scholarly journals Investigation of Protective Performance of a Mg-Rich Primer Containing Aluminum Tri-Polyphosphate on AZ91D Magnesium Alloy in Simulated Acid Rain

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 649 ◽  
Author(s):  
Xiangyu Lu ◽  
Sichen Sun ◽  
Qiqi Fan ◽  
Xiangjun Pei ◽  
Yuchao Dun ◽  
...  
Keyword(s):  
Acid Rain ◽  
Cathodic Protection ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Simulated Acid Rain ◽  
Protective Film ◽  
Az91d Alloy ◽  
Testing Environment ◽  
Protective Performance

Mg-rich primer (MRP) containing aluminum tri-polyphosphate functions via a galvanic mechanism to protect AZ91D alloy from corrosion in the 3 wt % NaCl solution. However, its protective performance can be strongly affected by the testing environment. Therefore, it is important to investigate the performance of the primer on magnesium alloys in an acid rain environment. In the present study, the protective performance of MRP with or without aluminum tri-polyphosphate was investigated via open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) in the simulated acid rain. Compared to the primer without aluminum tri-polyphosphate, the MRP containing aluminum tri-polyphosphate pigments exhibited better protective performance in the simulated acid rain condition. In the initial stage, the acidic condition prompted the aluminum tri-polyphosphate pigments to release phosphates and H+ to form magnesium phosphates on Mg particles, retarding their consumption rate. The Mg-rich primer with aluminum tri-polyphosphate can provide cathodic protection to AZ91D alloy for about 49 days in the simulated acid rain solution. Simultaneously, the corrosion products of Mg particles, magnesium oxides and phosphates, precipitated on the Mg particles and improved the stability of the primer. In addition, a protective film, consisting of magnesium oxides and phosphates, formed on the AZ91D substrate. Consequently, all these factors contributed to the long cathodic protection and improved corrosion resistance of MRP containing aluminum tri-polyphosphate in the simulated acid rain.

A Research on the Protective Performance of Green Organic Composite Coating on Vehicle Equipment

2013 ◽  
Vol 325-326 ◽  
pp. 79-82
Author(s):  
An Tao Xu ◽  
Bing Luo ◽  
Fan Zhang ◽  
Fu Jin ◽  
Yang Yang Liu
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Composite Coating ◽  
Research Method ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Simulation Research ◽  
Damage Level ◽  
Damage Simulation ◽  
Protective Performance

By adopting coating damage simulation research method with open circuit potential and electrochemical impedance spectroscopy, the influence of different damage levels of green organic composite coating to its protective performance has been studied. The research found that the variation of open circuit potential partly reflected the damage level of the coating. When K is less than or equal to 0.04, the coating still has favorable protective performance, while K is higher than 16, the protective performance of the coating is basically unavailable, but when K falls in between, the protective performance of the coating is fair good.

Comparative Study of the Corrosion Behavior of Low-Nickel AISI 202 and Conventional AISI 304 Stainless Steels in Citric Acid Using Electrochemical Techniques

2016 ◽  
Vol 835 ◽  
pp. 131-135 ◽  
Author(s):  
Francis Mulimbayan ◽  
Manolo G. Mena
Keyword(s):  
Stainless Steel ◽  
Citric Acid ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Corrosion Current ◽  
Open Circuit ◽  
Corrosion Mechanism ◽  
Protective Film ◽  
Aisi 304

Stainless steel (SS) is one of the most commonly used metallic food contact materials. It may be classified based on its microstructure whether ferritic, austenitic, martensitic, duplex or precipitation hardened. Austenitic SS, among mentioned grades, has the largest contribution to market due to its numerous industrial and domestic applications. In this study, the corrosion behavior of AISI 202 SS – a cheaper grade of stainless steel, in three different solution temperatures of citric acid was investigated using different electrochemical techniques such as open-circuit potential (OCP) measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results were compared to that obtained from conventional AISI 304 SS. OCP, polarization and impedance measurements agreed that AISI 202 SS has comparable resistance to that of AISI 304 SS in citric acid at ambient temperature and at 50 °C. At 70 °C, results of OCP measurements suggest that AISI 304 SS exhibited greater performance as indicated by more positive OCP values in the designated solution. EIS results indicate that the two alloys have identical corrosion resistance even at 70 °C as indicated by their comparable polarization resistance (Rp). The corrosion mechanism in both alloys is charge-transfer controlled as indicated by depressed semi-circular appearance of the generated Nyquist plots. The values of corrosion current densities (icorr) extracted from polarization curves indicate that the initial corrosion rates were higher in AISI 304 than AISI 202 SS suggesting that formation of more protective film may have occurred on the former alloy.

scholarly journals The Conjugated Phenylene Polymer-Modified Photoanodes for Quantum Dot-Sensitized Solar Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
So-Ra Lee ◽  
Da-Seul Kim ◽  
Seong-Ho Choi
Keyword(s):  
Solar Cells ◽  
Quantum Dot ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Electrochemical Polymerization ◽  
Contact Angles ◽  
Open Circuit ◽  
Cdse Qds ◽  
Ito Glass ◽  
Sensitized Solar Cells

Five types of conjugated phenylene polymer-modified photoanodes for quantum dot-sensitized solar cells (QDSSCs) were prepared by immobilization of CdSe QDs after electrochemical polymerization of functionalized phenyldiazonium salts onto ITO glass electrodes. The successful preparation of the conjugated phenylene polymer-modified photoanodes for QDSSCs was confirmed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, UV-visible spectroscopy, contact angles, and electrochemical impedance spectroscopy. The open-circuit voltage and fill factor in QDSSCs with the conjugated phenylene polymer with -COOH photoanodes were achieved at 0.52 V and 76.8%, respectively, and the energy conversion efficiency was improved to 2.73% using the conjugated phenylene polymer with -COOH photoanodes.

Use of Salvia hispanica as an eco-friendly corrosion inhibitor for bronze in acid rain

2017 ◽  
Vol 64 (6) ◽  
pp. 654-663 ◽  
Author(s):  
A.K. Larios-Galvez ◽  
J. Porcayo-Calderon ◽  
V.M. Salinas-Bravo ◽  
J.G. Chacon-Nava ◽  
Jose Gonzalo Gonzalez-Rodriguez ◽  
...  
Keyword(s):  
Acid Rain ◽  
Corrosion Inhibitor ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Simulated Acid Rain ◽  
Salvia Hispanica ◽  
Content Type ◽  
Green Corrosion Inhibitor ◽  
New Information ◽  
Practical Implications

Purpose The purpose of this research paper was to investigate the use of methanolic extract of Salvia hispanica (S. hispanica) as a green corrosion inhibitor for bronze in a simulated acid rain solution. Design/methodology/approach Extract of S. hispanica was used as a green corrosion inhibitor for bronze in simulated acid rain solution. Electrochemical techniques such as potentiodynamic polarization curves, electrochemical impedance spectroscopy and electrochemical noise were used. Parameters such as polarization, charge transfer and noise resistance (Rp, Rct and Rn, respectively) were calculated. Findings Results showed that the extract acts as a good, anodic type of inhibitor. The inhibitor efficiency increased with increasing its concentration up to 400 ppm, decreasing beyond this concentration. Efficiency also increased with an increase in the immersion time. The inhibition was due to the adsorption of components found in the S. hispanica extract following a Langmuir adsorption isotherm. Practical implications S. hispanica extract can be used as a corrosion inhibitor for bronze in acid rain solution. Originality/value This study provides new information on the inhibition features of S. hispanica under specific conditions. This eco-friendly inhibitor could find applications to protect bronze exposed to polluted urban atmospheres.

Corrosion resistance of ZrO2–Zr-coated biodegradable surgical magnesium alloy

2008 ◽  
Vol 23 (2) ◽  
pp. 312-319 ◽  
Author(s):  
Yunchang Xin ◽  
Chenglong Liu ◽  
Wenjun Zhang ◽  
Kaifu Huo ◽  
Guoyi Tang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Surface Hardness ◽  
Hardness Measurement ◽  
Open Circuit ◽  
Coated Sample ◽  
Az91 Magnesium Alloy ◽  
Coated Alloy

Magnesium alloys are potential biodegradable biomaterials in hard tissue implants. However, the fast degradation rate in the biological environment has hampered widespread applications. We propose to use a ZrO2 coating in conjunction with a Zr transition layer to improve the corrosion resistance of AZ91 magnesium alloy. X-ray photoelectron spectroscopy discloses that the coating is composed of ZrO2. The Vickers hardness measurement demonstrates that the surface hardness of the alloy is significantly enhanced. The electrochemical behavior of the coated sample is systematically evaluated by means of potentiodynamic polarization, open-circuit potential evolution, and electrochemical impedance spectroscopy. The electrochemical results indicate that the corrosion resistance of the coated alloy is enhanced significantly, and the electrode-controlled processes in a coated alloy–solution system are discussed.

Electrochemical Properties of Passive Film Formed on Supermartensitic Stainless Steel in a Chloride Medium

CORROSION ◽  
10.5006/3230 ◽  
2020 ◽  
Vol 76 (9) ◽  
pp. 884-890
Author(s):  
Renata B. Soares ◽  
Wagner R.C. Campos ◽  
Pedro L. Gastelois ◽  
Waldemar A.A. Macedo ◽  
Luís F.P. Dick ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Stainless Steel ◽  
Passive Film ◽  
Electrochemical Behavior ◽  
Photoelectron Spectroscopy ◽  
Oil And Gas ◽  
Electrochemical Impedance ◽  
Passive Layer ◽  
Open Circuit ◽  
Pitting Potential

The electrochemical behavior and the electronic properties of passive films formed on a super martensitic stainless steel (SMSS) used in oil and gas industries were investigated in aqueous 0.6 M and 2.1 M NaCl solutions with additions of sodium acetate and acetic acid (pH 4.5). Open-circuit potential transients, electrochemical impedance spectroscopy, cyclic voltammetry, and x-ray photoelectron spectroscopy were measured to characterize the passive film formed on SMSS. The electrochemical behavior of the steel in an aqueous solution of 0.6 M NaCl presented the highest pitting potential and the highest polarization resistance in relation to the NaCl/NaAc solution. The passive film of SMSS in an aqueous solution of NaCl presented a thickness of 18.40 nm, three times the thickness of the oxide film in NaCl/NaAc, and consisted of FeO, Cr2O3, MoO2, and spinels such as FeCr2O4 species that are a p-type semiconductor, but may also contain a small fraction of the Fe2O3 and MoO3 oxides. Additionally, it was shown that the passive layer after immersion in a saline solution also contains hydroxides such as FeOOH and Cr(OH)3.

Study of Electrochemical Behavior of the Transmission Tower Galvanized Layer in Simulated Acid Rain Solution

2013 ◽  
Vol 361-363 ◽  
pp. 1042-1045
Author(s):  
Hua Ling Deng ◽  
Qi Lei Sun
Keyword(s):  
Acid Rain ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Low Ph ◽  
Simulated Acid Rain ◽  
Corrosion Products ◽  
Precipitation Process ◽  
Layer Surface ◽  
Transmission Tower

Using electrochemical impedance spectroscopy (EIS), polarization curve and X-ray diffraction technique, electrochemical behavior of the transmission tower material Q460 galvanized layer was studied in simulated acid rain solution. The results show that: galvanized layers take place local corrosion in simulated acid rain solution, the corrosion products will fill the hole, and cover on galvanized layer surface, the generated white corrosion products mainly ZnSO4 ·H2O.The current generate in the process of corrosion, galvanized layer surface take place electrochemical corrosion. Galvanized layer solution at pH 2.4 and 3.8 of the simulated acid rain in the corrosion process is controlled by the charge transfer process, with the decrease of solution pH value, the corrosion rate increases. Zinc are more sensitive to H+ in the solution, in low pH value of solution, due to the strong hydrogen precipitation process, the zinc surface adsorption of hydrogen bubble around, its dissolution rate is higher than the surface of the other part of the zinc, namely in low pH value of acid rain solution, H+ by depolarization process not only directly accelerate the corrosion of zinc, can through the strong hydrogen evolution process at the same time accelerate the dissolution of zinc.

scholarly journals Corrosion Behavior of Extruded AM60-AlN Metal Matrix Nanocomposite and AM60 Alloy Exposed to Simulated Acid Rain Environment

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 990
Author(s):  
Luis Chávez ◽  
Lucien Veleva ◽  
Sebastián Feliu ◽  
Danai Giannopoulou ◽  
Hajo Dieringa
Keyword(s):  
Acid Rain ◽  
Metal Matrix ◽  
Electrochemical Impedance ◽  
Simulated Acid Rain ◽  
Localized Corrosion ◽  
Solution Ph ◽  
Transfer Resistance ◽  
Composite Surface ◽  
Metal Matrix Nanocomposite ◽  
Matrix Nanocomposite

The present work compared the initial stages of corrosion process development on the AM60-AlN metal matrix nanocomposite surface and on AM60, during their exposure for 30 days to simulated acid rain solution (SAR). The AlN nanoparticles were observed as “attached” to those of Mn-rich AlMn intermetallic particles, forming clusters. The introduction of 1.0 wt.% AlN (≈ 80 nm) in the AM60 alloy carried a slight grain refinement and favored the formation of a denser and more protective corrosion layer, suggested by the electrochemical impedance spectroscopy (EIS) values of higher charge transfer resistance (R2) and capacitance, characteristic of the double layer in the presence of corrosion products, and also suggested by Rn (EN) values, compared to those of the AM60 alloy. Thus, the concentration of the released Mg-ions from the composite surface was lower. Due to the increase in time of the SAR solution pH, Al de-alloying may occur, as well as Al(OH)3 formation, as confirmed by XPS analysis. Due to the presence of Cl-ions in SAR solution, localized corrosion was observed, suggested as fractional Gaussian noise of a stationary and persistent process in time, according to the PSD of the corrosion current fluctuations (EN).

scholarly journals Pentavalent Vanadium Species as Potential Corrosion Inhibitors of Al2Cu Intermetallic Phase in the Sulfuric(VI) Acid Solutions

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1946 ◽  
Author(s):  
Przemysław Kwolek ◽  
Barbara Kościelniak ◽  
Magdalena Wytrwal-Sarna
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Intermetallic Phase ◽  
Open Circuit ◽  
Acid Solutions ◽  
Scanning Calorimetry ◽  
Electrochemical Impedance Spectra ◽  
X Ray

The objective of this work was to test vanadium isopolyoxoanions as potential corrosion inhibitors of the intermetallic phase Al2Cu in sulfuric acid solutions at pH = 1.3 and 2.5. The intermetallic was melted in an electric arc furnace. Its phase composition was confirmed using X-ray diffraction, light microscopy, and differential scanning calorimetry. Then Al2Cu corrosion kinetics was studied. Chemical composition of the solution after corrosion was determined using inductively coupled plasma-optical emission spectroscopy. The surface of corroded specimens was analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy. Subsequent electrochemical studies involved determination of open-circuit potential, electrochemical impedance spectra, and polarization curves. It was found that the Al2Cu phase corrodes selectively and vanadium isopolyoxoanions increase this process both at pH = 1.3 and 2.5 with two exceptions. Corrosion inhibition was observed for 100 and 200 mM of Na3VO4 at pH 1.3, with inhibition efficiency 78% and 62% respectively, due to precipitation of V2O5.

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