• Title/Summary/Keyword: A321

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ON FUZZY BI-IDEALS IN SEMIGROUPS

  • Chon, Inheung
    • Korean Journal of Mathematics
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    • v.19 no.3
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    • pp.321-330
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    • 2011
  • We characterize the fuzzy bi-ideal generated by a fuzzy subset in a semigroup and the fuzzy bi-ideal generated by a fuzzy subset A such that $A{\subseteq}A^2$ in a semigroup with an identity element. Our work generalizes the characterization of fuzzy bi-ideals by Mo and Wang ([8]).

Variations of Micro-Structures and Mechanical Properties of Ti/STS321L Joint Using Brazing Method (브레이징을 이용한 Ti/STS321L 접합체의 미세조직과 기계적 특성의 변화)

  • 구자명;정우주;한범석;권상철;정승부
    • Journal of Welding and Joining
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    • v.20 no.6
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    • pp.106-106
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    • 2002
  • This study investigated variations of micro-structures and mechanical properties of Ti / STS321L joint with various bonding temperature and time using brazing method. According to increasing bonding temperature and time, it was observed that the thickness of their reaction layer increased due So increasing diffusion rate and time. From the EPMA results, Ti diffused to the STS321L substrate according to increasing bending time to 30min. Hardness of bonded interface increased with increasing bonding temperature and time due to increasing their oxides and intermetallic compounds. XRD data indicated that Ag, Ag-Ti intermetallic compounds, TiAg and Ti₃Ag and titanium oxide, TiO₂were formed in interface. In tensile test, it was found that the tensile strength had a maximum value at the bonding temperature of 900℃ and time of 5min, and tensile strength decreased over bonding time of 5min. The critical thickness of intermetallic compounds was observed to about 30㎛, because of brittleness from their excessive intermetallic compounds and titanium oxide, and weakness from void.

Variations of Micro-Structures and Mechanical Properties of Ti/STS321L Joint Using Brazing Method (브레이징을 이용한 Ti/STS321L 접합체의 미세조직과 기계적 특성의 변화)

  • 구자명;정우주;한범석;권상철;정승부
    • Journal of Welding and Joining
    • /
    • v.20 no.6
    • /
    • pp.830-837
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    • 2002
  • This study investigated variations of micro-structures and mechanical properties of Ti / STS321L joint with various bonding temperature and time using brazing method. According to increasing bonding temperature and time, it was observed that the thickness of their reaction layer increased due So increasing diffusion rate and time. From the EPMA results, Ti diffused to the STS321L substrate according to increasing bending time to 30min. Hardness of bonded interface increased with increasing bonding temperature and time due to increasing their oxides and intermetallic compounds. XRD data indicated that Ag, Ag-Ti intermetallic compounds, TiAg and $Ti_3Ag$ and titanium oxide, $TiO_2$ were formed in interface. In tensile test, it was found that the tensile strength had a maximum value at the bonding temperature of $900^{\circ}C$ and time of 5min, and tensile strength decreased over bonding time of 5min. The critical thickness of intermetallic compounds was observed to about $30\mu\textrm{m}$, because of brittleness from their excessive intermetallic compounds and titanium oxide, and weakness from void.

Investigation on Electrolytic Corrosion Characteristics with the Variation of Current Density of 5083-H321 Aluminum Alloy in Seawater (5083-H321 알루미늄 합금의 해수 내 전류밀도의 변화에 따른 전식 특성 연구)

  • Kim, Young-Bok;Kim, Seong-Jong
    • Journal of the Korean institute of surface engineering
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    • v.52 no.1
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    • pp.23-29
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    • 2019
  • Electrolytic corrosion of the ship's hull can be occurred due to stray current during welding work using shore power and electrical leakage using shore power supply. The electrolytic corrosion characteristics were investigated for Al5083-H321 through potentiodynamic polarization and galvanostatic corrosion test in natural seawater. Experiments of electrolytic corrosion were tested at various current densities ranging from $0.01mA/cm^2$ to $10mA/cm^2$ for 30 minutes, and at various applied time ranging from 60 to 240 minutes. Evaluation of electrolytic corrosion was carried out by Tafel extrapolation, weight loss, surface analysis after the experiment. In the electrolytic corrosion characteristics of Al5083-H321 as the current density increased, the surface damage tended to proportionally increase. In the current density of $0.01mA/cm^2$ for a applied long time, the damage tended to grow on the surface. In the case of $10mA/cm^2$ current density for a applied long time, the damage progressed to the depth direction of the surface, and the amount of weight loss per hour increased to 4 mg/hr.