Electrochemical impedance spectroscopy and linear polarization applied to evaluation of porosity of phosphate conversion coatings on electrogalvanized steels

Lins, Vanessa de Freitas Cunha; Reis, Geraldo Francisco de Andrade; Araújo, Carlos Roberto de; Matencio, Túlio

doi:10.1016/j.apsusc.2006.06.030

Cited by 78 publications

(23 citation statements)

References 21 publications

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“…The small potential difference between the substrate and the coating allows that the substrate current density can be used in the porosity measurement. The coating porosity can be evaluated using following equation [7]:…”

Section: Coating Porositymentioning

confidence: 99%

See 1 more Smart Citation

Nano-TiO2 Phosphate Conversion Coatings – A Chemical Approach

Bagal¹,

Kathavate²,

Deshpande

2018

Electrochemical Energy Technology

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The present study aims at deposition of zinc phosphate coatings on low carbon steel with incorporated nano-TiO 2 particles by chemical phosphating method. The coated low carbon steel samples were assessed in corrosion studies using electrochemical impedance spectroscopy and potentiodynamic polarization techniques (Tafel) in 3.5% NaCl solution. Morphology and chemical composition of the coatings were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy in order to observe growth of coating. Significant variations in the coating weight, porosity and corrosion resistance were observed with the addition of nanoTiO 2 in the phosphating bath. Corrosion rate of nano-TiO 2 chemical phosphate coated samples was found to be 3.5 milli inches per year which was 3 times less than the normal phosphate-coated sample (8 mpy). Electrochemical impedance spectroscopy studies reveal reduction of porosity of nano-TiO 2 phosphate coated samples. It was found that nano-TiO 2 particles in the phosphating solution yielded uniform phosphate coatings of higher coating weight, fewer defects and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal phosphating bath).

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Section: Coating Porositymentioning

confidence: 99%

“…However, each of them has some limitations and/or detrimental effects. Chemical accelerators are the preferred choice in many instances [7]. It should be stressed that, while phosphate coatings always affect corrosion protection, its effects are not always necessarily positive.…”

Section: Introductionmentioning

confidence: 99%

Nano-TiO2 Phosphate Conversion Coatings – A Chemical Approach

Bagal¹,

Kathavate²,

Deshpande

2018

Electrochemical Energy Technology

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“…Having said that, the R p values are relatively high compared to those generally mentioned in literature and obtained with experimental conditions less aggressive than those we used. 14,22,24 …”

Section: Evaluation Of the Anticorrosive Properties Of Papsmentioning

confidence: 99%

Phosphonic acid‐containing polysulfones as anticorrosive layers

Chauveau

Marestin

Merçier

et al. 2015

J of Applied Polymer Sci

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International audienceAs a part of research work to elaborate polymeric materials for metal corrosion protection, we have developed a new family of phosphonic acid-containing polymers. The synthesis and the characterization of polysulfones bearing alkyl phosphonate ester side groups are first described. These polymers are synthesized by direct polycondensation of a phosphonate ester-containing bisphenol by aromatic nucleophilic substitution. The physicochemical properties of the resulting polymers are described. Acidic hydrolysis of phosphonate esters results in the formation of phosphonic acid groups. A series of phosphonic acid-containing polysulfones is therefore obtained and characterized. A preliminary evaluation of the anticorrosive properties of these polymers is described. In 0.25M Na2SO4 solution, the corrosion rate of a polymer-coated mild steel sample is much lower than of the free metal substrate. These results suggest that phosphonic acid-containing polysulfones might be interesting as anticorrosive coatings

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“…A wider use of phosphate films for corrosion protection of Zn and Zn alloy coatings is restricted by the existence of open pores and pinholes in the films [24]. As the corrosion reactions are initiated at the coating-substrate interface, therefore, the production of the phosphate films with reduced porosity is appreciated.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

“…The determination of porosity is an important task in controlling the quality of phosphate films. This parameter could be estimated by applying electrochemical measurements and by determining oxidation and reduction rates on the sample surface [24].…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%