temperature. Furthermore, the lattice parameter of TO nano powders was increased by doping Tin into Indium with increasing heat treatment temperature. The par icle size of the resultant ITO powders was about 20∼50nm and chemical composition was composed of In:Sn =86:10 wt.％ at 80$0^{\circ}C$.

• 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 Powder Materials
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• v.14 no.2 s.61
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• pp.116-122
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• 2007

It is well known that thermal plasma process has lots of advantages such as high temperature and good quality for synthesis of nano particles. In this research, we attempt the synthesis of nano unitary and composite powder (Ag, Mg-Al, Zr-V-Fe) using transferred thermal plasma. Nano particles of metal alloy, ranging from 20 nm to 150 nm, have been synthesized by this process.

• Journal of Powder Materials
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• v.14 no.6
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• pp.391-398
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• 2007

The surface roughness of Al, Ag and Ni nano-powders which were prepared by pulsed wire evaporation method was quantified based upon the fractal theory. The surface fractal dimensions of metal nano-powders were determined from the linear relationship between In $V/V_{mono}$ and Inln ($P^o/P$) using multi-layer gas adsorption theory. Moreover, the fractal surface image was realized by computer simulation. The relationship between preparation condition and surface characteristics of metal nano-powders was discussed in detail.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.955-956
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• 2006

Fe-doped $TiO_2$ nanopowders were prepared by mechanical alloying (MA) varying Fe contents up to 8.0 wt.%. The UV-vis absorption showed that the UV absorption for the Fe-doped powder shifted to a longer wavelength (red shift). The absorption threshold depends on the concentration of nano-size Fe dopant. As the Fe concentration increased up to 4 wt.%, the UV-vis absorption and the magnetization were increased. The benefical effect of Fe doping for photocatalysis and ferromagnetism had the critical dopant concentration of 4 wt.%. Based on the UV absorption and magnetization, the dopant level is localized to the valence band of $TiO_2$.