Electrochemical Behaviors of Die-Cast Mg-4Al-0.4Mn-Xpr (x=0, 1, 4) Alloys in NaCl Solution

2013 ◽  
Vol 690-693 ◽  
pp. 82-88
Author(s):  
Xiao Dong Niu ◽  
Wei Sun ◽  
Xin Qiu ◽  
Jian Meng ◽  
Jian An
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Nacl Solution ◽  
Electrochemical Behaviors ◽  
Β Phase ◽  
Die Cast ◽  
Corrosion Behaviors ◽  
Potential Test

The microstructures and electrochemical corrosion behaviors of die-cast Mg-4Al-0.4Mn-xPr (x=0, 1, 4 wt.%) alloys have been investigated. Electrochemical behaviors of all alloys are described by open circuit potential test, potentiodynamic polarization test and electrochemical impedance spectroscope in 3.5 wt.% NaCl solution. The results show that the α-Mg grain is refined and the continuous net β phase appears gradually with increasing the content of Pr in the Mg-4Al-0.4Mn alloys. Moreover, the β phase plays a role of galvanic cathode in AM40 alloy and corrosion barrier in Pr-containing alloys, respectively. Electrochemical measurements show that Pr can improve corrosion resistance of Mg-4Al-0.4Mn alloy in the 3.5 wt.% NaCl solution, and corrosion rate decreases with increasing Pr content.

Electrochemical corrosion behavior of HVOF sprayed WC–12Co coating on H13 hot work mould steel

2019 ◽  
Vol 66 (6) ◽  
pp. 827-834
Author(s):  
Kong Weicheng ◽  
Shen Hui ◽  
Gao Jiaxu ◽  
Wu Jie ◽  
Lu Yuling
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Curvature Radius ◽  
Nacl Solution ◽  
Content Type ◽  
Capacitance Curve ◽  
Electrochemical Corrosion Behavior ◽  
Corrosion Behaviors

Purpose This study aims to investigate the electrochemical corrosion performance of high velocity oxygen fuel (HVOF) sprayed WC–12Co coating in 3.5 Wt.% NaCl solution, which provided a guiding significance on the corrosion resistance of H13 hot work mould steel. Design/methodology/approach A WC–12Co coating was fabricated on H13 hot work mould steel using a HVOF, and the electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution was measured using open circuit potential (OCP), potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS) tests. Findings The OCP and PPC of WC–12Co coating positively shift than those of substrate, its corrosion tendency and corrosion rate decrease to enhance its corrosion resistance. The curvature radius of capacitance curve on the WC–12Co coating is larger than that on the substrate, and the impedance and polarization resistance of WC–12Co coating increase faster than those of substrate, which reduces the corrosion process. Originality/value The electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution is first measured using OCP, PPC and EIS tests, which improve the electrochemical corrosion resistance of H13 hot work mould steel.

Study on Corrosion Behaviors of Epoxy Aluminum Coating Immersed in 3.5%NaCl Solution

2014 ◽  
Vol 912-914 ◽  
pp. 338-341 ◽  
Author(s):  
Rui Yan ◽  
Ting Liang ◽  
Hong Chun Ren ◽  
Jin Gu ◽  
Zhuang Zhou Ji
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Osmotic Pressure ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Aluminum Coating ◽  
Nacl Solution ◽  
Metal Interface ◽  
Electrochemical Corrosion Behavior ◽  
Corrosion Behaviors

Electrochemical corrosion behavior of epoxy aluminum coating immersed in 3.5%NaCl solution was investigated using electrochemical impedance spectroscopy (EIS). SEM was also used to analyze the surface images of coating, and the failure mechanism was discussed as well. The experimental results showed that corrosive species can penetrate into coatings and reach the coating/substrate interface promptly, causing the decrease of electro-resistance and the beginning of electrochemical corrosion at the coatings/metal interface. The coating was compact and continuous at beginning, while the blisters and cavities appeared after corrosion, which were formed osmotic pressure created by corrosion species penetration.

Electrochemical Corrosion of As-Cast and Annealed Zr48Cu36Al8Ag8 BMG in 0.1 M NaCl Solution

2016 ◽  
Vol 863 ◽  
pp. 65-69
Author(s):  
Jing Chie Lin ◽  
Mao Chia Huang ◽  
Ongki B. Anggriawan ◽  
Jason Shian Ching Jang ◽  
M. Agus Choiron
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Crystal Defects ◽  
Crystal Phase ◽  
Annealing Duration ◽  
Corrosion Mechanism ◽  
Nacl Solution ◽  
Cast Specimen

Electrochemical corrosion of as-cast and annealed zirconium-based bulk metallic glass (BMG) Zr48Cu36Al8Ag8 in 0.1 M NaCl solution was investigated in this work. The as-cast specimen, in complete amorphous form, contained null percent of crystal phase (denoted as 0C); however, the annealed ones contained 11, 25, 50, 75 and 100 % crystal phase (denoted as 11C, 25C, 50C, 75C and 100C, respectively) determined by the annealing duration of 0C specimen at 471 °C. Through monitoring of open circuit potential (OCP), measurements of direct-current polarization resistance (PR), Tafel plot (TP), cyclic anodic potentiodynamic polarization (CAPD), and electrochemical impedance spectroscopy (EIS), we found that the corrosion behavior of the Zr48Cu36Al8Ag8 was detremined by the the crystal phase present in the specemns dominated by the annealing durations. The corrosion resistance decreased in the order: 25C > 11C > 0C > 50C > 75C > 100C. This result revealed that the corrosion resistance inclined to be better and reached a mxmium with increasing the percentgae of the crystal phase from 0 to 25%; however, it decreased with further increasing the crystal phase over 25%. A corrosion mechanism is proposed to rationalize the sequence of corrosion resistance. According to the mechanism, the remained free volume and residual strain energy are responsible for the specimens containing crystal phase less than 25% (i.e., 0C, 11C and 25C); whereas crystal defects such as grain boundaries governed the corrosion of those containing crystal phase more than 25 % (i.e., 50C, 75C and 100C).

scholarly journals Preparation of Coating on the Titanium Surface by Micro-Arc Oxidation to Improve Corrosion Resistance

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 230 ◽  
Author(s):  
Yulong Hu ◽  
Zhiqiao Wang ◽  
Jianyang Ai ◽  
Shichao Bu ◽  
Hongwei Liu
Keyword(s):  
Corrosion Resistance ◽  
Titanium Surface ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coating Structure ◽  
Lower Porosity ◽  
Micro Arc Oxidation ◽  
Corrosion Behaviors ◽  
Different Thickness

In this paper, two kinds of micro-arc oxidation (MAO) coatings on TA2 with different thickness were prepared by controlled oxidation time and then were characterized for their composition, crystalline structure, and surface morphology. The effect of MAO treatment on electrochemical corrosion behaviors of TA2 in 3.5% NaCl solution were studied by the electrochemical measurements including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. The results indicate that the electrochemical behavior of MAO coating is related to the coating structure. OCP can be used to evaluate the porosity of MAO coating. More positive OCP indicates coating with lower porosity and larger resistance obtained from EIS. The MAO treatment can significantly enhance the corrosion resistance of TA2, but the thickness increase of MAO coating could not further improve the corrosion resistance. In addition, because of the increase in effective surface area, the MAO treatment may enhance the cathode action of TA2 when the galvanic cell is composed of TA2 and other more negative metal, which in turn promotes the corrosion of negative metal.

Application of EIS and SEM to Study the Corrosion Behaviors of Organic Coatings/Substrate System

2008 ◽  
Vol 373-374 ◽  
pp. 556-559 ◽  
Author(s):  
Rui Yan ◽  
Hang Wu ◽  
S.K. Yu ◽  
Shi Ning Ma ◽  
Bin Shi Xu
Keyword(s):  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Electrochemical Corrosion ◽  
Metal Substrate ◽  
Open Circuit ◽  
Free Corrosion Potential ◽  
Cross Linkage ◽  
Sem Micrograph ◽  
Corrosion Behaviors

Electrochemical corrosion behaviors of two common-used ship coatings——epoxy aluminum coating, chloride rubber iron red coating and their composite coatings immersed in 3.5%NaCl solution were investigated using electrochemical impedance spectroscopy combined with open circuit potential measurements and SEM micrograph analysis. Potential-time result indicates that the free corrosion potential of these three coatings with immersion time are more positive than that of metal substrate, which can serve as barrier layer to protect metal substrate from corrosion. During the course of immersion, increasingly negative shift potentials with time reveal the growth of electrochemical area of anode and corrosion takes place continuously. EIS shows that corrosive species can penetrate into coatings and reach the coating/substrate interface promptly, causing the decrease of its shielding role and the beginning of electrochemical corrosion. SEM micrographs suggest that coatings were compact and continuous compared with obviously coarse and loose after corrosion, indicating the penetration of corrosive species destroys cross linkage of coatings. Composite coatings present better protection performance, displaying the effect of “1+1>2” remarkably.

Interaction between Sodium Molybdate and FSWed Wled of 5083 Effected by Time

2013 ◽  
Vol 699 ◽  
pp. 645-649
Author(s):  
Chang Bin Shen
Keyword(s):  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Sodium Molybdate ◽  
Impedance Spectra ◽  
Electrochemical Impedance Spectra ◽  
Friction Stir ◽  
Base Materials ◽  
Corrosion Behaviors ◽  
5083 Aluminum Alloy

Similar welds composed of 5083 were produced by friction stir welding. In the solution of 0.2 M NaHSO3 and 0.6 M NaCl, with the addition of a given concentration sodium molybdate as the inhibitor, the electrochemical corrosion behaviors of the friction stir welds (FSW) and 5083 were comparatively investigated by potentiodynamic polarization curve tests and electrochemical impedance spectra (EIS) at the ambient temperature for different test periods. The results indicated that : with the extension of period, the inhibition efficiencies (IE) for both the weld and 5083 base materials enhanced, at the same period, the inhibition efficiency (IE) for the weld was beyond that for 5083 base materials, sodium molybdate may be thought of as an effective inhibitor for 5083 aluminum alloy, the interaction between inhibitor and weld is stronger than that between inhibitor and base materials.

Application of Electrochemical Techniques to Characterization of the Corrosion Behaviors of GW63 Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 571-574
Author(s):  
Xing Wu Guo ◽  
Jian Wei Chang ◽  
Shang Ming He ◽  
Peng Huai Fu ◽  
Wen Jiang Ding
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Time Curve ◽  
Completely Monotonic ◽  
Treatment Conditions ◽  
Impedance Variation ◽  
Corrosion Behaviors

The corrosion behavior of GW63 (Mg-6wt.%Gd-3wt.%Y-0.4wt.%Zr) alloys in 5% NaCl aqueous solution has been investigated by PARSTAT 2273 instrument. The Open Circuit Potential (ECORR) vs. time curve, cyclic polarization (Pitting Scans) curve and Electrochemical Impedance Spectroscopy (EIS) was measured for the GW63 alloys in as-cast and T6 heat treatment conditions. The EIS results indicated that the tendency of impedance variation for as-cast condition was monotonic decreasing, however, the tendency of variation for T6 condition was not completely monotonic but the total tendency was decreasing. The values of impedance of GW63 alloy at 0.1 Hz are about 103 ohm-cm2 for as-cast and T6 condition.

Corrosion Behavior of Al-Si-Cr-Cu Bearing Low Carbon Steel in A Cyclic Dry/Wet Laboratory Test

2009 ◽  
Vol 79-82 ◽  
pp. 1017-1020 ◽  
Author(s):  
Hui Shu Zhang ◽  
Dong Ping Zhan ◽  
Song Lian Bai ◽  
Zhou Hua Jiang
Keyword(s):  
Carbon Steel ◽  
Electrochemical Impedance ◽  
Low Carbon Steel ◽  
Optical Microscope ◽  
Low Carbon ◽  
Rust Layer ◽  
Electrochemical Behaviors ◽  
Corrosion Rates ◽  
The Matrix ◽  
Corrosion Behaviors

The corrosion behaviors of Al-Si-Cr-Cu bearing low carbon steel and a reference steel Q235 were tested in a cyclic dry/wet environment containing 0.01mol/L NaHSO3 in laboratory. Rust layers were observed by optical microscope (OM), scanning electron microscopy (SEM) and XRD. The electrochemical behaviors of the steels were studied on the polarization curves and electrochemical impedance spectroscopy (EIS). The results indicate that after 120h corrosion test, the annual corrosion rates of the designed steels reduce 42 % than Q235 at least. The corrosion products are generally iron oxyhydroxides and oxides such as FeOOH, γ-FeOOH, α-FeOOH, γ-Fe2O3, Fe3O4. The α-FeOOH possesses good stabilization mainly exits and can improve the corrosion resistance. There are the enrichments of Cu, Cr, Si and Al in the rust layer close to the matrix, which make the rust layer be more compact and protected. The corrosion currents of the two designed steels are lower than that of Q235, the corrosion potentials are higher than that of Q235 after Tafel fitting. The rust layer impedances of the designed steels are higher than that of Q235.

scholarly journals Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1325 ◽  
Author(s):  
Jian-Bao Wang ◽  
Guang-Chun Xiao ◽  
Wei Zhao ◽  
Bing-Rong Zhang ◽  
Wei-Feng Rao
Keyword(s):  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coarse Grained ◽  
Granular Bainite ◽  
X80 Pipeline Steel

The microstructure and corrosion resistance in H2S environments for various zones of X80 pipeline steel submerged arc welded joints were studied. The main microstructures in the base metal (BM), welded metal (WM), coarse-grained heat-affected zone (CGHAZ), and fine-grained heat-affected zone (FGHAZ) were mainly polygonal ferrite and granular bainite; acicular ferrite with fine grains; granular bainite, ferrite, and martensite/austenite constituents, respectively. The corrosion behavior differences resulted from the microstructure gradients. The results of the micro-morphologies of the corrosion product films and the electrochemical corrosion characteristics in H2S environments, including open circuit potential and electrochemical impedance spectroscopy, showed that the order of corrosion resistance was FGHAZ > BM > WM > CGHAZ.

Sign in / Sign up

Export Citation Format

Share Document