- Characterization of Classification of Synthesized Ni Nanopowders by Pulsed Wire Evaporation Method
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Joong-Hark Park, Geon-Hong Kim, Dong-Jin Lee, Soon-Jik Hong
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J Korean Powder Metall Inst. 2017;24(5):389-394. Published online October 1, 2017
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DOI: https://doi.org/10.4150/KPMI.2017.24.5.389
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Abstract
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Ni wires with a diameter and length of 0.4 and 100 mm, respectively, and a purity of 99.9% are electrically exploded at 25 cycles per minute. The Ni nanopowders are successfully synthesized by a pulsed wire evaporation (PWE) method, in which Ar gas is used as the ambient gas. The characterization of the nanopowders is carried out using X-ray diffraction (XRD) and a high-resolution transmission electronmicroscope (HRTEM). The Ni nanopowders are classified for a multilayer ceramic condenser (MLCC) application using a type two Air-Centrifugal classifier (model: CNI, MP-250). The characterization of the classified Ni nanopowders are carried out using a scanning electron microscope (SEM) and particle size analysis (PSA) to observe the distribution and minimum classification point (minimum cutting point) of the nanopowders.
- The Effects of MoS2 Addition on the Mechanical Properties of Fe-Cr-Mn-C-V P/M Alloy
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Geon-Hong Kim, Hyun Seok Yang, Man-Sik Kong
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J Korean Powder Metall Inst. 2014;21(4):294-300. Published online August 1, 2014
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DOI: https://doi.org/10.4150/KPMI.2014.21.4.294
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Abstract
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The connecting rod is one of the most important parts in automotive engines, transforming the reciprocal motion of a piston generated by internal combustion into the rotational motion of a crankshaft. Recent advances in high performance automobile engines demand corresponding technological breakthroughs in the materials for engine parts. In the present research, the powder metallurgy (P/M) process was used to replace conventional quenching and/or tempering processes for mass production and ultimately for more cost-efficient manufacturing of high strength connecting rods. The development of P/M alloy powder was undertaken not only to achieve the improvement in mechanical properties, but also to enhance the machinability of the P/M processed connecting rods. Specifically MoS2 powders were added as lubricants to non-normalizing Fe-Cr-Mn-V-C alloy powder to improve the post-sintering machinability. The effects of MoS2 addition on the microstructure, mechanical properties, and machining characteristics were investigated.
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