scholarly journals Adhesion of epoxy cataphoretic coatings on Zn alloys

2007 ◽  
Vol 72 (12) ◽  
pp. 1383-1392 ◽  
Author(s):  
Jelena Bajat ◽  
Vesna Miskovic-Stankovic ◽  
Dragutin Drazic
Keyword(s):  
Electrochemical Impedance ◽  
Environmental Influence ◽  
Protective Coatings ◽  
Steel Substrate ◽  
Epoxy Coating ◽  
Nacl Solution ◽  
Corrosion Stability ◽  
Protective Properties ◽  
Protective System ◽  
Co Alloys

One of the most important factors in corrosion prevention by protective coatings is the loss of coating adhesion under environmental influence. In this work, the adhesion of epoxy cataphoretic coatings was examined on steel and steel modified by Zn-Fe and Zn-Co alloys. The dry and wet adhesions of epoxy primers were measured by the direct pull-off standardized procedure, as well as indirectly by the NMP test. The corrosion stability of the coated samples was investigated by electrochemical impedance spectroscopy. It was shown that under dry testing conditions all the samples exhibited very good adhesion. However, different trends of adhesion loss of different protective systems during exposure to a corrosive agent (3 % NaCl solution) were observed. The lowest adhesion values were obtained for epoxy coating on the steel substrate. The change in adhesion of the epoxy coating on steel modified by Zn-Co alloy during immersion in 3 % NaCl solution for 24 days was the smallest of all the investigated samples. Electrochemical impedance measurements in 3 % NaCl solution confirmed the good protective properties of this protective system, i.e., greater values of pore resistance were obtained.

Corrosion protective performance of epoxy-amino branched polydimethylsiloxane hybrid coatings on carbon steel

2015 ◽  
Vol 62 (5) ◽  
pp. 334-340
Author(s):  
Rami Mohammad Suleiman
Keyword(s):  
Carbon Steel ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Steel Substrate ◽  
Sol Gel ◽  
Hybrid Coatings ◽  
Nacl Solution ◽  
Cerium Ammonium Nitrate ◽  
Content Type ◽  
Steel Panels

Purpose – The purpose of this paper was to prepare a hybrid organic/inorganic coating with interesting barrier properties against the corrosion of plain carbon steel sheets in 3.5 per cent NaCl solution. The search for replacing chromates in protective coatings has led to the development of hybrid sol-gel anticorrosive coatings. Appropriate functionalization can dramatically enhance the chemical durability and mechanical strength of these coatings. Design/methodology/approach – To prepare the targeted coating, 1,2-epoxybutane (EB) was mixed with 2 to 4 per cent aminoethylaminopropyl-methylsiloxane dimethylsiloxane (APDMS) copolymer and 1,6-diaminohexane. The above coating (EBAC) has been further mixed with three different corrosion inhibitors “Moly-white® 101-ED, Heucophos Zapp® and cerium ammonium nitrate”, yielding the coatings EBAC-M, EBAC-Z and EBAC-Ce, respectively. The corrosion characteristics of all coatings on the steel panels immersed in 3.5 per cent NaCl solution were obtained using different electrochemical methods such as electrochemical impedance spectroscopic and Tafel polarization measurements. Findings – The newly prepared coatings showed interesting protection properties for protecting the steel substrate against corrosion in chloride-containing media. Originality/value – The results provide a good approach for the modification of polydimethylsiloxane coatings using a simple organic modifier.

Corrosion protective performance of epoxy-amino branched polydimethylsiloxane hybrid coatings on carbon steel

2014 ◽  
Vol 61 (6) ◽  
pp. 423-430 ◽  
Author(s):  
Rami Mohammad Suleiman
Keyword(s):  
Carbon Steel ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Steel Substrate ◽  
Sol Gel ◽  
Hybrid Coatings ◽  
Nacl Solution ◽  
Cerium Ammonium Nitrate ◽  
Content Type ◽  
Steel Panels

Purpose – The purpose of this work was to prepare a hybrid organic/inorganic coating with interesting barrier properties against the corrosion of plain carbon steel sheets in 3.5 per cent NaCl solution. The search for replacing chromates in protective coatings has led to the development of hybrid sol-gel anticorrosive coatings. Appropriate functionalization can dramatically enhance the chemical durability and mechanical strength of these coatings. Design/methodology/approach – To prepare the targeted coating, 1,2-epoxybutane (EB) was mixed with 2-4 per cent aminoethylaminopropyl-methylsiloxane dimethylsiloxane copolymer and 1,6-diaminohexane. The above coating (EBAC) was further mixed with three different corrosion inhibitors “Moly-white® 101-ED, Hfucophos Zapp®” and Cerium Ammonium Nitrate, yielding the coatings (EBAC-M), (EBAC-Z) and (EABC-Ce), respectively. The corrosion characteristics of all coatings on carbon steel panels immersed in 3.5 per cent NaCl solution were obtained using different electrochemical methods such as electrochemical impedance spectroscopic and Tafel polarization measurements. Findings – The newly prepared coatings showed interesting properties for protecting the steel substrate against corrosion in chloride containing media. Originality/value – The results provide a good approach for the modification of polydimethylsiloxane coatings using a simple organic modifier.

scholarly journals Influence of SiO2 Content and Exposure Periods on the Anticorrosion Behavior of Epoxy Nanocomposite Coatings

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 118 ◽  
Author(s):  
Alam ◽  
Samad ◽  
Sherif ◽  
Poulose ◽  
Mohammed ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Sio2 Nanoparticles ◽  
Epoxy Coating ◽  
Properties Of Coatings ◽  
Ft Ir ◽  
Eis Measurements ◽  
Coating Formulations

Epoxy coating formulations containing 1%, 3%, and 5% SiO2 nanoparticles were produced and applied on a mild steel substrate to achieve the objective of high performance corrosion resistance. The electrochemical impedance spectroscopy (EIS) technique was employed to measure the anticorrosive properties of coatings. The corrosion tests were performed by exposing the coated samples in a solution of 3.5% NaCl for different periods of time, varied from 1 h and up to 30 days. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses revealed the presence of nanoparticles in the final cured samples. Establishing the incorporation of the nanoparticles in the coating formulations was confirmed by employing both of XRD and FT-IR techniques. The FT-IR spectra have proved to be satisfactory indicating that there was a complete reaction between the epoxy resin with the hardener. EIS measurements confirmed that the presence and the increase of SiO2 nanoparticles greatly improved the corrosion resistance of the epoxy coating. The highest corrosion resistance for the coatings was obtained for the formulation with 5% SiO2 nanoparticles content, particularly with prolonging the immersion time to 30 days.

scholarly journals Protective properties of epoxy coatings electrodeposited on steel electrochemically modified by Zn-Fe alloys

2004 ◽  
Vol 58 (10) ◽  
pp. 450-456
Author(s):  
Jelena Bajat ◽  
Vesna Miskovic-Stankovic ◽  
Zorica Kacarevic-Popovic
Keyword(s):  
Prolonged Exposure ◽  
Passive Layer ◽  
Epoxy Coating ◽  
Constant Voltage ◽  
Epoxy Coatings ◽  
Corrosion Stability ◽  
Protective Properties ◽  
Water Oxygen ◽  
Current Densities ◽  
Fe Alloys

Epoxy coatings were electrodeposited on steel and steel modified by Zn-Fe alloys using the constant voltage method. Zn-Fe alloys were electrodeposited on steel at different current densities. The effect of the Zn-Fe alloy on the corrosion behavior of the epoxy coating was interpreted in terms of the electrochemical and transport properties. It was shown that the best properties, i.e. the largest values of the pore resistance and the smallest values of the coating capacitance, a longer period of almost constant Rp and Cp values, and the smallest diffusion coefficient of water through the epoxy coating, as well as the smallest amount of water absorbed inside the epoxy coating, were found for epoxy coatings on steel modified by a Zn-Fe alloy deposited at 4 A dm-2. During prolonged exposure to 3% NaCl, this Zn-Fe alloy significantly improves the corrosion stability of the epoxy coating: almost unchanged values of Rp and Rct were observed, due to the formation of a pseudo-passive layer of corrosion products, which is a good barrier to the transport of water, oxygen and electrolyte ions.

The effect of chemical treatment on the adhesion strength and structural integrity of the epoxy coatings

2021 ◽  
Author(s):  
Ameeq Farooq ◽  
Abdul Hannan ◽  
Rafiq Ahmad ◽  
Kashif Mairaj Deen
Keyword(s):  
Adhesion Strength ◽  
Chemical Treatment ◽  
Electrochemical Impedance ◽  
Degradation Mechanism ◽  
Epoxy Coating ◽  
Oxidation Products ◽  
Nacl Solution ◽  
Chemically Treated ◽  
Dry Film Thickness ◽  
Eis Analysis

Abstract This research aims to investigate the effect of chemical treatment on the integrity of the epoxy coating on mild steel substrates. Grit blasted steel samples were chemically treated in 10 vol.% NaOCl solution, 10 vol.% CrCl3 and 30 vol.% H3PO4 - 5 vol.% HNO3 solutions prior to coating application. Post-cleaning surface morphology and chemical composition revealed the formation of oxidation products on steel surface. Under optimized conditions, a dry film thickness of 135 ± 3 m of epoxy coating was achieved. The CT2 sample (pre-treated with CrCl3) presented higher coating adhesion strength (4.12 MPa) and the lowest rust area of 0.03 % compared to other chemically treated samples during 720 hours of immersion in 5 wt.% NaCl solution. The coating degradation mechanism was evaluated by electrochemical impedance spectroscopy (EIS) after 24, 48, 72 and 120 hours of immersion in 3.5 wt. % NaCl solution. EIS analysis of the coated samples pretreated with NaOCl and CrCl3 solutions exhibited low water uptake and limited corrosion due to hindrance in the diffusion of ionic species through the coating. However, coated steel samples pretreated in acidic solutions displayed appreciable corrosion damage as confirmed from saly spray and immersion tests. For instance, the delamination of the CT3 and CT4 (acid pre-treated) coatings was confirmed from the EIS analysis., which represented the formation of a double layer and occurrence of faradaic (corrosion) reactions as the coating-substrate interface, resulting in 15 – 30% delamination in 120 hours of exposure.

Comparison of Epoxy Coating Degradations Under Impingement Flow and Stationary Immersion

2020 ◽  
Author(s):  
Amin Vedadi ◽  
M. Subbir Parvej ◽  
Xinnan Wang ◽  
Yechun Wang
Keyword(s):  
Wind Turbines ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Epoxy Coating ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Corrosive Environment ◽  
Nacl Solution ◽  
Offshore Wind Turbines ◽  
The Impact

Abstract Offshore wind turbines are considered as a reliable source of electricity generation. However, due to the large cost of the construction and installation of offshore wind turbines, most wind turbines are designed to operate for more than 20 years. One of the biggest issues which causes a severe damage to the construction of wind turbines is the existence of a very corrosive environment including large mechanical loads applied to the construction by the waves and the high concentration of salt and other chemicals in the sea water. The construction of offshore wind turbine can be divided into four main regions based on the types of exposure to the water and the corrosive environment, including submerged zone, tidal zone, splash zone, and atmospheric zone. In this study, experiments were conducted to compare the impact of impingement flow of 3.5 w.t.% NaCl solution on the epoxy coating samples to the exposure of the same type of samples to a stationary 3.5 w.t.% NaCl solution. Those two exposure conditions correspond to the environments at the top and the bottom part of the submerged zone of offshore wind turbines respectively. Electrochemical Impedance Spectroscopy (EIS) method was used to monitor the degradation of organic coatings. The surface roughness was measured by Atomic Force Microscope (AFM). The roughness of the coated surfaces before and after the exposure was compared. For the two different flow conditions, i.e. impingement flow and stationary immersion, significant differences have been discovered from the EIS results and AFM results. We observed a more severe degradation in the epoxy coatings in impingement flow, and a rougher surface is formed for coating samples subjected to impingement flow.

scholarly journals Evaluation of protective properties of acrylate varnishes used for conservation of historical metal artefacts

2017 ◽  
Vol 61 (1) ◽  
pp. 25-31 ◽  
Author(s):  
J. Švadlena ◽  
J. Stoulil
Keyword(s):  
Air Pollutants ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Protective Properties ◽  
Paper Coatings ◽  
Metal Artefacts ◽  
Lower Permeability ◽  
Historical Objects ◽  
Acrylate Polymers ◽  
Permeability For Water

Abstract Acrylate varnishes are due to their suitable properties frequently used in restoration and preservation on variety of historical objects and materials. Common practice of their application involves using as an adhesive agents, consolidants and protective coatings. The purpose of protective coatings especially on metal artefacts is to reduce access of pollutants to the surface of the artefact. In this paper, coatings prepared from two acrylate polymers Paraloid B72 and Paraloid B48N are compared in terms of permeability for water and level of protective properties against air pollutants. For this purpose, electrochemical impedance spectroscopy and resistometric method were chosen for analysis of the coatings. Obtained results show lower permeability for water in case of Paraloid B72. However, same coating provided lower protection against air pollutants than Paraloid B48N coating.

scholarly journals Evaluation of the Corrosion Inhibiting Capacity of Silica/Polypyrrole-Oxalate Nanocomposite in Epoxy Coatings

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Van T. H. Vu ◽  
Thanh T. M. Dinh ◽  
Nam T. Pham ◽  
Thom. T. Nguyen ◽  
Phuong T. Nguyen ◽  
...  
Keyword(s):  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Epoxy Coating ◽  
Sodium Oxalate ◽  
Counter Anion ◽  
Epoxy Coatings ◽  
Protective Properties ◽  
Oxalate Anion

Silica/Polypyrrole nanocomposites (SiO2/PPy) incorporating oxalate as counter anion (SiO2/PPyOx) were chemically polymerized in the solution with the presence of pyrrole, silica, and sodium oxalate. Nanocomposites SiO2/PPyOx at different concentrations of oxalate anion were characterized with FTIR, XRD, EDX, TGA, and TEM. The corrosion protective properties for carbon steel of nanocomposites in epoxy coating were studied by electrochemical techniques including electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP). FTIR results of nanocomposites show a slightly red-shift in terms of wavelength compared with the case of PPy and SiO2 spectra. It may be due to a better conjugation and interactions between PPy and SiO2 in nanocomposite structure. TEM image indicated that nanocomposites have spherical morphologies with diameters between 100 and 150 nm. The EIS results showed that |Z| modulus values of epoxy coatings containing SiO2/PPyOx composites reached about 109.7 Ω.cm2, always higher than that of epoxy coating. These results are also confirmed by OCP results. It proves that the presence of oxalate anion can enhance the resistance against corrosion and it has been shown that the content of counter anion strongly affects the anticorrosion ability.

scholarly journals The effect of Zn-Ni sublayers on the corrosion behaviour and thermal stability of epoxy coatings electrodeposited on steel

2000 ◽  
Vol 65 (12) ◽  
pp. 923-933 ◽  
Author(s):  
Vesna Miskovic-Stankovic ◽  
Jelena Bajat ◽  
Miodrag Maksimovic ◽  
Zorica Kacarevic-Popovic
Keyword(s):  
Thermal Stability ◽  
Pulse Current ◽  
Corrosion Behaviour ◽  
Epoxy Coating ◽  
Epoxy Coatings ◽  
Corrosion Stability ◽  
Ni Alloys ◽  
Protective System ◽  
Thermal Stability Of ◽  
Protective Systems

The electrochemical and transport properties, as well as the thermal stability of epoxy coatings electrodeposited on steel and steel modified by Zn-Ni alloys were investigated during exposure to 3% NaCl. The Zn-Ni alloys were electrodeposited on steel using direct and pulse current. From the time dependence of the pore resistance of the epoxy coating (impedance measurements), the diffusion coefficient of water through the epoxy coating (gravimetric liquid sorption measurements) and the thermal stability of the epoxy coating (thermogravimetric analysis), it was shown that Zn-Ni sublayers significantly improve the corrosion stability of a protective system based on an epoxy coating. The values of the pore resistance were almost unchanged over a long period of immersion time for epoxy coatings on steel modified by Zn-Ni alloys, inidicating the great stability of these protective systems.

Deterioration of Enamel and Epoxy Coated Steel Rebar in 3.5 wt.% NaCl Solution

2012 ◽  
Vol 204-208 ◽  
pp. 4128-4136
Author(s):  
Fu Jian Tang ◽  
Xiao Ming Cheng ◽  
Gen Da Chen ◽  
Richard K. Brow ◽  
Jeffery S. Volz ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Open Circuit ◽  
Electrical Circuit ◽  
Nacl Solution ◽  
Porous Microstructure ◽  
Impact Tester ◽  
Potential Damage ◽  
Extent Of Damage ◽  
Equivalent Electrical Circuit Model

Reinforcing steel bars coated with pure enamel and fusion-bonded epoxy (FBE) were immersed in 3.5 wt.% NaCl solution for a period of 84 days. Predetermined damage of the coatings was created with a standard impact tester to study the coating resistance to potential damage caused during transportation and construction. Open-circuit potential and electrochemical impedance spectroscopy (EIS) tests were used to investigate deterioration processes of the two coating systems. An equivalent electrical circuit model was established to extract corrosion-indicative dielectric properties of enamel and FBE coatings from the EIS data. The change of coating capacitance over time was represented by a diffusion-controlled process. In comparison with the FBE coating with the same extent of damage, the enamel coating corroded sooner due to its thinner layer and porous microstructure, but deteriorated more slowly due to its robust bond with the steel substrate.

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