In situ electrochemical studies of forming-induced defects of organic coatings on galvanised steel

Klüppel, Ingo; Schinkinger, B.; Grundmeier, Guido

doi:10.1016/j.electacta.2009.01.003

Cited by 19 publications

(8 citation statements)

References 23 publications

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“…However, this does not mean a thick organic coating is defect free, particularly after long-term service. It is possible to modify the defects through altering the coating curing conditions, such as temperature, pressure and airflow [66][67][68]. [56].…”

Section: Defects and Defect-modificationmentioning

confidence: 99%

“…It has been reported that under salt spray or immersion condition, coatings with controlled defects can significantly accelerate the substrate corrosion and the coating peeling [172][173][174][175]. However, the defects naturally formed during curing are quite random in number, size and distribution, which cannot be easily adjusted to modify the overall corrosion performance of a coating system [67]. To rapidly reveal coating failure mechanism, controllable defects in organic coatings are needed.…”

Section: Scratchmentioning

confidence: 99%

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Modification, Degradation and Evaluation of a Few Organic Coatings for Some Marine Applications

Song

Feng

2020

CMD

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Organic coatings for marine applications must have great corrosion protection and antifouling performance. This review presents an overview of recent investigations into coating microstructure, corrosion protection performance, antifouling behavior, and evaluation methods, particularly the substrate effect and environmental influence on coating protectiveness, aiming to improve operational practice in the coating industry. The review indicates that the presence of defects in an organic coating is the root cause of the corrosion damage of the coating. The protection performance of a coating system can be enhanced by proper treatment of the substrate and physical modification of the coating. Environmental factors may synergistically accelerate the coating degradation. The long-term protection performance of a coating system is extremely difficult to predict without coating defect information. Non-fouling coating and self-repairing coatings may be promising antifouling approaches. Based on the review, some important research topics are suggested, such as the exploration of rapid evaluation methods, the development of long-term cost-effective antifouling coatings in real marine environments.

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Section: Defects and Defect-modificationmentioning

confidence: 99%

Section: Scratchmentioning

confidence: 99%

Modification, Degradation and Evaluation of a Few Organic Coatings for Some Marine Applications

Song

Feng

2020

CMD

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“…The equivalent circuits consisted of the solution resistance, Rs, the polarisation resistance, Rp, and double-layer capacitance, Cdl, [19] shown in Figure 2. For modelling the interface of a metal surface in contact with an electrolyte, as well as to describe non-porous coating behaviour, the Randles equivalent circuit is often used [20]. After 100 h of exposure to a 4% w/w NaOH solution, the Nyquist diagram for all tested powder coatings showed a two-time constant spectrum, thus the impedance data were fitted with the equivalent electric circuit for porous coating.…”

Section: Ocp and Eis Studymentioning

confidence: 99%

Experimental Evaluation of Polyester and Epoxy–Polyester Powder Coatings in Aggressive Media

et al. 2018

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Protective coatings are the most widely used corrosion protection method for construction materials in different environmental conditions. They isolate metals from aggressive media, making the structure more durable. Today, alongside good anti-corrosive properties, coatings need to be safe for the environment and harmless to those who apply them. The high volatile organic compound (VOC) content in conventional solvent-borne coatings presents a huge ecological problem. A solution for indispensable solvent emission reduction is the application of powder coatings. This study evaluates the corrosion performance and surface morphology of polyester and epoxy-polyester powder coatings. Electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) measurement, salt spray chamber and humidity chamber testing followed by adhesion testing were used to investigate the protective properties of powder coatings. Scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX) was used to analyse the surface morphology and chemical composition, whereas the microstructure and coating uniformity were determined by optical microscope examination. The research revealed a negative influence of coating surface texture on coating thickness and consequently a lack of barrier and adhesion properties. The epoxy-polyester powder coating showed a better performance than the polyester coating. All tested coatings showed uniform structure.Coatings 2018, 8, 98 2 of 12 coating [1]. Today, thanks to the commercial success and wide application of powder coatings, extensive research is carried out in this field of study, in particular in the powder coating chemistry [5].Compared to liquid paints, powder coatings feature several advantages including the absence of volatile organic content, the reduction in coating material loss (up to 68%), the reduction of dust formation (from 40% to 84%) [1], high utilization rates, fast curing, the minimal health risks involved, and the elimination of hazardous wastes [7]. However, a major disadvantage of electrostatic coating technology is that the curing of the powder coating requires a significant amount of heat energy. For this reason, the future of these technologies will include the development of low temperature curable (LTC) powder coatings, whose application will enable energy saving solutions and also the ability to coat heat-sensitive substrates [8]. The second disadvantage is the lack of coating uniformity in Faraday-cage areas. Aside from several challenges needing improvement, powder coating is an environmentally-friendly coating process with good performance properties.There are numerous methods to evaluate the corrosion performance of powder coatings. Mafi et al. [5] investigated the protective behaviour of powder coatings in 3.5% w/w NaCl solution using electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) measurement, as well as differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Bhadu et al. [9] studied...

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“…Thereby, it is possible for the defects to be modified on purpose by altering the curing conditions, such as temperature, pressure, and airflow. Different from an open macrodefect by scratching techniques, the curing environment modification allows microdefects to form and grow naturally, which is normally favored in studies . Apart from natural environmental factors, some artificial conditions, such as electric, magnetic, and electromagnetic fields are also environmental parameters that have a contactless power to modify the morphology and property of polymer materials .…”

Section: Introductionmentioning

confidence: 99%

“…Different from an open macrodefect by scratching techniques, the curing environment modification allows microdefects to form and grow naturally, which is normally favored in studies. [12,21,22] Apart from natural environmental factors, some artificial conditions, such as electric, magnetic, and electromagnetic fields are also environmental parameters that have a contactless power to modify the morphology and property of polymer materials. [23] Recently, the electric field was reported to be able to alter the distribution of the microdefects locally in an organic coating and thus enhance the coating protectiveness there.…”

Section: Introductionmentioning

confidence: 99%

Modification of an alkyd resin coating by airflow

Feng

Wang

Song

et al. 2019

Materials & Corrosion

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The anti‐permeability of an alkyd coating was modified by controlled airflow during the curing process. After the immersion test, the thinner airflow‐modified region had the best anti‐permeability compared with other thicker regions. The abnormal permeation behavior could be attributed to the difference in air pressure caused by the airflow. A model involving solvent evaporation and defect formation processes was proposed to interpret the airflow affected abnormal permeation behavior. This defect modification method may be employed to improve the corrosion resistance of an alkyd coating in a selected area and improve the painting quality in practice.

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In situ electrochemical studies of forming-induced defects of organic coatings on galvanised steel

Cited by 19 publications

References 23 publications

Modification, Degradation and Evaluation of a Few Organic Coatings for Some Marine Applications

Modification, Degradation and Evaluation of a Few Organic Coatings for Some Marine Applications

Experimental Evaluation of Polyester and Epoxy–Polyester Powder Coatings in Aggressive Media

Modification of an alkyd resin coating by airflow

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