• Title/Summary/Keyword: Additive materials

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Spheroidization of Enamel Powders by Radio Frequency Plasma Treatment and Application to Additive Manufacturing (RF 플라즈마 처리를 이용한 칠보 유약 분말의 구상화 및 적층 제조 공정 적용)

  • Kim, Ki-Bong;Yang, Dong-Yeol;Kim, Yong-Jin;Choe, Jungho;Kwak, Ji-Na;Jung, Woo-Hyung
    • Journal of Powder Materials
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    • v.27 no.5
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    • pp.388-393
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    • 2020
  • The enamel powders used traditionally in Korea are produced by a ball-milling process. Because of their irregular shapes, enamel powders exhibit poor flowability. Therefore, polygonal enamel powders are only used for handmade cloisonné crafts. In order to industrialize or automate the process of cloisonné crafts, it is essential to control the size and shape of the powder. In this study, the flowability of the enamel powders was improved using the spheroidization process, which employs the RF plasma treatment. In addition, a simple grid structure and logo were successfully produced using the additive manufacturing process (powder bed fusion), which utilizes spherical enamel powders. The additive manufacturing technology of spherical enamel powders is expected to be widely used in the field of cloisonné crafting in the future.

Effect of Additive Powder on Microstructural Evolutions and Mechanical Properties of the Wide-gap Brazed Region in IN738 superalloy (초내열합금 wide-gap 브레이징부의 미세조직 및 기계적 성질 변화에 미치는 첨가금속분말의 영향)

  • Kim Y. H.;Kwun S. I.;Byeon J. W.;Lee W. S.
    • Korean Journal of Materials Research
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    • v.15 no.6
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    • pp.399-407
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    • 2005
  • The effect of IN738 additive powder on microstructure and mechanical properties of the wide-gap region brazed with BNi-3 filler metal powder was investigated. The wide-gap brazing was conducted in a vacuum of $2\times10^{-5}torr\;at\;1200^{\circ}C$ with various powder mixing ratios of additive to filler powders. The microstructures of the wide-gap brazed region were analyzed by SEM and AES. The region brazed with only BNi-3 filler metal powder had a microstructure consisted of proeutectic, binary eutectic and ternary eutectic structure, while that brazed with a mixture of IN738 additive powder and BNi-3 filler metal powder had a microstructure consisted of IN738 additive powder, binary eutectic of $Ni_3B-Ni$ solid solution and (Cr, W)B. The fracture strength of the wide-gap brazed region was about 680 MPa regardless of the additive powder mixing ratios. Cracks were initiated at the (Cr, W)B and binary eutectic of $Ni_3B-Ni$ solid solution, and propagated through them in the wide-gap brazed region, which lowered the fracture strength of the region.

Enhancement of Paper Characteristics by Polyvinyl Alcohol/Polyamide-epichlorohydrin Coating as a Complex Strength Additive (Polyvinyl Alcohol/Polyamide-epichlorohydrin 복합 지력증강제에 의한 종이 특성 향상)

  • Jang, Yunjae;Lee, Hwaljong;Kang, Ho-Jong
    • Polymer(Korea)
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    • v.38 no.5
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    • pp.620-625
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    • 2014
  • The effect of polyvinyl alcohol/polyamide-epichlorohydrin (PVA/PAE) complex strengthening additive on dry and wet strength and surface properties of paper was investigated. The enhancements of dry and wet strength and dimensional stability were found when PVA/PAE was applied as a complex strengthening additive compared with the cases of applying individual PVA or PAE. This was understood as physical crosslinking between PVA and PAE in the PVA/PAE complex strength additive. This complex strengthening additive also lowered surface roughness and increased sizing. As a result, PVA/PAE complex strengthening additive provided the distinctive gain dot in printed papers.

Enhanced Machinability of Sinter-hardenable PM Steels

  • Lindsley, Bruce;Schade, Chris;Fillari, George
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.299-300
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    • 2006
  • Machining of sinter-hardened PM steels provides a challenge for part makers. To facilitate machining of these materials, a new additive (MA) has been developed to increase tool life during the machining process. Hard turning tests were performed to evaluate the effect of this new additive. Sintered compacts with the MA additive were compared to compacts without a machining aid and to compacts that contained the MnS additive. This paper discusses the improvement in machinability with this new additive in sinter-hardenable PM steels.

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Study on Corrosion Properties of Additive Manufactured 316L Stainless Steel and Alloy 625 in Seawater

  • Jung, Geun-Su;Park, Yong-Ha;Kim, Dae-Jung;Lim, Chae-Seon
    • Corrosion Science and Technology
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    • v.18 no.6
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    • pp.258-266
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    • 2019
  • The objective of this study was to evaluate corrosion resistance of additive manufactured 316L stainless steel and alloy 625 powders widely used in corrosion resistance alloys of marine industry in comparison with cast alloys. Directed Energy Deposition (DED) method was used in this work for sample production. DED parameter adjustment was also studied for optimum manufacturing and for minimizing the influence of defects on corrosion property. Additive manufactured alloys showed lower corrosion resistance in seawater compared to cast alloys. The reason for the degradation of anti-corrosion property was speculated to be due to loss of microstructural integrity intrinsic to the additive manufacturing process. Application of heat treatment with various conditions after DED was attempted. The effect of heat treatments was analyzed with a microstructure study. It was found that 316L and alloy 625 produced by the DED process could recover their expected corrosion resistance when heat treated at 1200 ℃.

Research Trend of Additive Manufacturing Technology - A=B+C+D+E, add Innovative Concept to Current Additive Manufacturing Technology: Four Conceptual Factors for Building Additive Manufacturing Technology -

  • Choi, Hanshin;Byun, Jong Min;Lee, Wonsik;Bang, Su-Ryong;Kim, Young Do
    • Journal of Powder Materials
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    • v.23 no.2
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    • pp.149-169
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    • 2016
  • Additive manufacturing (AM) is defined as the manufacture of three-dimensional tangible products by additively consolidating two-dimensional patterns layer by layer. In this review, we introduce four fundamental conceptual pillars that support AM technology: the bottom-up manufacturing factor, computer-aided manufacturing factor, distributed manufacturing factor, and eliminated manufacturing factor. All the conceptual factors work together; however, business strategy and technology optimization will vary according to the main factor that we emphasize. In parallel to the manufacturing paradigm shift toward mass personalization, manufacturing industrial ecology evolves to achieve competitiveness in economics of scope. AM technology is indeed a potent candidate manufacturing technology for satisfying volatile and customized markets. From the viewpoint of the innovation technology adoption cycle, various pros and cons of AM technology themselves prove that it is an innovative technology, in particular a disruptive innovation in manufacturing technology, as powder technology was when ingot metallurgy was dominant. Chasms related to the AM technology adoption cycle and efforts to cross the chasms are considered.

Study on the Waterproofing Performance of FGD Gypsum Building Products from Inorganic-Organic Composite Additives

  • Ding, Yi;Fang, Youchun;Ren, Qifang;Fang, Hui;Zhang, Qicai;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.25 no.11
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    • pp.590-597
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    • 2015
  • In this article, poly methyl triethoxy silane was compounded with an inorganic waterproof admixture at a certain ratio to improve the performance of gypsum products; a new type of high-efficiency compound water-proofing additive was also investigated. Furthermore, the waterproof mechanism and the various properties on the hardened gypsum plaster were investigated in detail by XRD and SEM. The results show that the intenerate coefficient of gypsum plaster increased to more than 0.9; the water absorbing rate decreased to less than 10 %. Both the bending strength and the compressive strength of gypsum plaster increased by various degrees. The intenerate coefficient reached a maximum value of 0.73 and the strength of the samples showed almost no change when 5% cement alone was added. In this new type of the high-efficiency compound with waterproof additive, the optimal technological parameters for formulas were obtained to be: 5% cement, 18 % mineral powder, and 0.8% poly methyl triethoxy silane, to compound gypsum plaster. Meanwhile, the production of high performance gypsum as a building material has become possible.

Property of the Spheroidized Zr Powder by Radio Frequency Plasma Treatment (RF 플라즈마 처리법에 기반한 기계적 밀링된 Zr 분말의 구형화에 따른 특성 변화)

  • Lee, Yukyeong;Choi, Mi-Sun;Park, Eon Byeong;Oh, Jeong Seok;Nam, Taehyun;Kim, Jung Gi
    • Journal of Powder Materials
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    • v.28 no.2
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    • pp.97-102
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    • 2021
  • Powder quality, including high flowability and spherical shape, determines the properties of additively manufactured products. Therefore, the cheap production of high-quality powders is critical in additive manufacturing. Radio frequency plasma treatment is an effective method to fabricate spherical powders by melting the surface of irregularly shaped powders; in the present work, mechanically milled Zr powders are spheroidized by radio frequency plasma treatment and their properties are compared with those of commercial Zircaloy-2 alloy powder. Spherical Zr particles are successfully fabricated by plasma treatment, although their flowability and impurity contents are poorer than those of the commercial Zircaloy-2 alloy powder. This result shows that radio-frequency plasma treatment with mechanically milled powders requires further research and development for manufacturing low-cost powders for additive manufacturing.

Effect of MgO-P2O5 Sintering Additive on Microstructure of Sintered Hydroxyapatite (HAp) Bodies and Their In-Vitro Study

  • Lee, Byong-Taek;Youn, Hyeong-Chul;Lee, Chi-Woo;Song, Ho-Yeon
    • Korean Journal of Materials Research
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    • v.17 no.2
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    • pp.100-106
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    • 2007
  • The effects of $MgO-P_2O_5$ based sintering additive on the microstructure and material and biological properties of hydroxyapatite $(HAp,\;Ca_{10}(PO_4)_6(OH)_2)$ ceramic were investigated using XRD, SEM and TEM techniques. The $MgO-P_2O_5$ sintering additive improved the material properties and increased the grain size in the sintered HAp bodies. As the content of sintering additive increased over 4 wt%, a small amount of the HAp phase was decomposed and transformed to ${\beta}-TCP$. In the 2 wt% $MgO-P_2O_5$ content HAp sintered body, the maximum values of density and hardness were respectively about 3.10 gm/cc and 657 HV. However, the maximum fracture toughness in the HAp body containing 8 wt% $MgO-P_{2}O_{5}$ was about $1.02MPa{\cdot}m^{1/2}$ due to the crack deflection effect. Human osteoblast like MG-63 cells and osteoclast like raw 264.7 cells were well grown and fully covered all of the HAp sintered bodies. The osteoblast cells were grown with spindle-shaped and the osteoclast cells had a grape-like round shape.

Additive manufacturing and mechanical properties evolution of biomedical Co-Cr-Mo alloys by using EBM method

  • Chiba, Akihiko;Kurosu, Shingo;Matsumoto, Hiroaki;Li, Yunping;Koizumi, Yuichiro
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2012.05a
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    • pp.56.1-56.1
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    • 2012
  • The microstructures and mechanical properties of Co-29Cr-6Mo alloy with C and N additions, produced by additive manufacturing using electron beam melting (EBM) method, were studied using X-ray diffraction, electron back scatter diffraction, transmission electron microscope, Vickers hardness tests, and tensile tests, focusing on the influences on the build direction and the various heat treatments after build. It is found that the microstructures for the as built specimens were changed from columnar to equiaxed grain structure with average grain size of approximately $10-20{\mu}m$ due to the heat treatment employing the reverse transformation from a lamellar (hcp + $Cr_2N$) phase to an fcc. Our results will contribute to the development of biomedical Ni-free Co-Cr-Mo-N-C alloys, produced by EBM method, with refined grain size and good mechanical properties, without requiring any hot workings.

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