Polyaniline Inhibition of Corrosion-Driven Organic Coating Cathodic Delamination on Iron

Holness, R. J.; Williams, Geraint; Worsley, David; McMurray, H. N.

doi:10.1149/1.1850857

Cited by 93 publications

(122 citation statements)

References 67 publications

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“…It seems that even though PANI coating exists on Mg alloy surface, if the regular dissolution-precipitation reaction cannot be suppressed, a poor corrosion resistant product layer forms on Mg surface and further corrosion continues. A similar suggestion was also reported by Holness et al 50 and Williams et al 51 in the studies of the oxide layer growth at the PANI/iron interface, where the PANI-induced layer did not show a good protective performance and so thickened linearly with time in humid atmosphere. They attributed the poor corrosion resistance to the PANI, acting as a hydrous polyelectrolyte with a redox couple of polarizing.…”

Section: C301supporting

confidence: 85%

Growth Behavior of Initial Product Layer Formed on Mg Alloy Surface Induced by Polyaniline

Luo

Wang

Guo

et al. 2015

J. Electrochem. Soc.

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The quality of the interfacial protective layer induced by polyaniline (PANI) has been claimed to play a crucial role for the enhanced corrosion protection of Mg alloy, but its growth behavior is not well understood. Here some composition, structure and growth kinetics of the protective layer formed at the PANI-emeraldine base (EB) coating/AZ91D Mg alloy interface were investigated to explore the growth mechanism. Upon immersion in 0.5 M NaCl solution, the growing interface layer under EB coating exhibited a fast passivation rate and an increased corrosion resistance, which was largely influenced by ion concentration. XPS depth profiles showed that the EB-induced layer was a mixture of MgO and Mg(OH) 2 , in which no significant bi-layer structure existed and MgO was dominant throughout the bulk film. These observations suggest that the interaction between EB and Mg can promote the faster growth of a stable MgO-rich layer mixed with Mg(OH) 2 probably by solid reaction. Meanwhile less hydration of MgO and dissolution-precipitation reaction occur, thus leading to less Mg(OH) 2 in the outer layer. Magnesium alloys have drawn great attention in automotive and aerospace industry due to their excellent properties such as low density and high specific strength. However, limited corrosion resistance of such alloys has retarded their widespread applications. To improve the corrosion resistance of Mg alloys, numerous coating techniques have been explored, among which organic coating containing corrosion inhibiting pigments is an economical and effective method in industry. One important pigment for Mg alloys is polyaniline (PANI) including emeraldine salt form (ES) and emeraldine base form (EB). 1-6Its highly efficient corrosion-protection performance for Mg alloys has been shown to be competitive to a chromate-pigmented coating. Additionally, self-healing capability was also found on a hybrid solgel/PANI coated Mg alloy upon immersing in Harrison's solution, where no pitting or filiform corrosion occurred around the scratched area while a protective layer was formed.8 Sathiyanarayanan et al. 1 and Wang et al. 8 observed that, after an initial decrease upon immersion in corrosive electrolytes, the complex impedance of PANI coated Mg alloy recovered, which was attributed to the formation of a protective layer. The different chemical composition on the EB-induced protective layer surface was already confirmed by X-ray photoelectron spectroscopy (XPS) in comparison with that formed underneath a varnish coating. 2,6The mechanism of PANI promoting a protective layer formation has been mostly supported by extensive studies in various metal systems.9-14 Nevertheless, few works have been done to understand the protective layer growth behavior. The most intractable issue of how the interaction between PANI and metal induces the protective layer growth still remains unsolved.9 This is attributed primarily to the great difficulty in in-situ investigation on the growth kinetics of interfacial layer formed beneath a coating. Electroche...

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Section: C301supporting

confidence: 85%

Growth Behavior of Initial Product Layer Formed on Mg Alloy Surface Induced by Polyaniline

Luo

Wang

Guo

et al. 2015

J. Electrochem. Soc.

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“…A full explanation of SKP apparatus, calibration procedure and calibration plots are given elsewhere. 26 X-Ray photoelectron spectra (XPS) were recorded on a Kratos Axis Supra instrument (Kratos Analytical, Manchester, UK) using a monochromated Al Kα source and detector in large area slot mode (∼300 × 800 μm analysis area). All spectra were recorded using a charge neutralizer to limit differential charging.…”

Section: Re Fmentioning

confidence: 99%

A Scanning Kelvin Probe Investigation of the Interaction of PEDOT:PSS Films with Metal Surfaces and Potential Corrosion Protection Properties

Glover¹,

McGettrick²,

Williams³

et al. 2015

J. Electrochem. Soc.

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The study of conducting polymers (CPs) is of high current interest due to their wide application in a range of optical and electronic devices. Poly(3,4-Ethylenedioxythiophene)-Poly(Styrene Sulfonate) (PEDOT:PSS) is considered one of the most electrochemically and thermally stable CPs currently available. In many applications there is a requirement for electrical contact to be made between an organic PEDOT:PSS layer and a metallic substrate. In order to gauge the long term stability of the metal-CP interface, an understanding of the interaction between the CP and various metals is of high importance. An in-situ scanning Kelvin probe (SKP) has been employed to measure the Volta potential differences of PEDOT:PSS-coated metals of interest in opto-electronic device manufacture, including Ni, Cu, Ag and Pt, with noble metals for comparison, to identify instances where a reaction is taking place at the interface. A redox potential of ca. −0.15 V vs. SHE has been shown where PEDOT:PSS is present in both oxidized and reduced form on the metal surfaces. Poly(3,4-Ethylenedioxythiophene)-Poly(Styrene Sulfonate) (PE-DOT:PSS) is utilized as a thin, transparent conductor in a range of optical and electronic devices such as organic light-emitting diodes (OLED)1,2 touch screen panels 3 and third generation photovoltaic devices such as Dye Sensitized Solar Cells (DSSC), Organic Photovoltaics (OPV) and hybrid organic/inorganic perovskite-type cells. [4][5][6][7][8] PEDOT:PSS has also proven to be an effective replacement for antistatic surfaces where, unlike traditional ionic antic-static agents, it provides a lower surface resistance that is practically independent of atmospheric humidity. Such systems are now widely used in packaging of electronic components 9 and the production and processing of photographic films. 10 Compared with other thiophenes, PEDOT:PSS displays good electrochemical, ambient and thermal stability of its electrical properties, it has high electrical conductivity and good film forming ability. [11][12][13] It is also light-weight with good mechanical flexibility -a major advantage for architectural applications and wearable devices. 14,15 Much research has been conducted into the replacement of the expensive Pt counter electrode (CE) of a dye-sensitized solar cell (DSSC).16 PEDOT:PSS is widely considered to be an ideal candidate due to its high conductivity, electrochemical stability and its stability in the oxidized state where catalytic activity for the reduction of the I 2 to I − mediator in the redox electrolyte is required. 17,18 Furthermore, in many applications there is a requirement for good electrical contact to be made with the organic PEDOT:PSS layer and, for energy conversion devices in particular, stability over a sustained time period is imperative. As such, the expensive noble metals Au and Ag are typically used but, as with the DSSC Pt counter-electrode, it is necessary to determine whether a more cost-effective alternative would be equally inert when over-coated using PEDOT:PSS.The aim of ...

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“…Atomic Force Microscopy (AFM) is an exciting new technique that allows surface to be imaged at higher resolutions and accuracies than ever before [40][41][42]. The microscope used for the present study was PicoSPM I Molecular Imaging, USA.…”

Section: Atomic Force Microscopymentioning

confidence: 99%

Inhibition of Corrosion of Carbon Steel in Sea Water by Sodium Gluconate - Zn2+ System

Rajendran

Anuradha²,

Kavipriya

et al. 2013

Port. Electrochim. Acta

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The inhibition efficiency of sodium gluconate (SG)-Zn 2+ system in controlling corrosion of carbon steel in sea water has been evaluated by weight-loss method. The formulation consisting of 250 ppm of SG and 75 ppm of Zn 2+ has 98% IE. Influence of duration of immersion on the IE of SG-Zn 2+ has been evaluated. The mechanistic aspects of corrosion inhibition have been investigated by polarization study and AC impedance spectra. The protective film has been analysed by FTIR and luminescence spectra. The surface morphology and the roughness of the metal surface have been analysed by atomic force microscopy. The protective film consists of Fe 2+ -SG complex and Zn(OH) 2 . It is found to be UV -fluorescent.

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Polyaniline Inhibition of Corrosion-Driven Organic Coating Cathodic Delamination on Iron

Cited by 93 publications

References 67 publications

Growth Behavior of Initial Product Layer Formed on Mg Alloy Surface Induced by Polyaniline

Growth Behavior of Initial Product Layer Formed on Mg Alloy Surface Induced by Polyaniline

A Scanning Kelvin Probe Investigation of the Interaction of PEDOT:PSS Films with Metal Surfaces and Potential Corrosion Protection Properties

Inhibition of Corrosion of Carbon Steel in Sea Water by Sodium Gluconate - Zn2+ System

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