The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Zhiyong Liu - One of the best experts on this subject based on the ideXlab platform.
-
comparative study on the stress corrosion cracking of x70 pipeline steel in simulated shallow and deep sea environments
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Feilong Sun, Shuai Ren, Zhiyong LiuAbstract:Abstract The stress corrosion cracking (SCC) behavior of X70 steel in simulated shallow and deep sea environments was studied using potentiodynamic polarization measurement, a slow strain rate tensile (SSRT) test and scanning electron microscopy (SEM). The results indicate that the predominant Cathodic Reaction changes from an oxygen reduction Reaction to the hydrogen evolution Reaction as the dissolved oxygen (DO) content decreases. In the simulated deep sea environment, the SCC susceptibility of X70 steel decreased first, reached its lowest point at 15 MPa and then increased as the simulated sea hydrostatic pressure (HP) further increased. This is consistent with the regularity for the change of the Cathodic hydrogen evolution Reaction current density i H at E corr , which indicates that the HP may influence the SCC susceptibility of X70 steel by changing the permeated hydrogen concentration.
-
effect of strain rate on Cathodic Reaction during stress corrosion cracking of x70 pipeline steel in a near neutral ph solution
Journal of Materials Engineering and Performance, 2011Co-Authors: Zhiyong Liu, Y F ChengAbstract:The effect of strain rate on Cathodic Reactions of X70 pipeline steel during stress corrosion cracking in a near-neutral pH solution was investigated by electrochemical impedance spectroscope and potentiodynamic polarization curve measurements as well as slow strain rate tests. A local additional potential model was used to understand mechanistically the role of strain rate in electrochemical Cathodic Reaction. It was found that an application of elastic stress would not affect the electrochemical stable state of the steel specimen at a macroscopic scale. Under a weak Cathodic polarization, the interfacial charge-transfer process occurring on steel contains both Cathodic and anodic Reactions. Since the anodic Reaction process is still significant, localized dissolution could occur even at such a Cathodic potential, resulting in generation of corrosion pits. These pits could be the start sites to initiate stress corrosion cracks. Strain rate affects the corrosion Reaction, which is associated with the generation of dislocation emergence points and slip steps on the specimen surface, resulting in a negative local additional potential to enhance the Cathodic Reaction locally.
Y F Cheng - One of the best experts on this subject based on the ideXlab platform.
-
effect of strain rate on Cathodic Reaction during stress corrosion cracking of x70 pipeline steel in a near neutral ph solution
Journal of Materials Engineering and Performance, 2011Co-Authors: Zhiyong Liu, Y F ChengAbstract:The effect of strain rate on Cathodic Reactions of X70 pipeline steel during stress corrosion cracking in a near-neutral pH solution was investigated by electrochemical impedance spectroscope and potentiodynamic polarization curve measurements as well as slow strain rate tests. A local additional potential model was used to understand mechanistically the role of strain rate in electrochemical Cathodic Reaction. It was found that an application of elastic stress would not affect the electrochemical stable state of the steel specimen at a macroscopic scale. Under a weak Cathodic polarization, the interfacial charge-transfer process occurring on steel contains both Cathodic and anodic Reactions. Since the anodic Reaction process is still significant, localized dissolution could occur even at such a Cathodic potential, resulting in generation of corrosion pits. These pits could be the start sites to initiate stress corrosion cracks. Strain rate affects the corrosion Reaction, which is associated with the generation of dislocation emergence points and slip steps on the specimen surface, resulting in a negative local additional potential to enhance the Cathodic Reaction locally.
-
Cathodic Reaction kinetics and its implication on flow assisted corrosion of aluminum alloy in aqueous ethylene glycol solution
Journal of Applied Electrochemistry, 2009Co-Authors: Y Liu, Y F ChengAbstract:The Cathodic Reaction kinetics and anodic behavior of Al alloy 3003 in aerated ethylene glycol–water solution, under well-controlled hydrodynamic conditions, were investigated by various measurements using a rotating disk electrode (RDE). The transport and electrochemical parameters for Cathodic oxygen reduction were fitted and determined. The results demonstrate that the Cathodic Reaction is a purely diffusion-controlled process within a certain potential region. The experimentally fitted value of diffusion coefficient of oxygen is 3.0 × 10−8 cm2 s−1. The dependence of Cathodic current on rotation speed was in quantitative agreement with Levich equation. At potentials more positive than the diffusion controlled region, the Cathodic process was controlled by both diffusion and electrochemical kinetics. The electrochemical Reaction rate constant, k 0, was determined to be 1.1 × 10−9 cm s−1. There is little effect of electrode rotation on anodic behavior of Al alloy during stable pitting. However, fluid hydrodynamics play a significant role in formation of the oxide film and the Al alloy passivity. An enhanced electrode rotation would increase the mass-transfer rate of solution, and thus the oxygen diffusion towards the electrode surface for reduction Reaction. The generated hydroxide ions are favorable to the formation of Al oxide film on electrode surface.
Koichi Yamada - One of the best experts on this subject based on the ideXlab platform.
-
Cathodic Reaction mechanism of dense la0 6sr0 4coo3 and la0 81sr0 09mno3 electrodes for solid oxide fuel cells
Solid State Ionics, 2000Co-Authors: A Endo, Hiroshi Fukunaga, Chingju Wen, Koichi YamadaAbstract:Abstract Dense La 0.6 Sr 0.4 CoO 3 (LSC) and La 0.81 Sr 0.09 MnO 3 (LSM) were prepared by laser ablation on samaria-doped ceria (SDC) and yttria-stabilized zirconia (YSZ) substrates, respectively. The interfacial conductivity of the dense LSM electrodes was independent of the oxygen partial pressure and inversely proportional to the thickness of the LSM film. On the other hand, the interfacial conductivity of the dense LSC electrode was proportional to the square root of the oxygen partial pressure, which indicates the sensitivity of the surface Reaction to the overpotential. To determine the origin of the overpotential, we constructed a surface-Reaction model. Good agreement was found between our model and experimental results.
-
Cathodic Reaction mechanism for dense sr doped lanthanum manganite electrodes
Solid State Ionics, 1996Co-Authors: Akira Endo, Manabu Ihara, Hiroshi Komiyama, Koichi YamadaAbstract:Abstract Dense La0.81Sr0.09MnO3 (LSM) electrode was prepared by a laser ablation method and electrochemical measurements were carried out. The electrode impedance was proportional to the film thickness and almost independent of the oxygen partial pressure. Steady-state polarization characteristics were measured and oxygen ionic conductivity of LSM as calculated using Hebb-Wagner polarization method. The slopes of log i − log a0 curves were calculated to be −1 2 . These results suggest that the Cathodic Reaction mechanism of the dense LSM electrode is quite different from that of porous electrode.
G T Burstein - One of the best experts on this subject based on the ideXlab platform.
-
some aspects of the role of inhibitors in the corrosion of copper in tap water as observed by cyclic voltammetry
Corrosion Science, 2016Co-Authors: G T Burstein, B B Rodriguez, G KawaleyAbstract:Abstract Cyclic voltammetric examination of the corrosion and inhibition of copper in hard and soft tap-waters in the presence of a commercial inhibitor containing benzotriazole (BTA) and triethanolamine (TEA), or its separate components, is presented. The anodic and Cathodic Reactions are both strongly inhibited, although the anodic Reaction more so. BTA is by far the dominant inhibiting component. The inhibitor forms a polymerized reactive adsorbed surface film. Inhibition of the Cathodic Reaction (oxygen reduction) is not due to electron resistivity of the inhibitor, but rather, by heavily reduced surface coverage of adsorbed oxygen over a wide range of oxygen reduction overpotential.
-
imaging metastable pits on austenitic stainless steel in situ at the open circuit corrosion potential
Electrochemistry Communications, 2004Co-Authors: Y Gonzalezgarcia, G T Burstein, S Gonzalez, R M SoutoAbstract:Abstract Images describing metastable pits on 304 stainless steel obtained in situ in chloride solution at the open-circuit corrosion potential are presented. These images were obtained by scanning electrochemical microscopy and represent the oxidation of Fe 2+ emanating from the metastable pits as the probe tip passes over them. Each anodic transient on the tip is succeeded by a transient in the Cathodic direction. We ascribe this to an indirect observation of the Cathodic Reaction. Reduction of oxygen as the Cathodic Reaction causes peroxide to be produced adjacent to the propagating pits. This reacts with Fe 2+ produced by the background passive current locally around the pit site. The microscope tip, set to detect Fe 2+ , detects the reduced background current as a transient negative wing immediately after the anodic wing associated with the pit itself. The signal represents a reduced anodic background current. This negative wing on the probe current is not detected when the metastable pits are generated under potentiostatic polarisation. It is shown that the lifetime of the detected pits is a maximum of a few seconds.
-
the Cathodic Reaction during repassivation of aluminium in open circuit
Corrosion Science, 1995Co-Authors: G T BursteinAbstract:Experiments have been carried out to investigate the role of Cathodic processes in the repassivation of aluminium in open circuit using the guillotined electrode. These measurements involve application of an electrochemical perturbation to the open-circuit potential. The results reveal that the rate of the Cathodic Reaction at constant potential is independent of the film thickness, but the open-circuit repassivation potential transient depends on the Cathodic reactant. The rate-control of these processes cannot be explained by electron tunnelling alone.
M A Quraishi - One of the best experts on this subject based on the ideXlab platform.
-
corrosion inhibition of n80 steel in 15 hcl by pyrazolone derivatives electrochemical surface and quantum chemical studies
RSC Advances, 2016Co-Authors: K R Ansari, M A Quraishi, Ambrish Singh, Sowmya Ramkumar, Ime B OboteAbstract:The corrosion protection of N80 steel in 15% HCl by two pyrazolone derivatives namely 2-(3-amino-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)(p-tolyl)methyl)malononitrile (PZ-1) and 2-((3-amino-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methyl)malononitrile (PZ-2) has been investigated by using gravimetric, electrochemical and quantum chemical studies. The observed results reveal that PZ-1 is a better inhibitor than PZ-2. Tafel polarization showed that PZs are mixed type inhibitors but dominantly affect the Cathodic Reaction. Both inhibitors were found to obey the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) images support the protection of the N80 steel in the presence of the PZs. Quantum chemical study reveals that both inhibitors have a tendency to get protonated and this result supports the experimental observations.
-
inhibitive effect of diethylcarbamazine on the corrosion of mild steel in hydrochloric acid
Corrosion Science, 2010Co-Authors: Ashish Kumar Singh, M A QuraishiAbstract:Abstract Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), weight loss measurements and atomic force microscopy techniques were used to investigate the inhibitory effect of diethylcarbamazine (DECM) on corrosion of mild steel in HCl solution. The inhibitor showed >90% inhibition efficiency at 5.01 × 10−4 M. Results obtained revealed that inhibition occurs through adsorption of inhibitor molecules on metal surface without modifying the mechanism of corrosion process. Potentiodynamic polarization studies suggested that it is a mixed type inhibitor, predominantly controls Cathodic Reaction. Activation parameters ( E a , Δ H and Δ S ) and thermodynamic parameters ( Δ G ads o , Δ H ads o and Δ S ads o ) were calculated to investigate mechanism of inhibition.
-
effect of cefazolin on the corrosion of mild steel in hcl solution
Corrosion Science, 2010Co-Authors: Ashish Kumar Singh, M A QuraishiAbstract:Abstract The adsorption and inhibition effect of Cefazolin on mild steel in 1.0 M HCl at 308–338 K was studied by weight loss, EIS, potentiodynamic polarization and atomic force microscopy techniques. The results showed that inhibition efficiency increased with inhibitor concentration. The adsorption of Cefazolin on mild steel surface obeys the Langmuir adsorption isotherm equation. Both thermodynamic (enthalpy of adsorption Δ H ads ∘ , entropy of adsorption Δ S ads ∘ and free energy of adsorption Δ G ads ∘ ) and kinetic parameters (activation energy Δ E a ∘ and pre-exponential factor A) were calculated and discussed. Polarization curves showed that Cefazolin acted as mixed-type inhibitor controls predominantly Cathodic Reaction.