• 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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• 1999.10a
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• pp.13-13
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• 1999

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2002.04b
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• pp.14-15
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• 2002

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2005.04a
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• pp.26-27
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• 2005

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.10b
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• pp.31-31
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• 1994

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.04c
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• pp.26-26
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• 1994

• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.210-214
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• 2007

Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy via compaction and sintering. In the study, densification behavior of nano Cu powders during pressureless sintering was investigated using an in-situ optical dilatometer technique. The initial heating and steady temperature stages during the sintering of nano Cu powder compacts were observed. At the initial heating stage, the powder compact has many porosities and full densification needs high temperature and/or high pressure sintering. In the experimental analysis, changes in geometry and density were measured and discussed for optimal consolidation and densification by the in-situ optical dilatometer.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.631-634
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• 2003

To fabricate W-Cu nanocomposite powder, $WO_3$-CuO powder mixture was high-energetically ball-milled and subsequently hydrogen-reduced. The effect of ball-milling on the hydrogen-reduction behavior of$ WO_3$-CuO was investigated with non-isothermal hygrometric analysis during hydrogen-reduction. Increasing the ball-milling time, the reduction peak temperatures of humidity curves were shifted to low temperature. It was considered that the reduction temperature should be decreased because the specific surface area of each oxide considerably increased with increasing the ball-milling time. In case of ball-milling for 0 h, $WO_3$and CuO were independently hydrogen-reduced and W particles were nucleated on the surface of Cu adjacent to W by CVT. However, in case of ball-milling for 50 h, the aggregates of about 200-300 nm were observed. W particles of size below 30-50 nm were homogeneously distributed with Cu in the aggregates.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.218-221
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• 2011

We modified the optical properties of the $CuInS_2$ nanocrystal (NC) by alloying. Nanocrystals (NCs) with alloyed cores were synthesized by refluxing the as-synthesized $CuInS_2$ NCs with a mixture of cadmium acetate, zinc acetate and palmitic acid. The shift in emission wavelength of the NCs after shell layer formation was minimized by alloying. The photoluminescence (PL) spectra showed significant reduction of emission intensity. A detailed study on the emission process of NCs implies that the formation of shell layers with small lattice mismatch minimized the mismatch strain generated from the shell layers in contrast to core alloyed NCs. In particular, time-resolved PL spectra of the NCs showed a significant increase in the lifetime of excited carriers by modifying the band alignment of the NCs by modifying the shell composition.

• Journal of Powder Materials
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• v.13 no.5 s.58
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• pp.351-359
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• 2006

Ni based($Ni_{57}Zr_{20}Ti_{18}Si_2Sn_3$) bulk metallic glass(BMG) powders were produced by a gas atomization process, and ductile Cu powders were mixed using a spray drying process. The Ni-based amorphous powder and Cu mixed Ni composite powders were compacted by a spark plasma sintering (SPS) processes into cylindrical shape. The relative density varied with the used SPS mold materials such as graphite, hardened steel and WC-Co hard metal. The relative density increased from 87% to 98% when the sintering temperature increased up to $460^{\circ}C$ in the WC-Co hard metal mold.