• Title/Summary/Keyword: Polymer coated metal powder

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Study for Applicability of Polymer and Polymer Coated Metal Materials within PBF System (PBF 시스템에서 고분자 및 금속 소재 적용성 연구)

  • Kim, Dong Soo;Bae, Sungwoo
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.9
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    • pp.765-771
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    • 2015
  • In an Additive Manufacturing (AM) system emplying the Powder Bed Fusion (PBF) system, polyamide-12 powder is currently recognized as the general material used. The Polyamide-12 powder's properties include an average particle size of 58 $58{\mu}m$, a density of 0.59 g/cm3, and melting point of $184^{\circ}C$, and can also be to used coat materials for metal powder. For this reason, the sintering process is similar to the polymer powder and polymer coated metal powder process, except during the post-process. The polyamide-12 powder has some disadvantages such as its high cost and the fact that it can only be used for the provided equipment from the maker. Therefore, this study aims to perform the applicability of new material, polymer and polymer coated metal, to the PBF system.

Microwave Absorbance of Polymer Composites Containing SiC Fibers Coated with Ni-Fe Thin Films

  • Liu, Tian;Kim, Sung-Soo;Choi, Woo-cheal;Yoon, Byungil
    • Journal of Powder Materials
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    • v.25 no.5
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    • pp.375-378
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    • 2018
  • Conductive and dielectric SiC are fabricated using electroless plating of Ni-Fe films on SiC chopped fibers to obtain lightweight and high-strength microwave absorbers. The electroless plating of Ni-Fe films is achieved using a two-step process of surface sensitizing and metal plating. The complex permeability and permittivity are measured for the composite specimens with the metalized SiC chopped fibers dispersed in a silicone rubber matrix. The original non-coated SiC fibers exhibit considerable dielectric losses. The complex permeability spectrum does not change significantly with the Ni-Fe coating. Moreover, dielectric constant is sensitively increased with Ni-Fe coating, owing to the increase of the space charge polarization. The improvements in absorption capability (lower reflection loss and small matching thickness) are evident with Ni-Fe coating on SiC fibers. For the composite SiC fibers coated with Ni-Fe thin films, a -35 dB reflection loss is predicted at 7.6 GHz with a matching thickness of 4 mm.

Comparison of vacuum metal deposition (VMD) and powder method for developing latent fingerprint on plastic envelope surface (플라스틱 봉투 표면에서 지문을 현출하기 위한 Vacuum Metal Deposition (VMD)과 분말법의 비교)

  • Kim, Chaewon;Lee, Narae;Kim, Taewon;Yu, Jeseol
    • Analytical Science and Technology
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    • v.33 no.3
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    • pp.159-166
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    • 2020
  • Vacuum metal deposition (VMD) is effective to develop latent fingerprints on non-porous and semi-porous surfaces. VMD can be used in cases when fingerprints that can not be developed by generalized techniques or deposited on difficult surfaces. The recommended surfaces for VMD techniques include vinyl, polymer bills, magnetic coated tickets, etc. In this study, the minimum amount of gold input was explored for developing fingerprints from at least 12 hours to up to 28 days after deposit fingerprint on the pink high density polyethylene envelope (HDPE) and low density polyethylene envelope (LDPE), which are mainly used as delivery envelopes. And the results were compared with the effects of black powder and fluorescent powder. In addition, delivery envelopes used for delivery were collected, then classified as HDPE and LDPE and pseudo-operation test was performed. As a result, VMD method developed good quality of fingerprints.

A Study on the PEM Electrolysis Characteristics Using Ti Mesh Coated with Electrocatalysts (Ti Mesh 처리 촉매전극을 이용한 고체고분자 전해질 전기분해 특성연구)

  • Sim, Kyu-Sung;Kim, Youn-Soon;Kim, Jong-Won;Han, Sang-Do
    • Transactions of the Korean hydrogen and new energy society
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    • v.7 no.1
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    • pp.29-37
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    • 1996
  • Alkaline water electrolysis has been commercialized as the only large-scale method for a long time to produce hydrogen and the technology is superior to other methods such as photochemical, thermochemical water splitting, and thermal decomposition method in view of efficiency and related technical problem. However, such conventional electrolyzer do not have high electric efficiency and productivity to apply to large scale hydrogen production for energy or chemical feedstocks. Solid polymer electrolyte water electrolysis using a perfluorocation exchange membrane as an $H^+$ ion conductor is considered to be a promising method, because of capability for operating at high current densities and low cell voltages. So, this is a good technology for the storage of electricity generated by photovoltaic power plants, wind generators and other energy conversion systems. One of the most important R&D topics in electrolyser is how to minimize cell voltage and maximize current density in order to increase the productivity of the electrolyzer. A commercialized technology is the hot press method which the film type electrocatalyst is hot-pressed to soild polymer membrane in order to eliminate the contact resistance. Various technologies, electrocatalyst formed over Nafion membrane surface by means of nonelectrolytic plating process, porous sintered metal(titanium powder) or titanium mesh coated with electrocatalyst, have been studied for preparation of membrane-electrocatalyst composites. In this study some experiments have been conducted at a solid polymer electrolyte water electrolyzer, which consisted of single cell stack with an electrode area of $25cm^2$ in a unipolar arrangement using titanium mesh coated with electrocatalyst.

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The Study on Structural Change and Improvement of Electrochemical Properties by Co-precipitation Condition of Li[Ni0.8Co0.15Al0.05]O2 Electrode (Li[Ni0.8Co0.15Al0.05]O2 전극의 공침 조건을 통한 구조적 변화와 전기적 특성의 향상 고찰)

  • Im, Jung-Bin;Son, Jong-Tae
    • Journal of the Korean Electrochemical Society
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    • v.14 no.2
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    • pp.98-103
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    • 2011
  • [ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.