- The Effect of Composition on Hydrogen Reduction Behavior of Ball-milled WO3-CuO Nanocomposite Powders
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Sung-Soo Jung, Yun-Sung Kang, Jai-Sung Lee
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J Korean Powder Metall Inst. 2006;13(3):205-210.
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DOI: https://doi.org/10.4150/KPMI.2006.13.3.205
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- The effect of Cu content on hydrogen reduction behavior of ball-milled WO_3-CuO nanocomposite powders was investigated. Hydrogen reduction behavior and reduction percent(alpha) of nanopowders were characterized by thermogravimetry (TG) and hygrometry measurements. Activation energy for hydrogen reduction of WO_3 nanopowders with different Cu content was calculated at each heating rate and reduction percent(alpha). The activation energy for reduction of WO_3 obtained in this study existed in the ranging from 129 to 139 kJ/mol, which was in accordance with the activation energy for WO_3 powder reduction of conventional micron-sized.
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Citations
Citations to this article as recorded by  - Microstructural Feature of Full-densified W-Cu Nanocomposites Containing Low Cu Content
Jai-Sung Lee, Sung-Soo Jung, Joon-Phil Choi, Geon-Yong Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(2): 138. CrossRef - Consolidation of Iron Nanopowder by Nanopowder-Agglomerate Sintering at Elevated Temperature
Jai-Sung Lee, Joon-Chul Yun, Joon-Phil Choi, Geon-Yong Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(1): 1. CrossRef
- Brazing Adhesion Properties of Ag Coated W-Ag Electric Contact on the Cu Substrate
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Hyun-Goo Kang, Yun-Sung Kang, Jai-Sung Lee
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J Korean Powder Metall Inst. 2006;13(1):18-24.
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DOI: https://doi.org/10.4150/KPMI.2006.13.1.018
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Abstract
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- The brazing adhesion properties of Ag coated W-Ag electric contact on the Cu substrate have been investigated in therms of microstructure, phase equilibrium and adhesion strength. Precoating of Ag layer (3µm in thickness) on the W-40%Ag contact material was done by electro-plating method. Subsequently the brazing treatment was conducted by inserting BCuP-5 filler metal (Ag-Cu-P alloy) layer between Ag coated W-Ag and Cu substrate and annealing at 710°C in H_2 atmosphere. The optimum brazing temperature of 710°C was semi-empirically calculated on the basis of the Cu atomic diffusion profile in Ag layer of commercial electric contact produced by the same brazing process. As a mechanical test of the electric contact after brazing treatment the adhesion strength between the electric contact and Cu substrate was measured using Instron. The microstructure and phase equilibrium study revealed that the sound interlayer structure was formed by relatively low brazing treatment at 710°C. Thin Ag electro-plated layer precoated on the electric contact (3µm in thickness) is thought to be enough for high adhesion strength arid sound microstructure in interface layer.
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