• Corrosion Science and Technology
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• 제22권3호
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• pp.137-152
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• 2023

Polarization behavior and corrosion inhibition of copper in acidic chloride solutions containing benzotriazole were studied. Pourbaix diagrams constructed for copper in NaCl solutions with different BTAH concentrations were used to understand the polarization behavior. Open circuit potential (OCP) depended not only on chloride concentration, but also on whether a CuBTA layer was formed on the copper surface. Only when the (pH, OCP) was located well in the CuBTA region of the Pourbaix diagram, a stable corrosion inhibiting CuBTA layer was formed, which was confirmed by X-ray Photoelectron Spectroscopy (XPS) and a long-term corrosion test. The OCP for the CuBTA layer decreased logarithmically with increasing [Cl^-] activity in the solution. A minimum BTAH concentration required to form a CuBTA layer for a given NaCl concentration and pH were determined from the Pourbaix diagram. It was found that 320 ppm BTAH solution could be used to form a corrosion-inhibiting CuBTA layer inside the corrosion pit in the sprinkler copper tube, successfully reducing water leakage rate of copper tubes. These experimental results could be used to estimate water chemistry inside a corrosion pit.

• Transactions on Electrical and Electronic Materials
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• 제7권3호
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• pp.108-111
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• 2006

The oxidizer-induced corrosion state and microstructure of surface passive metal-oxide layer greatly influenced on the removal rate of tungsten film according to the slurry chemical composition of different mixed oxidizers. In this paper, the actual polishing mechanism and pH-potential equilibrium diagram obtained from potentiodynamic polarization curve were electrochemically compared. An electrochemical corrosion effect implies that slurries with the highest removal rate (RR) have the high dissolution rate.

• Journal of Welding and Joining
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• 제4권3호
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• pp.58-71
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• 1986

Mechanical and corrosion property of duplex stainless steel weldments made by the GTAW and SMAW process were studied. Fracture toughness, general and local corrosion resistance of GTAW and SMAW weldments were evaluated in terms of Charpy V notch impact test, anodic polarization diagram, pitting corrosion rate, respectively. SMA weld metal showed much lower impact toughness and higher ductile-brittle transition temperature than GTA weld metal. Fractographic and EDX analysis on fracture surface of SMA weld metal demonstrated the existence of (Si, Ti), oxide in large amounts. Potentiodynamic anodic polarization diagram of GMA weld metal showed much lower passive current density than SMA weld metal in 4% $H_2/SO_4$ solution. And pitting corrosion rate test showed the same tendency. Relating the microstructure, chemistry and property, it can be concluded that GTA weld metal gives better toughness due to lower oxygen content, i.e. lower inclusion content, and better corrosion resistance due to higher Pitting Index(PI) than SMA weld metal.

• 한국세라믹학회지
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• 제49권2호
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• pp.142-145
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• 2012

In order to investigate the surface SHG, (110) pure STO single crystals were exposed to a reducing atmosphere to induce the reduction of the Ti ion and the release of oxygen from the lattice compensating the reduction of the Ti ions. The anisotropy and asymmetry of SHG intensity explains a slight shrinkage. The incoming fundamental wave was polarized either in the $p$-in or $s$-in to the plane of incidence for the reflection geometry. The SH polarization diagram could be described by the electric dipole and/or quadrupole contribution of reduced STO single crystal surface.

• 천문학회보
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• 제39권1호
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• pp.62.2-62.2
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• 2014

We compiled near-infrared photometric and polarimetric catalog of sources in ~3 $9^{\prime}{\times}69^{\prime}$ size field in the eastern side of the Large Magellanic Cloud (LMC). This catalog lists all 1969 sources which are brighter than 14 mag and which signal to noise ratio of degree of polarization is greater than 3 in the J, H, and Ks bands. The photometric and polarimetric data were simultaneously obtained in J, H, and Ks bands using SIRPOL, an imaging polarimeter of the InfraRed Survey Facility (IRSF), in 2008 December and 2011 December. We classified the objects into several groups based on their locations on the color-magnitude diagram and compared their general properties of polarization. We measured wavelength dependence of this field to verify interstellar polarization of the LMC which occurred from the dichroic extinction. We also discuss the polarization structure in this field with the results from molecular cloud studies.

• 대한원격탐사학회지
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• 제25권3호
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• pp.255-261
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• 2009

A new polarimetric SAR image classification technique based on the degree of polarization (DoP) and the co-polarized phase-difference (CPD) is presented in this paper. Since the DoP and the CPD of a scattered wave provide information on the randomness of the scattering and the type of scattering mechanisms, at first, the statistics of the DoP and CPD are examined with measured polarimetric SAR image data. Then, a DoP-CPD diagram with appropriate boundaries between six different classes is developed based on the SAR image. The classification technique is verified using the JPL AirSAR and ALOS PALSAR polarimetric data. The technique may have capability to classify an SAR image into six major classes; a bare surface, a village, a crown-layer short vegetation canopy, a trunk-layer short vegetation canopy, a crown-layer forest, and a trunk-dominated forest.

• 수산해양교육연구
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• 제15권2호
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• pp.176-183
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• 2003

Recently, with the tendency of lightening, high-strength and high-speed in the marine industries such as marine structures, ships and propellers, it is rapidly enlarged the use of the aluminium alloy. Therefore, there occurs much interest in the study on corrosion characteristics of aluminium alloy. This paper was studied on the corrosion characteristics of Al-Mg alloy propeller used for a coasting vessel. Under the various pH of marine environment, the corrosion test of Al-Mg alloy was carried out. And thus polarization resistance, corrosion potential, and current density behavior of Al-Mg alloy and galvanic corrosion behavior of Al-brass and Al-Mg alloy coupled Al 5086 and SS 400 for hull were investigated. The main results are as following: 1. The corrosion potential of Al-brass propeller is more nobel than materials for hull, but that of Al-Mg alloy propeller is low or similar to materials for hull. Therefore, the galvanic corrosion of hull due to Al-Mg propeller don't occur. 2. The polarization resistance of Al-Mg alloy in sea water of pH 4 is highest, and corrosion current density of Al-Mg propeller is the most controlled. 3. As pH value decreases, potential showed Evans polarization diagram approaches cathodic potential. The corrosion current density of Al-Mg alloy is controlled to anodic reaction rate, therefore, the corrosion reaction of Al-Mg alloy is anodic control.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.29-32
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• 2008

In this paper, we propose one unsupervised classification technique using the degree of polarization (DoP) and the co-polarized phase-difference (CPD) statistics, instead of the entropy and alpha. It is shown that the DoP is closely related to the entropy, and the CPD to the alpha. The DoP explains the feature how much the effect of multiple reflections is contained. Hence, the DoP could be used as an important factor for classifying classes. The CPD can also be computed from the measured Mueller matrix elements. For the smooth surface scattering, the CPD is about $0^{\circ}$, and for dihedral-type scattering, the CPD is about $180^{\circ}$. A DoP-CPD diagram with appropriate boundaries between six different classes is developed based on the SAR image. The classification results are compared with the existing Entropy-alpha diagram as well as the IPL-AirSAR polarimetric data. The technique may have capability to classify an SAR image into six major classes; a bare surface, a village, a crown-layer short vegetation canopy, a trunk-layer short vegetation canopy, a crown-layer forest, and a trunk-dominated forest. Based on the DoP and CPD analysis, a simple three-component decomposition technique was also proposed.

• 한국표면공학회지
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• 제40권1호
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• pp.16-22
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• 2007

Recently, mesoporous metallic materials are becoming more and more important in various applications like catalysts, electrochemical detectors, batteries, and fuel cells because of their high surface area. Among the various methods for manufacturing mesoporous structure, surfactant templating method followed by electroplating has been tried in this study. A mesoporous metallic film was prepared by electrodeposition from electroplating solution mixed with surfactant template. Nonionic type lyotropic liquid crystalline surfactant, Brij56, and nickel acetate based solution were selected as a template material and electroplating solution, respectively. To determine the content of surfactant forming a hexagonal column structure, the phase diagram of electroplating solution and surfactant mixture has been exploited by polarized optical microscopy equipped with heating and cooling stage. Nickel films were electroplated on Cu foil by stepwise potential input method to alleviate the concentration polarization occurred during the electroplating process. TEM and XRD analyses were performed to characterize the size and shape of mesostructures in manufactured nickel films, and electrochemical characterization was also carried out using cyclic voltammetry.

• 천문학회지
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• 제44권4호
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• pp.135-142
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• 2011

A $200'{\times}200'$ region around 30 Doradus in the Large Magellanic Cloud (LMC) is observed and analyzed in the near-infrared. We obtain polarimetry data in the J, H, and Ks bands using the SIRIUS polarimeter SIRPOL at the Infrared Survey Facility 1.4 m telescope. We measure the Stokes parameters of 2562 point-like sources to derive the degree of polarization and the polarization position angles. We discuss the statistics of the groups classified by color-magnitude diagram and proper motions of the sources, in order to separate the Galactic foreground sources from those present in the LMC. We notice that groups classified by the proper motion data show a tendency towards different polarimetric properties.