• Title/Summary/Keyword: Surface modification

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Feasibility Study for Wear Resistance of Rails (레일의 내마모성에 대한 타당성 연구)

  • Chang, Seky;Pyun, Young Sik
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.23 no.6
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    • pp.576-579
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    • 2014
  • Rails are continuously exposed to severe environments due to increases in train service frequency, passing tonnage, and speed. Wear is one of the most common types of damage observed on rails. The surface of railsis heat treated to secure safety at critical sites, such as curved tracks or turnouts. Ultrasonic nanocrystal surface modification (UNSM), a new approach for rails, was examined to strengthen the rail surface. The effect of UNSM on the wear resistance of rail specimens was compared with that of heat treatment. Wear resistance was improved after UNSM treatment due to increased hardness and surface compressive residual stress.

Trend of Laser Cladding Technology in Material Processing (공구강의 내 마모성을 높여주는 레이저 클래딩 기술동향)

  • Kil, S.C.;Kim, H.T.;Kim, S.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.321-324
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    • 2008
  • The increasing interest in the surface modification by the laser cladding technology in the material processing is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency laser cladding technology. This paper covers recent technical trends of laser cladding technology including the COMPENDEX DB analysis.

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The Hardfacing Technology by PTA Overlaying Process (PTA 오버레이 공정을 이용한 산업설비부품의 표면경화기술)

  • Kil, S.C.;Kim, H.T.;Kim, S.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.358-361
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    • 2009
  • The increasing interest in the surface modification technology by the plasma transferred arc overlaying process in the material processing is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency plasma transferred arc overlaying technology. This paper covers recent technical trends of plasma transferred arc overlaying technology including the COMPENDEX DB analysis.

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Advancements in Polymer-Filler Derived Ceramics

  • Greil, Peter
    • Journal of the Korean Ceramic Society
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    • v.49 no.4
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    • pp.279-286
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    • 2012
  • Microstructure tailoring of filler loaded preceramic polymer systems offers a high potential for property improvement of Si-based ceramics and composites. Advancements in manufacturing of bulk materials by controlling microstructure evolution during thermal induced polymer-ceramic transforma-tion and polymer-filler reactions will be presented. Rate controlled pyrolysis, multilayer gradient laminate design and surface modification by gas solid reaction are demonstrated to yield ceramic components of high fractional density and superior mechanical properties. Emerging fields of applications are presented.

The Study on Surface Modification of Alumina Membrane by CVD (CVD에 의한 알루미나 멤브레인의 표면개질에 관한 연구)

  • 이동호;최두진;현상훈;고광백
    • Journal of the Korean Ceramic Society
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    • v.32 no.12
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    • pp.1349-1356
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    • 1995
  • The change of permeation mechanism from Knudsen diffusion to micropore diffusion was observed after CVD modification of an alumina-sol coated alumina support which was prepared by slip coating process. Permselectivities of He/N2, H2/N2, and CO2/N2 were 5.67, 5.02, and 1.44, respectively. These values were higher than those under Knudsen diffusion controlled region.

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Surface Modification Studies by Atomic Force Microscopy for Ar-Plasma Treated Polyethylene

  • Seo, Eun-Deock
    • Macromolecular Research
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    • v.10 no.5
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    • pp.291-295
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    • 2002
  • Atomic force microscopy(AFM) was used to study the polyethylene(PE) surfaces grafted and immobilized with acrylic acid by Ar plasma treatment. The topographical images and parameters including RMS roughness and Rp-v value provided an appropriate means to characterize the surfaces. The plasma grafting and immobilization method were a useful tool for the preparation of surfaces with carboxyl group. However, the plasma immobilization method turned out to have a limitation to use as a means of preparation of PE surface with specific functionalities, due to ablation effect during the Ar plasma treatment process.

Surface modification of polypropylene membrane to improve antifouling characteristics in a submerged membrane-bioreactor: Ar plasma treatment

  • Zhou, Jin;Li, Wei;Gu, Jia-Shan;Yu, Hai-Yin
    • Membrane and Water Treatment
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    • v.1 no.1
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    • pp.83-92
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    • 2010
  • To improve the antifouling characteristics of polypropylene hollow fiber microporous membranes in a submerged membrane-bioreactor for wastewater treatment, the surface-modification was conducted by Ar plasma treatment. Surface hydrophilicity was assessed by water contact angle measurements. The advancing and receding water contact angles reduced after the surface modification, and hysteresis between the advancing and receding water contact angles was enlarged after Ar plasma treatment due to the increased surface roughness after surface plasma treatment. After continuous operation in a submerged membrane-bioreactor for about 55 h, the flux recovery after water cleaning and the flux ratio after fouling were improved by 20.0 and 143.0%, while the reduction of flux was reduced by 28.6% for the surface modified membrane after 1 min Ar plasma treatment, compared to those of the unmodified membrane. Morphological observations showed that the mean membrane pore size after Ar plasma treatment reduced as a result of the deposition of the etched species; after it was used in the submerged membrane-bioreactor, the further decline of the mean membrane pore size was caused by the deposition of foulants. X-ray photoelectron spectroscopy and infrared spectroscopy confirmed that proteins and polysaccharide-like substances were the main foulants in the precipitate.

Anti-calcification of Bovine Pericardium for Bioprosthetic Heart Valves after Surface Modification with Hyaluronic Acid Derivatives

  • Hahn Sei Kwang;Ohri Rachit;Giachelli Cecilia M.
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.10 no.3
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    • pp.218-224
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    • 2005
  • Surface modification of glutaraldehyde fixed bovine pericardium (GFBP) was success­fully carried out with hyaluronic acid (HA) derivatives. At first, HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional group into the carboxyl group of HA backbone. Then, GFBP was surface modified by grafting HA-ADH to the free aldehyde groups on the tissue and the subsequent HA-ADH hydrogel coating. HA-ADH hydrogels could be prepared through selective crosslinking at low pH between hydrazide groups of HA-ADH and crosslinkers containing succinimmidyl moieties with minimized protein denaturation. When HA­ADH hydrogels were prepared at low pH of 4.8 in the presence of erythropoietin (EPO) as a model protein, EPO release was continued up to $85\%$ of total amount of loaded EPO for 4 days. To the contrary, only $30\%$ of EPO was released from HA-ADH hydrogels prepared at pH=7.4, which might be due to the denaturation of EPO during the crosslinking reaction. Because the carboxyl groups on the glucuronic acid residues are recognition sites for HA degradation by hyaluronidase, the HA-ADH hydrogels degraded more slowly than HA hydrogels prepared by the crosslinking reaction of divinyl sulfone with hydroxyl groups of HA. Following a two-week subcutaneous implantation in osteopontin-null mice, clinically significant levels of calcification were observed for the positive controls without any surface modification. However, the calcification of surface modified GFBP with HA-ADH and HA-ADH hydrogels was drastically reduced by more than $85\%$ of the positive controls. The anti-calcification effect of HA surface modification was also confirmed by microscopic analysis of explanted tissue after staining with Alizarin Red S for calcium, which followed the trend as observed with calcium quantification.

Interfacial Characteristics of Polymeric Composite Materials (고분자 복합재료의 계면특성)

  • Park Soo-Jin;Seo Min-Kang
    • Polymer(Korea)
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    • v.29 no.3
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    • pp.221-230
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    • 2005
  • Interfacial interactions and interphases played a key role in multicomponent materials irrespectively of the number and type of their components or their actual structure. They were equally important in particulate filled polymer, polymer blends, fibers-reinforced advanced composites, nanocomposites or biomimetic materials. Recognition of the role of the main factors influencing interfacial adhesion and proper surface modification could lead to significant progress in many fields of research and development, as well as in related technologies. Although the role and importance of interfaces and interphases were the same for all multicomponent materials, the surface modification could be always selected according to the objectives targeted, as well as to the characteristics of the particular system. In this wort therefore, several types of surface modification were performed to improve the interfacial interactions between two components in composite system and their results for the composites were investigated.