Journal of Powder Materials

Jae-Kil Han

3 Articles

A Study of Mechanical Properties and Microstructure of ZrO₂-Ag Depending on the Composite Route: In-Chul Yeo, Jae-Kil Han, In-Cheol Kang; J Korean Powder Metall Inst. 2012;19(6):416-423.; DOI: https://doi.org/10.4150/KPMI.2012.19.6.416

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Abstract PDF: This paper introduces an effect of a preparing ZrO_2-Ag composite on its mechanical properties and microstructure. In present study, ZrO_2-Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into ZrO_2 powder during wetting dispersive milling in D.I. water. Each sample was sintered at 1450°C for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated ZrO_2 showed homogeneously dispersed Ag in ZrO_2 in where pore defect did not appear. However, ZrO_2-nano Ag and ZrO_2-micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.

Microstructure and Synthesis of Ag Spot-coated Cu Nanopowders by Hydrothermal-attachment Method using Ag Colloid: Hyeong-Chul Kim, Jae-Kil Han; J Korean Powder Metall Inst. 2011;18(6):546-551.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.546

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Ag spot-coated Cu nanopowders were synthesized by a hydrothermal-attachment method (HA) using oleic acid capped Ag hydrosol. Cu nano powders were synthesized by pulsed wire exploding method using 0.4 mm in diameter of Cu wire (purity 99.9%). Synthesized Cu nano powders are seen with comparatively spherical shape having range in 50 nm to 150 nm in diameter. The oleic acid capped Ag hydrosol was synthesized by the precipitation-redispersion method. Oleic acid capped Ag nano particles showed the narrow size distribution and their particle size were less than 20 nm in diameter. In the case of nano Ag-spot coated Cu powders, nanosized Ag particles were adhered in the copper surface by HAA method. The components of C, O and Ag were distributed on the surface of copper powder.

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Synthesis and visible light photocatalytic activity of Ag spot-coated TiO2–60 wt% SrO composite powders
Hyeong-Chul Kim, Jae-Kil Han
Research on Chemical Intermediates.2014; 40(7): 2431. CrossRef
Microstructure and Synthesis of Nano Palladium Spot Coated Activated Carbon Powders by Hydrothermal Attachment Method
Hyeong Chul Kim, Jae Kil Han
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 424. CrossRef

The Relation Between a Visible-light Photocatalytic Activity of TiO_2-xN_x and NH₃ Amount/the Period of Grinding Time: In-Cheol Kang, Jun-Bin Ko, Jae-Kil Han, Kwang-Hee Kim, Sung-Chang Choi; J Korean Powder Metall Inst. 2009;16(3):196-202.; DOI: https://doi.org/10.4150/KPMI.2009.16.3.196

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Abstract PDF: A visible-light photoactive TiO_2-xN_x photocatalyst was synthesized successfully by means of cogrinding of anatase-TiO_2(a-TiO_2) in NH_3 ambient, followed by heat-treatment at 200°C in air environment. In general, it is well known that the grinding-operation induces phase transformation of a-TiO_2 to rutile TiO_2. This study investigates the influence of the amount of NH_3 gas on the phase transformation rate of a-TiO_2 and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a-TiO_2 to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than NH_3 amount injected, which means that the doping amount of nitrogen into TiO_2 more effective to mechanical energy than NH_3 amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.

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