• Title/Summary/Keyword: Bare Metal

Search Result 115, Processing Time 0.025 seconds

Fatigue characteristics of spot welding between high strength steel and galvanized steel sheet (고장력 강판과 아연도금 강판문의 점용접 피로특성)

  • 서창민;강성수
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.12 no.4
    • /
    • pp.747-754
    • /
    • 1988
  • High strength steels (HS) of dual phase and monogalvanized steel sheets (GA ; plated plane, GAB ; bare plane0 were used to investigate the fatigue strengths of four kinds of single-spot-welded joint specimen under tensile-shear repeated load. The specimen is classified as the same mating metal specimen (HS*HS, GA*GAB) and different mating metal specimen (HS*GA, HS*GAB). Some of the results are ; (1) Static tensile load of single-spot-welded joint specimens is proportional to tensile strength of metal and rigidity of mating metal sheet. (2) Fatigue life of HS*HS specimens increased about 20% longer than that of GA*GAB specimens in low cycle range. (3) In different mating metal specimens, the fatigue life of HS*GA specimens increased about 84% more that of HS*HS specimens in high cycle range.

A Study on the Deposition Transfer state of Organic Thin Films(Arac.acid) (유기박막(Arac.acid)의 누적전이상태에 관한 연구)

  • Chung, Hun-Sang;Song, Jin-Won;Lee, Kyung-Sup;Jun, Yon-Su;Chon, Woo-Gi
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2001.05a
    • /
    • pp.57-60
    • /
    • 2001
  • The characterization of organic Metal/Insulator/Metal(MIM) devices were investigated from LB films. The physicochemical properties of the LB films were by UV absorption spectrum and AFM. We give pressure stimulation into organic thin films and then manufacture a device under the accumulation condition that the state surface pressure is 2, 10, 30[mN/ml The stable images are probably due to a strong interaction between the monolayer film and glass substrate. We are unable to obtain molecule resolution in images of the films but did see a marked contrast between images of the bare substrate and those with the network structure film deposited onto it.

  • PDF

Manipulation of Carbon Nanotube Tip Using Focused Ion Beam (집속이온빔을 이용한 탄소나노튜브 팁의 조작)

  • Yoon, Yeo-Hwan;Park, June-Ki;Han, Chang-Soo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.23 no.12 s.189
    • /
    • pp.122-127
    • /
    • 2006
  • This paper reports on the development of carbon nanotube tip modified with focused ion beam(FIB). We used an electric field which causes dielectrophoresis, to align and deposit CNTs on a metal-coated canning Probe Microscope (SPM) tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip was aligned toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for SPM.

Coating defects in polymer-coated drug-eluting stents

  • Bedair, Tarek M.;Cho, Youngjin;Park, Bang Ju;Joung, Yoon Ki;Han, Dong Keun
    • Biomaterials and Biomechanics in Bioengineering
    • /
    • v.1 no.3
    • /
    • pp.131-150
    • /
    • 2014
  • Vascular stenting has a great attention as a treatment for coronary arteries diseases as compared with percutaneous balloon angioplasty. In-stent restenosis and thrombosis are side effects resulting from using bare metal stent (BMS). Employing platelet therapy allowed to reduce the rate of thrombosis, however, the rate of restenosis remains a major problem. In 2002, drug-eluting stents (DESs) were introduced as an effort to reduce the restenosis. The commercially available DESs continue to suffer from coating defects that might lead to a series of adverse effects. Most importantly, multiple concerns remain regarding the polymer coating integrity on metal surfaces or the relation of polymer irregularities to longterm adverse events.

Using Focus Ion Beam Carbon Nanotube Tip Manipulation (Focus Ion Beam을 이용한 탄소나노튜브 팁의 조작)

  • Yoon Y.H.;Han C.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2006.05a
    • /
    • pp.461-462
    • /
    • 2006
  • This paper reports on the development of a scanning probe microscopy(SPM) tip with caborn nanotubes. We used an electric field which causes dielectrophoresis(DEP), to align and deposit CNTs on a metal-coated SPM tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip align toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for scanning probe microscopy.

  • PDF

Effect of Hydrodynamic Condition on the Electrochemical Behavior of Various Metals in 3.5 wt% NaCl Solution

  • Pan, Szu-Jung;Hadinata, Samuel-Sudibyo;Kao, Ruey-Chy;Tsai, Wen-Ta
    • Corrosion Science and Technology
    • /
    • v.14 no.5
    • /
    • pp.218-225
    • /
    • 2015
  • The electrochemical behaviors of various metals with and without diamond-like-carbon (DLC) coating in 3.5 wt% NaCl solution were investigated. The effect of hydrodynamic conditions was focused by employing a rotating disc electrode (RDE). The experimental results showed that each bare metal had a more positive corrosion potential and a higher corrosion rate due to enhanced oxygen transport at the higher rotating speed of the RDE. DLC coating caused a substantial increase in the corrosion resistance of all metals studied. However, localized corrosion was still found in the DLC-coated metal at sites where deposition defects existed. Surface morphology examination was performed after the electrochemical test to confirm the roles of hydrodynamic conditions and DLC coating.

Characteristics of the Topography Image of Polyurethane Polymer LB Films (폴리우레탄 고분자 LB막의 표면형상 이미지 특성)

  • Seo, Jeong-Yeul;Kim, Do-Kyun;Shin, Hoon-Kyu;Kwon, Young-Soo
    • Proceedings of the KIEE Conference
    • /
    • 2000.07c
    • /
    • pp.1708-1710
    • /
    • 2000
  • The synthesis and characterization of polymers for organic Metal/Insulator/Metal(MIM) devices were investigated from LB films. The physicochemical properties of the LB films were examined by UV absorption spectrum and AFM. The AFM images showed for network structure of polyurethane monolayer that the film formed an unsymmetry mesh with intermolecular interaction within the large scale. The stable images are probably due to a strong interaction between the monolayer film and Si substrate. We are unable to obtain molecular resolution in images of the films but did see a marked contrast between images of the bare substrate and those with the network structure film deposited onto it.

  • PDF

Electrocatalytic Reduction of Molecular Oxygen at Poly(1,8-diaminonaphthalene) and Poly(Co(II)-(1,8-diaminonaphthalene)) Coated Electrodes

  • Park, Hyun;Kwon, Tae-guen;Park, Deog-Su;Shim, Yoon-Bo
    • Bulletin of the Korean Chemical Society
    • /
    • v.27 no.11
    • /
    • pp.1763-1768
    • /
    • 2006
  • The application of poly(Co(II)-(1,8-diaminonaphthalene))(poly(Co-DAN)) and poly(1,8-diaminonaphthalene) (Poly(1,8-DAN)) to the electrocatalytic reduction of molecular oxygen was investigated, which were electrochemically grown by the potential cycling method on the glassy carbon electrodes. The reduction of oxygen at the polymer and its metal complex polymer coated electrodes were irreversible and diffusion controlled. The Poly(1,8-DAN) and Poly(Co-DAN) films revealed the potential shifts for the oxygen reduction to 30 mV and 110 mV, respectively, in an aqueous solution, compared with that of the bare electrode. Hydrodynamic voltammetry with a rotating ring-disk electrode showed that Poly(1,8-DAN) and Poly(Co-DAN) coated electrodes converted respectively 84% and 22% of $O_2$ to $H_2O$ via a four electron reduction pathway.

Electrocatalytic Reduction of Thionyl Chloride by Schiff Base Metal(II) Complexes (1)

  • Sin, Mi Suk;Kim, U Seong;Jo, Gi Hyeong;Choe, Yong Guk
    • Bulletin of the Korean Chemical Society
    • /
    • v.16 no.3
    • /
    • pp.205-210
    • /
    • 1995
  • Catalytic effects of various Schiff base metal(II) complexes on the reduction of thionyl chloride at glassy carbon electrode are evaluated by determining the kinetic parameters from cyclic voltammetry technique. The charge transfer process is affected strongly by the concentration of catalysts during the reduction of thionyl chloride. The catalytic effects are shown by both a shift of the reduction potential for thionyl chloride toward more positive direction and an increase in peak current. The diffusion coefficient value, Do, of the 8.17 ${\times}$ 10-9 $cm^2/s$ was observed at the bare glassy carbon electrode, whereas larger values (0.9-1.09 ${\times}$ 10-8 $cm^2/s$) were observed at the catalyst supported glassy carbon electrode. Significant improvements in the cell performance have been noted in terms of both exchange rate constants and current densities at glassy carbon electrode.

Effect of Transition Metal(II)-N,N-Bis(salicylaldehyde)phenylenediimines on the Electrochemical Reduction of Thionyl Chloride

  • 김현수;최용국;조기형;국성근;우희권
    • Bulletin of the Korean Chemical Society
    • /
    • v.17 no.3
    • /
    • pp.223-227
    • /
    • 1996
  • Catalytic effects of transition metal (Co2+, Ni2+) complexes of N,N-bis(salicylaldehyde)-o-phenylenediimine (SOPD), N,N-bis(salicylaldehyde)-m-phenylenediimine (SMPD), and N,N-bis(salicylaldehyde)-p-phenylenediimine (SPPD), on the reduction of thionyl chloride at glassy carbon electrode, are evaluated by determining the kinetic parameters with cyclic voltammetric technique. The charge transfer process for the reduction of thionyl chloride is strongly affected by the concentration of the catalysts. Some quadridentate Schiff base-M(Ⅱ) complexes show sizable catalytic activities for the reduction of thionyl chloride. Catalytic effects of [M(Ⅱ)(SOPD)] complexes are slightly larger compared to [M(Ⅱ)2(SMPD)2] and [M(Ⅱ)2(SPPD)2] complexes. On those electrodes deposited with the catalysts, the observed exchange rate constants (ko) are in the range of 0.89-2.28 × 10-7 cm/s, while it is 1.24 × 10-7 cm/s on the bare glassy carbon electrode.