Inhibition of corrosion-driven organic coating disbondment on galvanised steel by smart release group II and Zn(II)-exchanged bentonite pigments

Williams, Geraint; McMurray, H. N.; Loveridge, Melanie

doi:10.1016/j.electacta.2009.10.059

Cited by 73 publications

(52 citation statements)

References 66 publications

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“…[1][2][3][4] However, due to concerns regarding the toxicity of chromium (VI)-containing compounds, the use of SrCrO 4 has been restricted, 5) and the search for an alternative to chromate base pigments has been extensive. 1,[6][7][8][9][10][11][12][13][14] Phosphate pigments are traditional and promising alter-…”

Section: Introductionmentioning

confidence: 99%

Effect of Phosphate and Chromate Pigments on Sacrificial Corrosion Protection by Al–Zn Coating and Delamination Mechanism of Pre-painted Galvalume Steel

et al. 2016

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Section: Introductionmentioning

confidence: 99%

Effect of Phosphate and Chromate Pigments on Sacrificial Corrosion Protection by Al–Zn Coating and Delamination Mechanism of Pre-painted Galvalume Steel

et al. 2016

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“…[17][18][19][20][21] In such studies, the use of model organic coatings allows a systematic study of the influence of pigment loading on both the rates of corrosion-driven delamination and corrosion cell potentials, which in turn provides information regarding the prevailing mechanisms of underfilm inhibition.…”

Section: -16mentioning

confidence: 99%

“…[12][13][14][15][16] In addition, in-situ SKP methodologies have been extensively used to evaluate the efficiency of various types of corrosion inhibitive pigments in the protection of HDG surfaces. [17][18][19][20][21] In such studies, the use of model organic coatings allows a systematic study of the influence of pigment loading on both the rates of corrosion-driven delamination and corrosion cell potentials, which in turn provides information regarding the prevailing mechanisms of underfilm inhibition.…”

mentioning

confidence: 99%

In-Coating Phenyl Phosphonic Acid as an Etch-Primer Corrosion Inhibitor System for Hot Dip Galvanized Steel

Glover

Subramanian

Williams

2015

J. Electrochem. Soc.

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In-coating phenyl phosphonic acid (H 2 PP) additions are investigated as inhibitors of corrosion-driven organic coating disbondment on hot-dip galvanized (HDG) steel surfaces. In-situ scanning Kelvin probe (SKP) experiments under atmospheric corrosion conditions are used to study the influence of the quantity of dissolved H 2 PP in the organic coating on the kinetics of delamination. It is demonstrated that increasing levels of in-coating H 2 PP progressively lengthen the time for organic coating delamination to become established. Once underfilm corrosion becomes initiated, rates of cathodic disbondment are significantly slowed by H 2 PP additions in comparison with the uninhibited case. From the observed delamination kinetics, an inhibition mechanism is proposed whereby H 2 PP additions interact with the underlying zinc to form an interfacial salt layer which blocks underfilm oxygen reduction. The contribution of other possible modes of inhibition, such as H 2 PP release from the coating into the external defect electrolyte and a buffering of underfilm pH, are also discussed. There is significant current interest in replacing conventional corrosion protection technologies, based on an initial pre-treatment and subsequent application of organic-based primer, with a single coating system for metal surfaces. The pre-treatment step typically produces a thin inorganic layer which improves organic coating adhesion to the metal surface and provides a degree of corrosion protection.1-4 Additional corrosion protection is afforded by dispersions of sparingly soluble inorganic salt inhibitor pigments within the organic-based primer, where the constituent ions will leach out and dissolve on water contact with exposed regions of coating.5 Passivation of the metal surface at coating defect regions is achieved by the subsequent build up of an insoluble metallic/salt layer which blocks electron transfer. 6 An alternative to a two-step corrosion protection system is an etch primer, which traditionally comprises a suspension of chromate pigment in a polyvinyl butyral (PVB) alcohol solution, mixed with a phosphoric acid-based activator prior to application.7 A reaction occurs at the point of first contact of the wet coating with the substrate 8 producing an interfacial metal phosphate salt layer, which in combination with the dispersed chromate pigment, provides the required protection against corrosion. However, with current legislative pressure to eliminate Cr(vi)-based inhibitors from protective coating formulations, there is a pressing need to identify effective, yet environmentally acceptable alternatives. In this current study a potential Cr(vi)-free etch primer system, based on phenylphosphonic acid (H 2 PP), which acts as both activator and in-coating inhibitor is investigated. Previous studies have demonstrated the effective inhibition of corrosion (on iron surfaces) by polymeric, H 2 PP-doped polyaniline blends. The formation of an electron-blocking, insoluble salt complex of combined H 2 PP and divalent metal cations,...

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“…Insoluble ion exchange compounds have been identified and proven to be 'pigment grade' compounds [52,[82][83][84][85][86]. The required amount of inhibitor cations or anions are held and delivered when they come in contact with an aggressive electrolyte.…”

Section: Introductionmentioning

confidence: 99%

“…AA 2024-T3 coupons coated with an epoxy containing Ce(III) bentonite pigment showed resistance to blistering and modest corrosion protection after 3000 h of salt spray exposure [80]. Williams et al have shown that Ce bentonite and Zn bentonite compounds have reduced the cathodic delamination on galvanized steel substrates [85,86].…”

Section: Introductionmentioning

confidence: 99%

Scientific Understanding of Non-Chromated Corrosion Inhibitors Function

Frankel¹,

Buchheit²,

Jaworowski³

et al. 2013

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Inhibition of corrosion-driven organic coating disbondment on galvanised steel by smart release group II and Zn(II)-exchanged bentonite pigments

Cited by 73 publications

References 66 publications

Effect of Phosphate and Chromate Pigments on Sacrificial Corrosion Protection by Al–Zn Coating and Delamination Mechanism of Pre-painted Galvalume Steel

Effect of Phosphate and Chromate Pigments on Sacrificial Corrosion Protection by Al–Zn Coating and Delamination Mechanism of Pre-painted Galvalume Steel

In-Coating Phenyl Phosphonic Acid as an Etch-Primer Corrosion Inhibitor System for Hot Dip Galvanized Steel

Scientific Understanding of Non-Chromated Corrosion Inhibitors Function

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