The Experts below are selected from a list of 26841 Experts worldwide ranked by ideXlab platform
Richard L Mccreery - One of the best experts on this subject based on the ideXlab platform.
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corrosion protection of untreated aa 2024 t3 in chloride solution by a chromate conversion coating monitored with raman spectroscopy
Journal of The Electrochemical Society, 1998Co-Authors: Jun Zhao, G S Frankel, Richard L MccreeryAbstract:The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft Alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands of pure CrO4 − 2 or Cr2O7 − 2 . Second, Raman spectroscopy was used to monitor migration of chromate species from a CCC film to an initially untreated Alloy Sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh Alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated Alloy Sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated Alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion
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Corrosion Protection of Untreated AA‐2024‐T3 in Chloride Solution by a Chromate Conversion Coating Monitored with Raman Spectroscopy
Journal of The Electrochemical Society, 1998Co-Authors: Jun Zhao, G S Frankel, Richard L MccreeryAbstract:The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft Alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands of pure CrO4 − 2 or Cr2O7 − 2 . Second, Raman spectroscopy was used to monitor migration of chromate species from a CCC film to an initially untreated Alloy Sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh Alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated Alloy Sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated Alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion
Takayuki Takasugi - One of the best experts on this subject based on the ideXlab platform.
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evaluation of surface modified ti 6al 4v Alloy by combination of plasma carburizing and deep rolling
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: N Tsuji, S Tanaka, Takayuki TakasugiAbstract:Abstract Plasma surface diffusion processes such as plasma-carburizing and nitriding have been used to improve tribological properties of titanium and its Alloys. However, the improvement of fatigue strength by these processes has not been successful due to brittleness introduced in the high-hardness surface layer and the disappearance of compressive residual stress and grain growth by heating. In this work, a Ti–6Al–4V Alloy Sample was plasma-carburized at a relatively low temperature to improve wear resistance, and then, deep-rolled to induce compressive residual stress. Scanning electron microscopy, optical microscopy, laser scanning microscopy, surface roughness tester, X-ray diffractometer, and micro-hardness tester were used to characterize the modified surface layer. The residual stress and work hardening state was analyzed by X-ray diffraction techniques. The effect of deep-rolling on fatigue strength and wear resistance of plasma-carburized Ti–6Al–4V Alloy was also investigated. The fatigue properties and wear resistance of Ti–6Al–4V Alloy modified by a combination of low-temperature plasma-carburizing and deep-rolling were significantly improved in comparison with those of the unmodified Ti–6Al–4V Alloy.
Jun Zhao - One of the best experts on this subject based on the ideXlab platform.
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corrosion protection of untreated aa 2024 t3 in chloride solution by a chromate conversion coating monitored with raman spectroscopy
Journal of The Electrochemical Society, 1998Co-Authors: Jun Zhao, G S Frankel, Richard L MccreeryAbstract:The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft Alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands of pure CrO4 − 2 or Cr2O7 − 2 . Second, Raman spectroscopy was used to monitor migration of chromate species from a CCC film to an initially untreated Alloy Sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh Alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated Alloy Sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated Alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion
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Corrosion Protection of Untreated AA‐2024‐T3 in Chloride Solution by a Chromate Conversion Coating Monitored with Raman Spectroscopy
Journal of The Electrochemical Society, 1998Co-Authors: Jun Zhao, G S Frankel, Richard L MccreeryAbstract:The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft Alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands of pure CrO4 − 2 or Cr2O7 − 2 . Second, Raman spectroscopy was used to monitor migration of chromate species from a CCC film to an initially untreated Alloy Sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh Alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated Alloy Sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated Alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion
Young Gun Ko - One of the best experts on this subject based on the ideXlab platform.
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Hybrid organic-inorganic coatings via electron transfer behaviour
Scientific Reports, 2017Co-Authors: Wail Al Zoubi, Young Gun KoAbstract:A novel method to functionalize the surface of inorganic coating by growing organic coating has been investigated based on microstructural interpretation, electrochemical assessment, and quantum chemical analysis. For this purpose, inorganic coating with magnesium aluminate, magnesium oxide, and titanium dioxide was prepared on magnesium Alloy via plasma electrolytic oxidation (PEO), and, then, subsequent dip-coating method was used to tailor organic coating using diethyl-5-hydroxyisophthalate (DEIP) as organic molecules. The incorporation of TiO_2 particles worked as a sealing agent to block the micro-defects which resulted mainly from the intense plasma sparks during PEO. In addition, such incorporation played an important role in enhancing the adhesion between inorganic and organic coatings. The use of DEIP as organic corrosion inhibitor resulted in a significant decrease in porosity of inorganic coating. Quantum chemical calculation was used to clarify the corrosion inhibition mechanism which was activated by introduction of DEIP. Thus, the electrochemical analysis based on potentiodynamic polarization and impedance spectroscopy tests in 3.5 wt% NaCl solution suggested that corrosion resistance of magnesium Alloy Sample was enhanced significantly due to a synergistic effect arising from the hybrid inorganic and organic coatings. This phenomenon was explained in relation to electron transfer behaviour between inorganic and organic coatings.
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effect of deformation temperature on microstructure and mechanical properties of az31 mg Alloy processed by differential speed rolling
Journal of Materials Science & Technology, 2015Co-Authors: Mosab Kaseem, Bong Kwon Chung, Kotiba Hamad, Hae Woong Yang, Young Gun KoAbstract:A differential-speed rolling (DSR) was applied to AZ31 magnesium Alloy Sample at different rolling temperatures of 473, 523, 573, and 623 K with 1-pass and 2-pass operations. The microstructural evolution and mechanical properties of the deformed Samples were investigated. The rolling temperature was found to be an important parameter affecting the microstructural development. After DSR at 473 K, the microstructure was more homogeneous than that obtained after deformation by equal-speed rolling (ESR). The fully recrystallized microstructures were generated after DSR at 573 and 623 K. As to mechanical properties, the yield strength (YS) and ultimate tensile strength (UTS) decreased monotonously with increasing rolling temperature. In contrast, the elongation of the DSR-deformed Samples was improved as the rolling temperature increased. The strain hardening exponent (n) calculated by Hollomon equation increased with increasing the rolling temperature, which would explain an increase in the uniform elongation.
G S Frankel - One of the best experts on this subject based on the ideXlab platform.
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corrosion protection of untreated aa 2024 t3 in chloride solution by a chromate conversion coating monitored with raman spectroscopy
Journal of The Electrochemical Society, 1998Co-Authors: Jun Zhao, G S Frankel, Richard L MccreeryAbstract:The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft Alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands of pure CrO4 − 2 or Cr2O7 − 2 . Second, Raman spectroscopy was used to monitor migration of chromate species from a CCC film to an initially untreated Alloy Sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh Alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated Alloy Sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated Alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion
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Corrosion Protection of Untreated AA‐2024‐T3 in Chloride Solution by a Chromate Conversion Coating Monitored with Raman Spectroscopy
Journal of The Electrochemical Society, 1998Co-Authors: Jun Zhao, G S Frankel, Richard L MccreeryAbstract:The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft Alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands of pure CrO4 − 2 or Cr2O7 − 2 . Second, Raman spectroscopy was used to monitor migration of chromate species from a CCC film to an initially untreated Alloy Sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh Alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated Alloy Sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated Alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion
