A study on mechanism of corrosion protection of polyaniline coating and its failure

Fang, Jianjun; Xu, Ke; Zhu, Lihua; Zhou, Zhixiong; Tang, Heqing

doi:10.1016/j.corsci.2007.05.017

Cited by 129 publications

(58 citation statements)

References 27 publications

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“…49 Unlike anodic protection observed in conducting polymer coated stainless steels, 49 which display a passivation zone upon anodic polarization, PEDOT coated Mg alloys confer a limited corrosion protection due to the barrier effect. Indeed, the PEDOT coating reduces the rate of the anodic and cathodic reactions on AZ31B (shown by the localized PDP curves).…”

Section: Discussionmentioning

confidence: 99%

Localized Corrosion Behavior of AZ31B Magnesium Alloy with an Electrodeposited Poly(3,4-Ethylenedioxythiophene) Coating

Tefashe

Dauphin‐Ducharme

Danaie

et al. 2015

J. Electrochem. Soc.

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Herein we report the characterization of localized corrosion of AZ31B magnesium alloy electrochemically coated with poly(3,4-ethylenedioxythiophene) (PEDOT) from ionic liquid electrolyte. Several scanning probe techniques including high resolution electron microscopy, SVET, SECM amperometric detection of H 2 fluxes, potentiometric SECM detection of local pH and localized potentiodyanmic measurements were used to evaluate the microstructure of the coating and its corrosion protectiveness. In order to examine long-term durability of corrosion protection due to the PEDOT coating, these measurements were performed after different immersion times. It was observed that PEDOT coating appears to lose its protective ability after localized coverage of corrosion products. The results of this study provide important information considering the interest in this coating for use in biomedical implants and prior indications of beneficial passivation. Replacement of heavy alloy components with light-weight materials is of prime concern for automotive and aerospace manufacturers in order to reduce the fuel consumption and hence polluting CO 2 emissions. Magnesium alloys are one of the potential candidates owing to their excellent physical and mechanical properties such as lower density, a higher strength-to-mass ratio and a higher vibrational damping capacity compared to steel and aluminum alloys.1 However, the high corrosion susceptibility is the major drawback preventing more widespread use of such Mg-based alloys.The addition of alloying elements, alternate processing technologies and surface coatings are effective in improving the corrosion performance of Mg-based alloys.2,3 Dip coating is particularly attractive to the automotive industry because of its simplicity, low costs and great coverage ability. 4,5 Coating processes vary from the widely used chromate/manganese dip treatment to anodic treatments in fluoridecontaining baths, 6,7 and are generally considered hazardous to human health and to the environment.2,3 More environmentally sustainable surface modification processes were identified in conductive polymers but remain challenging to implement with light metal alloys. 8,9 Conducting polymer films are readily formed by direct electrodeposition onto Pt and Au.10 They have been used for corrosion protection of structural metal like steel and aluminum with success but comprehensive investigations for magnesium materials is lacking. The deposition of conductive polymers onto Mg-based electrodes from aqueous solutions is generally not feasible because the positive potentials required for electropolymerization concurrently form thick surface oxide films and lead to copious hydrogen evolution 11,12 that prevent the formation of adherent and continuous conducting polymer films. 13Room temperature ionic liquids (RTIL's) are increasingly being applied in electrochemistry 14 and have recently been explored as solvents for the electropolymerization of conducting polymers. [15][16][17] Generally, conducting polymers prepared from...

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Section: Discussionmentioning

confidence: 99%

Localized Corrosion Behavior of AZ31B Magnesium Alloy with an Electrodeposited Poly(3,4-Ethylenedioxythiophene) Coating

Tefashe

Dauphin‐Ducharme

Danaie

et al. 2015

J. Electrochem. Soc.

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“…Their advantages include high electrical conductivity, low cost, and possibility of reducing environmental pollution [8,9]. Redox and catalytic activity of these materials promote formation of an oxyhydroxide layer on the polymer-metal interface [10][11][12], which passivates the metal surface and prevents it from corrosion; on the other hand, it causes instability of the electrical characteristics of the contact between the polymeric and metal phases [13]. Currently, the research in the field was mainly focused on the electrochemical investigations of the corrosion processes [14][15][16][17][18], but the oxide layer composition was not determined because of difficulties in applying ex situ experimental techniques [19,20].…”

Section: Introductionmentioning

confidence: 99%

Interaction of Polyaniline with Surface of Carbon Steel

Sokolova

Смирнов

Kasatkin

et al. 2017

International Journal of Polymer Science

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The structure and barrier properties of the oxyhydroxide layers on a carbon steel surface covered with electroactive polyaniline were investigated. Two types of polymer structure differing in degree of macromolecular order were prepared by simultaneous (fast polymerization) or dropwise (slow polymerization) mixing of reagents. A larger amount of the most stable FeOOH modification was formed on steel covered with slowly polymerized sample during treatment in the corrosion-active medium. Amorphous rust products with weak barrier properties were observed in the sample prepared by fast polymerization. Additionally, barrier activity of dedoped polyaniline was studied with SEM, WAXD, and electrochemical methods.

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“…The conducting polymers, which possess the electronic properties of semiconductors and processing advantages of conventional polymers, have widely been studied for corrosion protection during the last few years. Since the first reported work on the corrosion protection of metals using conducting polymers in 1981 [4], a large number of studies with focus mainly on polyaniline [5][6][7][8][9][10] and polypyrrole [11][12][13][14][15] have been carried out. Nevertheless, the polyaniline is more challengeable due to low cost of aniline monomers as compared to pyrrole, its environmental stability and the easy solution processing.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behavior of Chemically Deposited Single and Bi-layered Conducting Polymer Coatings on Mild Steel

Mobin

Tanveer

2011

Port. Electrochim. Acta

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The emeraldine base (EB) was synthesized by chemically oxidative polymerization using ammonium persulphate as an oxidant in hydrochloride aqueous medium. The polymer was chemically deposited on mild steel specimens using tetra methyl urea (TMU) as solvent through solvent evaporation method. The coating of polypyrrole (PPy) on carbon steel was deposited by chemical polymerization. A bi-layered polymer coating comprising of inner coat of PPy with top coat of EB (PPy/EB) was also deposited on mild steel following identical procedure. The deposited EB, PPy and PPy/EB coatings were characterized by Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM). The anticorrosive properties of single and bi-layered coatings was investigated in major corrosive environments such as 0.1 M HCl, 5% NaCl solution, artificial seawater, distilled water, tap water and open atmosphere by conducting various corrosion tests which include: immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The results of immersion tests showed that the PPy/EB coating gave best protection in all media under investigation, the protection efficiency being in the range of 72 to 79% after 30 days of immersion. The result of OCP measurements showed significant positive shift in the corrosion potential for single as well as bi-layered coatings in all corrosive medium under investigation; the bi-layered coating showing more positive corrosion potential. The potentiodynamic polarization studies also confirmed lower corrosion rates for PPy/EB coating than the single polymer coatings.

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A study on mechanism of corrosion protection of polyaniline coating and its failure

Cited by 129 publications

References 27 publications

Localized Corrosion Behavior of AZ31B Magnesium Alloy with an Electrodeposited Poly(3,4-Ethylenedioxythiophene) Coating

Localized Corrosion Behavior of AZ31B Magnesium Alloy with an Electrodeposited Poly(3,4-Ethylenedioxythiophene) Coating

Interaction of Polyaniline with Surface of Carbon Steel

Corrosion Behavior of Chemically Deposited Single and Bi-layered Conducting Polymer Coatings on Mild Steel

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