The Experts below are selected from a list of 396 Experts worldwide ranked by ideXlab platform
Y.f. Cheng - One of the best experts on this subject based on the ideXlab platform.
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micro electrochemical characterization of the effect of applied stress on local anodic dissolution behavior of pipeline steel under near neutral ph condition
Electrochimica Acta, 2009Co-Authors: X Tang, Y.f. ChengAbstract:Abstract Local anodic dissolution behavior of smooth and pre-cracked X70 pipeline steel specimens under applied stress were investigated by micro-electrochemical measurements and numerical simulation. The results demonstrated that the anodic dissolution rate of steel is enhanced by applied tensile stress. Corrosion of the stressed steel is accompanied with the formation of a layer of Corrosion Product Deposit on electrode surface. However, the Deposit layer does not provide effective protection to the underlying steel for Corrosion attack due to its loose, porous structure. Under small tensile stress, the stress-enhanced dissolution of steel is not significant. With the increase of stress level up to 80% of yielding strength of steel, the activity of the steel increases remarkably, resulting in a significant enhancement of the anodic dissolution of steel. A stress concentration is developed at the crack-tip and enhances significantly the local anodic dissolution of steel. The stress effect factor at the crack tip is as high as 3.6 when a tensile force of 3000 N is applied on the pre-cracked specimen, while that for the low-stress area is 1.102 only. The local dissolution rate at the crack-tip is accelerated with the test time, which would be attributed to the fact that, along with continuous propagation of the crack, the stress concentration at the crack-tip is further increased, which, again, enhances local dissolution. This result reflects exactly the interaction of stress and anodic dissolution at crack-tip during SCC of steel.
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effects of Corrosion Product Deposit on the subsequent cathodic and anodic reactions of x 70 steel in near neutral ph solution
Corrosion Science, 2008Co-Authors: G Z Meng, C Zhang, Y.f. ChengAbstract:Abstract The effects of Corrosion Product Deposit on the subsequent anodic and cathodic reactions of X-70 steel in a near-neutral pH solution were investigated by localized electrochemical impedance spectroscopy (LEIS), scanning vibrating micro-electrode (SVME) and macroscopic EIS measurements as well as surface analysis technique. It is found that the Deposit layer formed on the steel surface is porous, non-compact in nature. The presence of a Corrosion Product layer would enhance adsorption, but significantly inhibit absorption and permeation of hydrogen atoms into steel. It is due to the porous structure of the Deposit that generates a spatial separation of cathodic and anodic reaction sites, resulting in an increased effective surface area for hydrogen adsorption and, simultaneously, a “blocking” effect on hydrogen absorption and permeation. The Deposit enhances greatly anodic dissolution of the steel, which is attributed to the adsorption of the intermediate species and the resultant “self-catalytic” mechanism for Corrosion of the steel in near-neutral pH solution. In the presence of Corrosion Product Deposit on the pipeline steel surface, pipeline Corrosion, especially pitting Corrosion, is expected to be enhanced. Stress Corrosion cracks could initiate from the Corrosion pits that form under Deposit. However, Deposit does not contribute to hydrogen permeation, although the hydrogen evolution is enhanced.
G Z Meng - One of the best experts on this subject based on the ideXlab platform.
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effects of Corrosion Product Deposit on the subsequent cathodic and anodic reactions of x 70 steel in near neutral ph solution
Corrosion Science, 2008Co-Authors: G Z Meng, C Zhang, Y.f. ChengAbstract:Abstract The effects of Corrosion Product Deposit on the subsequent anodic and cathodic reactions of X-70 steel in a near-neutral pH solution were investigated by localized electrochemical impedance spectroscopy (LEIS), scanning vibrating micro-electrode (SVME) and macroscopic EIS measurements as well as surface analysis technique. It is found that the Deposit layer formed on the steel surface is porous, non-compact in nature. The presence of a Corrosion Product layer would enhance adsorption, but significantly inhibit absorption and permeation of hydrogen atoms into steel. It is due to the porous structure of the Deposit that generates a spatial separation of cathodic and anodic reaction sites, resulting in an increased effective surface area for hydrogen adsorption and, simultaneously, a “blocking” effect on hydrogen absorption and permeation. The Deposit enhances greatly anodic dissolution of the steel, which is attributed to the adsorption of the intermediate species and the resultant “self-catalytic” mechanism for Corrosion of the steel in near-neutral pH solution. In the presence of Corrosion Product Deposit on the pipeline steel surface, pipeline Corrosion, especially pitting Corrosion, is expected to be enhanced. Stress Corrosion cracks could initiate from the Corrosion pits that form under Deposit. However, Deposit does not contribute to hydrogen permeation, although the hydrogen evolution is enhanced.
C Zhang - One of the best experts on this subject based on the ideXlab platform.
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effects of Corrosion Product Deposit on the subsequent cathodic and anodic reactions of x 70 steel in near neutral ph solution
Corrosion Science, 2008Co-Authors: G Z Meng, C Zhang, Y.f. ChengAbstract:Abstract The effects of Corrosion Product Deposit on the subsequent anodic and cathodic reactions of X-70 steel in a near-neutral pH solution were investigated by localized electrochemical impedance spectroscopy (LEIS), scanning vibrating micro-electrode (SVME) and macroscopic EIS measurements as well as surface analysis technique. It is found that the Deposit layer formed on the steel surface is porous, non-compact in nature. The presence of a Corrosion Product layer would enhance adsorption, but significantly inhibit absorption and permeation of hydrogen atoms into steel. It is due to the porous structure of the Deposit that generates a spatial separation of cathodic and anodic reaction sites, resulting in an increased effective surface area for hydrogen adsorption and, simultaneously, a “blocking” effect on hydrogen absorption and permeation. The Deposit enhances greatly anodic dissolution of the steel, which is attributed to the adsorption of the intermediate species and the resultant “self-catalytic” mechanism for Corrosion of the steel in near-neutral pH solution. In the presence of Corrosion Product Deposit on the pipeline steel surface, pipeline Corrosion, especially pitting Corrosion, is expected to be enhanced. Stress Corrosion cracks could initiate from the Corrosion pits that form under Deposit. However, Deposit does not contribute to hydrogen permeation, although the hydrogen evolution is enhanced.
X Tang - One of the best experts on this subject based on the ideXlab platform.
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micro electrochemical characterization of the effect of applied stress on local anodic dissolution behavior of pipeline steel under near neutral ph condition
Electrochimica Acta, 2009Co-Authors: X Tang, Y.f. ChengAbstract:Abstract Local anodic dissolution behavior of smooth and pre-cracked X70 pipeline steel specimens under applied stress were investigated by micro-electrochemical measurements and numerical simulation. The results demonstrated that the anodic dissolution rate of steel is enhanced by applied tensile stress. Corrosion of the stressed steel is accompanied with the formation of a layer of Corrosion Product Deposit on electrode surface. However, the Deposit layer does not provide effective protection to the underlying steel for Corrosion attack due to its loose, porous structure. Under small tensile stress, the stress-enhanced dissolution of steel is not significant. With the increase of stress level up to 80% of yielding strength of steel, the activity of the steel increases remarkably, resulting in a significant enhancement of the anodic dissolution of steel. A stress concentration is developed at the crack-tip and enhances significantly the local anodic dissolution of steel. The stress effect factor at the crack tip is as high as 3.6 when a tensile force of 3000 N is applied on the pre-cracked specimen, while that for the low-stress area is 1.102 only. The local dissolution rate at the crack-tip is accelerated with the test time, which would be attributed to the fact that, along with continuous propagation of the crack, the stress concentration at the crack-tip is further increased, which, again, enhances local dissolution. This result reflects exactly the interaction of stress and anodic dissolution at crack-tip during SCC of steel.
Sara Valizadeh - One of the best experts on this subject based on the ideXlab platform.
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investigation on a Corrosion Product Deposit layer on a boiling water reactor fuel cladding
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2010Co-Authors: A. V. Orlov, R Restani, G Kuri, Christian Degueldre, Sara ValizadehAbstract:Abstract Recent investigations on the complex Corrosion Product Deposits on a boiling water reactor (BWR) fuel cladding have shown that the observed layer locally presents unexpected magnetic properties. The magnetic behaviour of this layer and its axial variation on BWR fuel cladding is of interest with respect to non-destructive cladding characterization. Consequently, a cladding from a BWR was cut at elevations of 810 mm, where the layer was observed to be magnetic, and of 1810 mm where it was less magnetic. The samples were subsequently analyzed using electron probe microanalysis (EPMA), magnetic analysis and X-ray techniques (μXRF, μXRD and μXAFS). Both EPMA and μXRF have shown that the observed Corrosion Deposit layer which is situated on the Zircaloy Corrosion layer consists mostly of 3-d elements’ oxides (Fe, Zn, Ni and Mn). The distribution of these elements within the investigated layer is rather complex and not homogeneous. The main phases identified by 2D μXRD mapping inside the layer are hematite and spinel phases with the common formula MxFey(M(1−x)Fe(2−y))O4, where M = Zn, Ni, Mn. It has been shown that the solid solutions of these phases were obtained with rather large differences between the parameter cell of the known spinels (ZnFe2O4, NiFe2O4 and MnFe2O4) and the investigated material. The comparison of EPMA with μXRD analysis shows that the ratio of Fe2O3/MFe2O4 (M = Zn, Ni, Mn) phases in the lower sample equals ∼1/2 and in the higher one ∼1/1 within the analyzed volume of the samples. It has been shown that this ratio, together with the thickness of the Corrosion Product Deposit layer, effect its magnetic properties.
