scholarly journals INFLUENCE OF A PREFABRICATED-CROWN ROLLING PROCESS ON THE CORROSION BEHAVIOUR OF AZ31 MAGNESIUM ALLOY

2021 ◽  
Vol 55 (4) ◽  
Author(s):  
Zhiquan Huang ◽  
Jinchao Zou ◽  
Junpeng Wang ◽  
Yanjie Pei ◽  
Renyao Huang ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Plate Thickness ◽  
Az31 Alloy ◽  
Rolling Process ◽  
Charge Transfer Resistance ◽  
Az31 Magnesium Alloy ◽  
Transfer Resistance

The present study aims to investigate the effect of a prefabricated-crown rolling process on the corrosion characteristic of the AZ31 magnesium alloy. Specimens made of the AZ31 alloy were rolled under various crown conditions, and their microstructure evolution and corrosion behavior were analyzed. The corrosion behavior was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion-current density of the AZ31 alloy with a side pressure of 37.5 % of the plate thickness of the precast convexity decreased from 3.79 × 10–6 A/cm2 to 1.80 × 10–6 A/cm2, and the difference between the edge and the middle of the AZ31 alloy was shortened from 2.05 × 10–6 A/cm2 to 1.14 × 10–6 A/cm2. The charge-transfer resistance also increased from 507.1 Ω·cm2 to 581.2 Ω·cm2. The improvement in the corrosion resistance is a result of the more stable corrosion products and microstructure refinement formed after the prefabricated-crown rolling process.

scholarly journals Effect of Cross Rolling on the Corrosion Resistance of AZ31 Magnesium Alloy

2020 ◽  
Vol 71 (8) ◽  
pp. 176-182
Author(s):  
Zhiquan Huang ◽  
Jinchao Zou ◽  
Guowei Yang ◽  
Yanchun Zhu ◽  
Hongyu Lai ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Az31 Magnesium Alloy ◽  
Constant Current ◽  
Transfer Resistance ◽  
Discharge Performance ◽  
Cross Rolling ◽  
Effective Contact

The effect of different rolling methods on the microstructure and corrosion behavior of AZ31 magnesium alloy in a 3.5% NaCl solution was studied via potentiodynamic polarization scanning, constant current discharge and electrochemical impedance spectroscopy. Results show that the corrosion current densities of cross rolling and unidirectional rolling are 8.60�10-3 and 4.68�10-2 A/cm2, respectively. Their difference is 5.4fold, the charge transfer resistance of cross rolling is large, the corrosion of one-way rolling is more serious than that of cross rolling, the discharge performance of cross rolling is more stable, and the anode polarization is small. After cross rolling, the grain size of the plate is relatively uniform and the corrosion products are non-adherent and less, so it is easy to fall off from its surface, which increases the effective contact between the electrolyte and the alloy surface and has more stable discharge performance.

Corrosion Behavior of 6000 Series Aluminum Alloys Produced by Conventional and Powder Extruded Process through Electrochemical Impedance Method

2010 ◽  
Vol 654-656 ◽  
pp. 1964-1967
Author(s):  
Satoshi Sunada ◽  
Norio Nunomura ◽  
Kazuhiko Majima
Keyword(s):  
Aluminum Alloys ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
The Other ◽  
Impedance Method ◽  
Ingot Metallurgy ◽  
Transfer Resistance ◽  
Maximum Charge ◽  
Cathodic Region

In this study, the electrochemical measurements such as the potentiodynamic polarization and the electrochemical impedance spectroscopy (EIS) tests were carried out in order to clarify the corrosion behavior of the aluminum alloys fabricated by powder extruded (P/E) process compared with those by ingot metallurgy (I/M) process, using 6000 system aluminum alloys. Two kinds of aluminum specimens; one is fabricated by the conventional I/M specimen and the other is fabricated by the P/E process, were used for the electrochemical experiment in the sulfuric acid solution with 0.5 kmol/m3 concentration. Both of I/M and P/E specimens showed the linear relationship between the electrochemical potential (E) and the common logarithm of current density (icorr) in the cathodic region where Tafel law was recognized irrespective of stirring of the test solution though the icorr was slightly increased by stirring for both specimens. On the other hand, in the anodic region, both of the two specimens indicated the almost the same icorr irrespective of stirring. These experimental results interpret that the corrosion is controlled by the chemical reaction. The EIS test indicated that the maximum charge transfer resistance (Rct) was observed at -0.55 V which is 0.11 V higher potential than the corrosion potential (Ecorr) for both of the two specimens.

scholarly journals Electrochemical properties and thermal stability of epoxy coatings electrodeposited on aluminium and modified aluminium surfaces

2001 ◽  
Vol 66 (11-12) ◽  
pp. 871-880 ◽  
Author(s):  
Vesna Miskovic-Stankovic ◽  
Zorica Lazarevic ◽  
Zorica Kacarevic-Popovic
Keyword(s):  
Thermal Stability ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Charge Transfer Resistance ◽  
Epoxy Coatings ◽  
Transfer Resistance ◽  
Protective Properties ◽  
Chemically Modified ◽  
Thermal Stability Of

The corrosion behaviour of epoxy coatings electrodeposited on aluminium, as well as on electrochemically and chemically modified aluminium were investigated during exposure to 3 % NaCl. Electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA) were used for the determination of the protective properties of epoxy coatings on aluminium, anodized aluminium, phosphatized and chromatized-phosphatized aluminium. The protective properties of epoxy coatings on anodized and chromatized-phosphatized aluminium are significantly improved with respect to the same epoxy coatings on aluminium and phosphatized aluminium: higher values of the pore resitance and charge-transfer resistance, lower values of the coating capacitance, double-layer capacitance and relative permittivity (from EIS) smaller amount of absorbed water inside the coating (From TGA). On the other hand, the lower values of the ipdt temperature indicate a lower thermal stability of the epoxy coatings on anodized and chromatized-phosphatized aluminium.

scholarly journals Electrochemical Corrosion Behavior of Ni-Fe-Co-P Alloy Coating Containing Nano-CeO2 Particles in NaCl Solution

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2614 ◽  
Author(s):  
Xiuqing Fu ◽  
Wenke Ma ◽  
Shuanglu Duan ◽  
Qingqing Wang ◽  
Jinran Lin
Keyword(s):  
Composite Coating ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Alloy Coating ◽  
Charge Transfer Resistance ◽  
Corrosion Mechanism ◽  
Nacl Solution ◽  
Transfer Resistance ◽  
Electrochemical Corrosion Behavior

In order to study the effect of nano-CeO2 particles doping on the electrochemical corrosion behavior of pure Ni-Fe-Co-P alloy coating, Ni-Fe-Co-P-CeO2 composite coating is prepared on the surface of 45 steel by scanning electrodeposition. The morphology, composition, and phase structure of the composite coating are analyzed by means of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion behavior of the coatings with different concentrations of nano-CeO2 particles in 50 g/L NaCl solution is studied by Tafel polarization curve and electrochemical impedance spectroscopy. The corrosion mechanism is discussed. The experimental results show that the obtained Ni-Fe-Co-P-CeO2 composite coating is amorphous, and the addition of nano-CeO2 particles increases the mass fraction of P. With the increase of the concentration of nano-CeO2 particles in the plating solution, the surface flatness of the coating increases. The surface of Ni-Fe-Co-P-1 g/L CeO2 composite coating is uniform and dense, and its self-corrosion potential is the most positive; the corrosion current and corrosion rate are the smallest, and the charge transfer resistance is the largest, showing the best corrosion resistance.

scholarly journals Initial Stages of AZ31B Magnesium Alloy Degradation in Ringer′s Solution: Interpretation of EIS, Mass Loss, Hydrogen Evolution Data and Scanning Electron Microscopy Observations

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 933 ◽  
Author(s):  
Lucien Veleva ◽  
Mareny Guadalupe Fernández-Olaya ◽  
Sebastián Feliu
Keyword(s):  
Magnesium Alloy ◽  
Hydrogen Evolution ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Uniform Corrosion ◽  
Transfer Resistance ◽  
Az31b Magnesium Alloy ◽  
Current Densities ◽  
Eis Measurements

The initial stages of corrosion of AZ31B magnesium alloy, immersed in Ringer′s solution at 37 °C body temperature for four days, have been evaluated by independent gravimetric and chemical methods and through electrochemical impedance spectroscopy (EIS) measurements. The corrosion current densities estimated by hydrogen evolution are in good agreement with the time-integrated reciprocal charge transfer resistance values estimated by EIS. The change in the inductive behavior has been correlated with difference in the chemical composition of corrosion layers. At the shorter immersion of 2 days, EDS analysis of cross section of the uniform corrosion layer detected Cl and Al elements, perhaps as formed aluminum oxychlorides salts.

Corrosion Resistance of Modified Silane Films Formed on AZ31 Magnesium Alloys

2011 ◽  
Vol 686 ◽  
pp. 21-25
Author(s):  
Xian Long Cao ◽  
Fu Sheng Pan ◽  
Hong Da Deng ◽  
Wei Cai
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Chloride Ions ◽  
Cerium Nitrate ◽  
Az31 Magnesium Alloy ◽  
Sodium Chloride Solutions

This present work investigated the corrosion behavior of AZ31 magnesium alloy substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane modified with cerium nitrate. The corrosion behavior of the pre-treated substrates in 0.005M sodium chloride solutions was assessed by potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS). The results showed that the silane pre-treatments improved the corrosion resistance of the AZ31 magnesium alloy substrates in the presence of chloride ions. Especially the addition of cerium nitrate played an important role in reducing the corrosion activity.

scholarly journals Electrochemical Characterization of Az31 Magnesium Alloy Treated by Ultrasonic Impact Peening (Uip)

2018 ◽  
Vol 20 (3) ◽  
pp. 24-29
Author(s):  
Daniel Kajanek ◽  
Branislav Hadzima ◽  
Filip Pastorek
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Az31 Alloy ◽  
Az31 Magnesium Alloy ◽  
Electrochemical Characteristics ◽  
Nyquist Plots ◽  
Eis Measurements ◽  
Testing Solution

Electrochemical characteristics of AZ31 magnesium alloy after impacting by ultrasonic impact peening (UIP) were measured in order to evaluate its effect on corrosion resistance of mentioned alloy. For this purpose, potentio-dynamic polarization (PD) tests and electrochemical impedance spectroscopy (EIS) of ground and impacted samples were performed in 0.1 M NaCl solution at the temperature of 22±2 °C after 5 minutes of potential stabilization. The obtained PD curves were analysed using the Tafel extrapolation method and data from EIS measurements in form of Nyquist plots were quantified by the equivalent circuit method. The results showed clearly that application of the UIP significantly deteriorated corrosion resistance of AZ31 alloy in the chosen testing solution.

The Corrosion Behavior of Cu-Ni-Si Alloy in Sea Water with Deep-Sea Bacteria

2014 ◽  
Vol 936 ◽  
pp. 1102-1105 ◽  
Author(s):  
Yuan Yuan Shen ◽  
Li Zhang ◽  
Li Hua Dong ◽  
Tao Liu ◽  
Qian Lei ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Deep Sea ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Microstructure Observation ◽  
Deep Sea Bacteria ◽  
Nutrient Rich Medium ◽  
Simulated Seawater

The corrosion behavior of Cu-Ni-Si alloy exposed to a nutrient-rich simulated seawater-based nutrient-rich medium in the presence of a deep-sea bacterial (Erythrobacter pelagi sp.nov) was investigated by metallographic microstructure observation, electrochemical impedance spectroscopy (EIS) measurement. It was demonstrated that the charge transfer resistance (Rct) and the resistance of oxide film (Rf) dramatically increased within 2 days then gradually decrease and becoming stable because of an patchy or blotchy biofilm formed on the surface of the alloy.

scholarly journals Corrosion behavior of wrought magnesium alloys AZ31 and AZ61 in Hank’s solution

2016 ◽  
Vol 60 (4) ◽  
pp. 101-106 ◽  
Author(s):  
J. Tkacz ◽  
K. Slouková ◽  
J. Minda ◽  
J. Drábiková ◽  
S. Fintová ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Az31 Magnesium Alloy ◽  
Az61 Magnesium Alloy ◽  
Potentiodynamic Curves ◽  
Hank’S Solution

Abstract Corrosion behavior of wrought magnesium alloys AZ31 and AZ61 was studied in Hank’s solution. Potentiodynamic curves measured after short-term of exposure showed higher corrosion resistance of AZ31 magnesium alloy in comparison with AZ61 magnesium alloy. On the contrary, long-term tests measured by electrochemical impedance spectroscopy showed higher corrosion resistance of AZ61 magnesium alloy in comparison with AZ31 magnesium alloy.

scholarly journals Corrosion and Electrochemical Impedance Spectroscopy of Thin TiALN and TiCN PVD Coatings for Protection of Ballast Water Screen Filters

2021 ◽  
Vol 58 (2) ◽  
pp. 64-78
Author(s):  
R. Kalnina ◽  
V. Priednieks ◽  
K. Lukins ◽  
A. Gasparjans ◽  
A. Rijkure
Keyword(s):  
Stainless Steel ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Surface Passivation ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Corrosion Behaviour ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Ticn Coating

Abstract The electrochemical impedance spectroscopy (EIS) and corrosion behaviour of physical vapour deposited (PVD) TiAlN and TiCN coatings of 50 µm mesh shaped AISI 316 stainless steel were estimated under simulated marine conditions (3.5 wt. % NaCl solution). The coatings were prepared by creating adhesive Cr-CrN interlayer with the thickness of about 0.3 µm. The obtained thicknesses of produced coatings were measured to be in a range between 2 and 3.5 µm. The presence of protective coatings leads to corrosion potential (Ecorr ) shifting to more positive values as compared to the bare stainless steel. This effect indicates higher protection efficiency of coated steel under marine conditions. The protective behaviour of produced coating leads to the decreased corrosion current density (jcorr ) by indicating up to 40-fold higher polarization resistance as compared to resistance of the naturally formed oxide layer over the stainless steel. The Nyquist and Bode plots were obtained with the help of EIS measurements by applying alternating potential amplitude of 10 mV on observed Ecorr . The obtained plots were fitted by appropriate equivalent circuits to calculate pore resistance, charge transfer resistance and capacitance. The present study reveals that pore resistance was the highest in the case of TiCN coating (Rpore =3.22 kΩ·cm2). The increase in duration of the immersion up to 24 h leads to change in the capacitive behaviour of the coatings caused by the penetration of the aqueous solution into pore system of TiCN coating with low wettability and surface passivation of reactive TiAlN coating. The presence of defects was confirmed by examining the obtained samples with the help of the scanning electron microscope.

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