The mechanochemical milling of Mg and Mg_2Ni alloys were carried out to examine the enhancement of hydrogen storage properties of Mg alloys. The hydroge characteristics of the ball-milled products were evaluated with a Sievert-type apparatus and electrochemical test. Various intermediate compounds were obtained by chemical reactions induced during the ball milling of Mg of Mg_2Ni alloys with C, Ni, Ni_2Cl and Ca_2Cl. The system of Mg_2Ni with 10 wt% C improved markedly the kinetics of hydrogen absorption, while the hydrogen capacities were practically unchanged. The hydrogen storage alloys such as Mg-Ca can be successfully.
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Fabrication of Fe coated Mg Based Desulfurization Powder by Mechanical Alloying Process Joon-Woo Song, Otaduy Guillermo, Byong-Sun Chun, Soon-Jik Hong Journal of Korean Powder Metallurgy Institute.2012; 19(3): 226. CrossRef
Spherical fine powders of tungsten oxide powders were prepared by the emulsion evaporation method. The characteristics of the powders prepared were examined by means of TGA, X-ray diffraction, SEM and image analysis. The emulsions were prepared by fast mixing of aqueous phase containing tugsten and the organic phase which composed of kerosene, surfactant, and paraffin oil. Precursors were made by evaporating the emulsionin the kerosene bath at 160°C, and then calcined at 650°C in order to produce tungsten oxide powders. The average particle size of the tungsten oxide powders was 0.5mutextrmm and their shapes were spherical at the both case of w/o and o/w type emulsions. As the HLB value of the surfactant increased and the concentration of tungsten ions decreased the mean particle siqe of tungsten oxide powders decreased whereas agglomerationsize increased. The optimum concentration of Span 80 was 8 percent by volume, and the optimum stirring speed in the emulsion formation was 5000 rpm in order to obtain fine and well dispersed WO_3 powders.
In the present study, equiatomic porous TiNi shape-memory alloys have been successfully prepared by self-propagating high-temperature synthesis (SHS) using elemental titanium and nickel powders. The porous TiNi alloys thus obtained have an open porous structure with about 64 vol.% porosity, and the pore size is about 1.8 mm. The effect of preheating temperature on the microstructure have been investigated. It is found that the pore size increases with increasing preheating temperature. Moreover, the preheating temperature was shown to have a significant effect on the microstructrue of the SHS-synthesized porous TiNi shape memory alloys.
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Properties of Al/TiNi composite using porous TiNi fabricated by a self-propagating high temperature synthesis method In-Shup Ahn, Sung-Yeal Bae, You-Young Kim Metals and Materials International.2004; 10(1): 39. CrossRef
To investigate the fabrication possibility of a polymer particle dispersed metal matrix composite, polytetrafluorothylene (PTFE) particles were incorporated into the Al by the powder metallurgy process. The characteristics of a PTFE/Al composite were evaluated by measuring the density and hardness, and analysis of XRD, FT-Raman and microstructure. And wear properties of these composites were evaluated under the dry wear condition. It was possible to obtain the PTFE particles stably dispersed Al matrix composites by the hot press process at the sintering temperature of 500°C. The wear coefficient of a PTFE/Al compoite decreased with increasing of the volume fraction of PTFE. The wear weight of a PTFE/Al composite increased with increasing of the volume fractionof PTFE in the range of 0~10 vol.%PTFE, and showed maximum value at 10 vol.%PTFE, and then decreased at 20vol.%PTFE.
In order to obtain the nano size 10wt%Cu-TiO_2composite powders by mechanical alloying method for useful composite catalysis, the effects of mechanical alloying time on the formationof 10wt%Cu-TiO_2 composite powders were analyzed. The phase transformation behaviors were experimented as the heat treating temperature increased. Homogeneous 10wt% Cu-rutile type TiO_2composite powders were synthesized in 40 hours by mechanical alloying. After 60 hours mechanical alloying 50 nm size TiO_2powders were obtained. Both the phase of mechanically alloyed 10 wt% Cu-TiO_2 and pure TiO_2 powders were not transformed to anatase after annealing at the temperature range between 350 to 500 °C. The intermetallic compound of Cu_2Ti_4O was formed after 10 hours mechanical alloying, however it could be considered that this intemetallic phase dose not prevent the transformation of rutile TiO_2 to the anatase phase after heat treatment at the temperature between 350 and 550°C.
The characteristics of two commercial 2xxx series Al alloy powders, AMB2712 and 201AB, were evaluated and their compacting and sintering characteristics were discussed in tems of compacting pressure. The particle shapes of both two powder mixtures were irregular and their particle size distributions were broad. The compactibility of AMB2712 was superior to that of 201AB because of better fluidity. The sintered density was higher than the green density at low compacting pressure, however, it was lower than the green density when the samples were compacted at higher pressure due to the selling during sintering. The sintered density was alomost the same as the green density at the "homogeneous deformation" stage. It was observed that pores were created at the triple points due to the rapid diffusion of Cu in Al. Cu in Al.
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Liquid phase sintering of the commercial 2xxx series Al blended powder Kyung Ho Min, Shin Pil Kang, Baek-Hee Lee, Jeong-Keun Lee, Young Do Kim Journal of Alloys and Compounds.2006; 419(1-2): 290. CrossRef
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°C exhibited maximum hardnesses of 248 and 260 Hv, respectively. The wear resistance of those compacts corresponded to the hardness.
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Fabrication and Dynamic Consolidation Behaviors of Rapidly Solidified Mg Alloy Powders Hong-Jun Chae, Young-Do Kim, Taek-Soo Kim Journal of Korean Powder Metallurgy Institute.2011; 18(4): 340. CrossRef
Nanostructures and mechanical properties of copper compacts prepared by magnetic pulsed compaction method Geun Hee Lee, Chang Kyu Rhee, Min Ku Lee, Whung Whoe Kim, Victor V. Ivanov Materials Science and Engineering: A.2004; 375-377: 604. CrossRef
The effect of compaction temperature and pressure on the pores in nanostructured metal compacts prepared by magnetic pulsed compaction G. H. Lee, C. K. Rhee, K. H. Kim, Y. S. Han, W. W. Kim Metals and Materials International.2003; 9(4): 375. CrossRef