scholarly journals Degradation Behaviors of Two Epoxy Coatings After Dry/Wet-Accelerated Fog Exposure of Different Solutions

2021 ◽  
Vol 8 ◽  
Author(s):  
Jibiao Zhang ◽  
Bo Zhu ◽  
Haoran Wang ◽  
Cheng Zhang ◽  
Weixiu Zeng ◽  
...  
Keyword(s):  
Electrochemical Noise ◽  
Electrochemical Impedance ◽  
Organic Coating ◽  
Deionized Water ◽  
Kelvin Probe ◽  
Mixed Salt ◽  
Epoxy Coatings ◽  
Degradation Behaviors ◽  
Pigmented Coatings ◽  
Deviation Method

Applying organic coating is an important and effective approach for the protection of metal from corrosion. Weathering degradation and under-film corrosion are the two major important factors that cause the failure of organic coatings. In this work, the degradation investigation of two epoxy coatings (clear and pigmented coatings) was carried out under the dry–wet circulation of three different water fog solutions (deionized water, 0.5 wt% NaCl, 0.05 wt% NaCl + 0.35 wt% (NH4)2SO4) in 35 days. The apparent performance (pull-off adhesion and surface potentials) and electrochemical features [electrochemical noise and electrochemical impedance spectroscopy (EIS)] of the coating samples were monitored after dry–wet fog exposure. In our three accelerating systems of the fog atmosphere, the time that the detectable defects appeared on the surface of coating samples was far ahead in the mixed salt solution than that in the deionized water or 0.5 wt% NaCl solution. For a defective or damaged coating surface, the derived results by using the standard deviation method (SDM) or Fourier power spectrum (FPS) were rather higher than those obtained from EIS as a whole, while for the same coating, the degradation trend with time derived from EIS, SDM, FPS, and scanning Kelvin probe was consistent with each other.

Modified of the Epoxy Coatings by Polyaniline

2019 ◽  
Vol 816 ◽  
pp. 271-278 ◽  
Author(s):  
Vladimir G. Kurbatov ◽  
T.A. Pugacheva
Keyword(s):  
Epoxy Polymer ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Organic Coating ◽  
Epoxy Coatings ◽  
Actual Problem ◽  
Epoxy Primer ◽  
Polarization Studies ◽  
Metal Protection ◽  
Anticorrosion Properties

An actual problem is searching of new pathways of increase of anticorrosion properties of an organic coating. In the field of practice and the theory of metal protection from corrosion recently there were novel trends. One of them – making and examination of the conducting polymers inhibiting corrosion of many metals. Influence of the amine hardener modified by polyaniline (PANi) on anticorrosion properties of epoxy coatings in various corrosion-active mediums was studied. The polarization studies have shown that the introduction of PANI in the epoxy polymer coating reduces the corrosion current density. Using electrochemical impedance spectroscopy has established that coatings containing of PANI, are less permeable due to its hydrophobic. It was showed, that PANi it can be used for increase of anticorrosion properties of manufacturing epoxy primer.

EIS study of the corrosion behavior of an organic coating applied on Algerian oil tanker

2020 ◽  
Vol 117 (6) ◽  
pp. 610
Author(s):  
Nadia Hammouda ◽  
Kamel Belmokre
Keyword(s):  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Paint Film ◽  
Organic Coating ◽  
Diffusion Resistance ◽  
Double Layer Capacitance ◽  
Carbon Steel Surface ◽  
Chloride Environment ◽  
Oil Tanker ◽  
Epoxy Paint

Organic coatings are widely employed in the corrosion protection of most metal surfaces, particularly steel. They provide a barrier against corrosive species present in the environment, due to their high resistance to oxygen, water and ions transport. This study focuses on the evaluation of corrosion protection performance of epoxy paint on the carbon steel surface in chloride environment (3% NaCl) by Electrochemical Impedance Spectroscopy (EIS). The electrochemical behavior of painted surface was estimated by EIS parameters that contained paint film resistance, paint film capacitance and double layer capacitance. On the basis of calculation using EIS spectrums it was observed that pore resistance (Rpore) decreased with the appearance of doubled layer capacitance (Cdl) due to the electrolyte penetration through the film. This was further confirmed by the decrease of diffusion resistance (Rd) which was also the indicator of the deterioration of paint film protectiveness. Microscopic analyses have shown that oxidation dominates the corroded surfaces.

scholarly journals Zn-Co-CeO2 vs. Zn-Co Coatings: Effect of CeO2 Sol in the Enhancement of the Corrosion Performance of Electrodeposited Composite Coatings

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 704
Author(s):  
Marija Riđošić ◽  
Nebojša D. Nikolić ◽  
Asier Salicio-Paz ◽  
Eva García-Lecina ◽  
Ljiljana S. Živković ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Healing Rate ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Self Healing ◽  
Kelvin Probe ◽  
Artificial Defect ◽  
Volta Potential ◽  
Superior Corrosion Resistance ◽  
The Stability

Electrodeposition and characterization of novel ceria-doped Zn-Co composite coatings was the main goal of this research. Electrodeposited composite coatings were compared to pure Zn-Co coatings obtained under the same conditions. The effect of two ceria sources, powder and home-made sol, on the morphology and corrosion resistance of the composite coatings was determined. During the electrodeposition process the plating solution was successfully agitated in an ultrasound bath. The source of the particles was found to influence the stability and dispersity of plating solutions. The application of ceria sol resulted in an increase of the ceria content in the resulting coating and favored the refinement from cauliflower-like morphology (Zn-Co) to uniform and compact coral-like structure (Zn-Co-CeO2 sol). The corrosion resistance of the composite coatings was enhanced compared to bare Zn-Co as evidenced by electrochemical impedance spectroscopy and scanning Kelvin probe results. Zn-Co doped with ceria particles originating from ceria sol exhibited superior corrosion resistance compared to Zn-Co-CeO2 (powder) coatings. The self-healing rate of artificial defect was calculated based on measured Volta potential difference for which Zn-Co-CeO2 (sol) coatings exhibited a self-healing rate of 73.28% in a chloride-rich environment.

scholarly journals Using Graphene-Based Composite Materials to Boost Anti-Corrosion and Infrared-Stealth Performance of Epoxy Coatings

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1603
Author(s):  
Meng-Jey Youh ◽  
Yu-Ren Huang ◽  
Cheng-Hsiung Peng ◽  
Ming-Hsien Lin ◽  
Ting-Yu Chen ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Graphene Nanosheets ◽  
Salt Spray ◽  
Corrosion Current ◽  
Filler Concentration ◽  
Epoxy Coatings ◽  
Corrosion Properties ◽  
Water Contact ◽  
Different Temperatures ◽  
Thermal Signature

Corrosion prevention and infrared (IR) stealth are conflicting goals. While graphene nanosheets (GN) provide an excellent physical barrier against corrosive agent diffusion, thus lowering the permeability of anti-corrosion coatings, they have the side-effect of decreasing IR stealth. In this work, the anti-corrosion properties of 100-μm-thick composite epoxy coatings with various concentrations (0.01–1 wt.%) of GN fillers thermally reduced at different temperatures (300 °C, 700 °C, 1100 °C) are first compared. The performance was characterized by potentiodynamic polarization scanning, electrochemical impedance spectroscopy, water contact angle and salt spray tests. The corrosion resistance for coatings was found to be optimum at a very low filler concentration (0.05 wt.%). The corrosion current density was 4.57 × 10−11 A/cm2 for GN reduced at 1100 °C, showing no degradation after 500 h of salt-spray testing: a significant improvement over the anti-corrosion behavior of epoxy coatings. Further, to suppress the high IR thermal signature of GN and epoxy, Al was added to the optimized composite at different concentrations. The increased IR emissivity due to GN was not only eliminated but was in fact reduced relative to the pure epoxy. These optimized coatings of Al-GN-epoxy not only exhibited greatly reduced IR emissivity but also showed no sign of corrosion after 500 h of salt spray test.

Transient Analysis and Simulation of Pitting Corrosion for the Estimation of Noise Resistance

CORROSION ◽  
2000 ◽  
Vol 56 (9) ◽  
pp. 928-934
Author(s):  
G. Miramontes de León ◽  
D. C. Farden ◽  
D. E. Tallman
Keyword(s):  
Computer Simulation ◽  
Pitting Corrosion ◽  
Transient Analysis ◽  
Electrochemical Noise ◽  
Electrochemical Impedance ◽  
Transient Behavior ◽  
Noise Resistance ◽  
New Approach ◽  
Noise Data ◽  
Current Transients

Abstract A new approach for the measurement of noise resistance based on the transient behavior of pitting corrosion is presented. Potential noise and current transients have been recognized as a characteristic behavior of pitting corrosion. This new approach uses the transient information present during corrosion as a way to estimate the noise resistance of coated metals directly. Computer simulation and analytical results are presented, indicating that the new technique can be applied to the problem of noise resistance estimation. This new approach was applied to experimental electrochemical noise data obtained with commercial electrochemical impedance spectroscopy (EIS)/electrochemcial noise measurement (ENM) equipment.

scholarly journals In-Situ Evaluation of the Protectivity of Coatings Applied to Metal Cultural Artefacts Using Non-Destructive Electrochemical Measurements

2021 ◽  
Vol 2 (1) ◽  
pp. 120-132
Author(s):  
Douglas J. Mills ◽  
Katarzyna Schaefer ◽  
Tomasz Wityk
Keyword(s):  
Baltic Sea ◽  
Electrochemical Noise ◽  
Organic Coating ◽  
Noise Measurement ◽  
The Baltic Sea ◽  
Coating Type ◽  
The Baltic ◽  
Non Destructive ◽  
Electrolytic Resistance

Electrochemical Noise Measurement (ENM) and DC electrolytic resistance measurement (ERM) can be used to assess the level of protectiveness provided by an organic coating (paint or varnish) to the underlying metal. These techniques also have applicability to the thinner, transparent type of coatings used to protect archaeological artefacts. Two studies are presented here demonstrating how ERM and ENM techniques can be applied in artefact preservation. The similarity of the techniques, both of which are a measure of resistance, means results can be considered to be analogous. The first study investigated the use of ERM to determine the protection levels provided by typical coatings in order to develop a database of coating type and application for objects, for specific environments. The second study used ENM to evaluate coatings which had been applied to historic artefacts recovered from shipwrecks in the Baltic Sea and displayed inside the museum or kept in the museum store area. The studies showed the usefulness of both techniques for determining the level of protection of a coating and how a better performing coating can be specified if a pre-existing coating on an artefact has been found to be unsuitable.

scholarly journals Preparation and Properties of Self-Healing and Self-Lubricating Epoxy Coatings with Polyurethane Microcapsules Containing Bifunctional Linseed Oil

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1578 ◽  
Author(s):  
Haijuan Yang ◽  
Qiufeng Mo ◽  
Weizhou Li ◽  
Fengmei Gu
Keyword(s):  
Interfacial Polymerization ◽  
Electrochemical Impedance ◽  
Linseed Oil ◽  
Salt Spray ◽  
Average Diameter ◽  
Organic Coating ◽  
Epoxy Coating ◽  
The Self ◽  
Self Healing ◽  
Pure Epoxy

An organic coating is commonly used to protect metal from corrosion, but it is prone to failure due to microcracks generated by internal stress and external mechanical action. The self-healing and self-lubricating achieved in the coating is novel, which allows an extension of life by providing resistance to damage and repair after damage. In this study, a new approach to microencapsulating bifunctional linseed oil with polyurethane shell by interfacial polymerization. Moreover, the self-healing and self-lubricating coatings with different concentrations of microcapsules were developed. The well-dispersed microcapsules showed a regular spherical morphology with an average diameter of ~64.9 μm and a core content of 74.0 wt.%. The results of the salt spray test demonstrated that coatings containing microcapsules still possess anticorrosion, which is improved with the increase of microcapsules content, after being scratched. The results of electrochemical impedance spectroscopy showed a |Z|f=0.01Hz value of 104 Ω·cm2 for pure epoxy coating after being immersed for 3 days, whereas the coating with 20 wt.% microcapsules was the highest, 1010 Ω·cm2. The results of friction wear showed that the tribological performance of the coating was enhanced greatly as microcapsule concentration reached 10 wt.% or more, which showed a 86.8% or more reduction in the friction coefficient compared to the pure epoxy coating. These results indicated that the coatings containing microcapsules exhibited excellent self-healing and self-lubricating properties, which are positively correlated with microcapsules content.

scholarly journals Corrosion Behavior of Al in Ethanol–Gasoline Blends

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5544
Author(s):  
Alfredo Brito-Franco ◽  
Jorge Uruchurtu ◽  
Isai Rosales-Cadena ◽  
Roy Lopez-Sesenes ◽  
Sergio Alonso Serna-Barquera ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Sugar Cane ◽  
Electrochemical Noise ◽  
Electrochemical Impedance ◽  
Pure Aluminum ◽  
Electrochemical Techniques ◽  
Intermediate Compound ◽  
Corrosion Process ◽  
Corrosion Rates ◽  
Adsorption Desorption

The corrosion behavior of pure aluminum (Al) in 20 v/v% ethanol–gasoline blends has been studied using electrochemical techniques. Ethanol was obtained from different fruits including sugar cane, oranges, apples, or mangos, whereas other techniques included lineal polarization resistance, electrochemical noise, and electrochemical impedance spectroscopy for 90 days. Results have shown that corrosion rates for Al in all the blends were higher than that obtained in gasoline. In addition, the highest corrosion rate was obtained in the blend containing ethanol obtained from sugar cane. The corrosion process was under charge transfer control in all blends; however, for some exposure times, it was under the adsorption/desorption control of an intermediate compound. Al was susceptible to a localized, plotting type of corrosion in all blends, but they were bigger in size and in number in the blend containing ethanol obtained from sugar cane.

scholarly journals Electrochemical Impedance Spectroscopy Evaluation of Organic Coating on Mild Steel

2018 ◽  
Vol 7 (3.11) ◽  
pp. 30
Author(s):  
Zailelah Zainoldin ◽  
Hadariah Bahron ◽  
Mohamad Kamal Harun ◽  
Syaidah Athirah Dzolin
Keyword(s):  
Mild Steel ◽  
Steel Surface ◽  
Electrochemical Impedance ◽  
Organic Coating ◽  
Electrical Equivalent Circuit ◽  
Mild Steel Surface ◽  
Electro Oxidation ◽  
Nyquist Plots ◽  
Eis Measurements ◽  
Voltammetric Technique

Electro-oxidation of 4-hydroxybenzalaniline in alkaline solution on mild steel surface was successfully carried out using cyclic voltammetric technique. Results demonstrated that brownish colour appeared on the mild steel surface after the cycle of voltammetric study. The presence of film was confirmed by the EIS measurement whereas the Nyquist plots obtained from EIS measurements were fitted with suitable electrical equivalent circuit. The coated mild steel exhibit better polarization resistance than uncoated mild steel.  

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