D.M. Santágata, P.R. Seré, S. Hornus Sack, I. Elsner, G. Mendivil and A.R. Di Sarli
The effect of different kind of pigments on the corrosion resistance properties of an epoxy paint has been investigated using electrochemical impedance spectroscopy and open…
Abstract
The effect of different kind of pigments on the corrosion resistance properties of an epoxy paint has been investigated using electrochemical impedance spectroscopy and open circuit potential measurements. Painted naval steel samples were studied during the exposure to artificial sea water. The epoxy paint coatings were prepared employing red lead, zinc, red iron oxide or titanium dioxide as pigment with 0.8 of PVC/CPVC ratio. From the EIS and corrosion potential data analyis was found that the anticorrosive protection given by an anticorrosive (pigmented with red lead) and a top coat (pigmented with red iron oxide) epoxy painting scheme was both more lasting and more effective. This was attributed to the fact that both the effective adhesion provided by the chemical bonding between the steel surface and the epoxy paint groups and the constant high barrier effect afforded by this type of top coat were a perfect complement for the high corrosion inhibitive capacity of the red lead pigment.
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D.M. Santágata, P.R. Seré, S. Hornus Sack, C.I. Elsner, G. Mendivil and A.R. Di Sarli
The effect of different kind of pigments on the corrosion resistance properties of an epoxy paint has been investigated using electrochemical impedance spectroscopy and open…
Abstract
The effect of different kind of pigments on the corrosion resistance properties of an epoxy paint has been investigated using electrochemical impedance spectroscopy and open circuit potential measurements. Painted naval steel samples were studied during the exposure to artificial sea water. The epoxy paint coatings were prepared employing red lead, zinc, red iron oxide or titanium dioxide as pigment with 0.8 of PVC/CPVC ratio. From the EIS and corrosion potential data analyis was found that the anticorrosive protection given by an anticorrosive (pigmented with red lead) and a top coat (pigmented with red iron oxide) epoxy painting scheme was both more lasting and more effective. This was attributed to the fact that both the effective adhesion provided by the chemical bonding between the steel surface and the epoxy paint groups and the constant high barrier effect afforded by this type of top coat were a perfect complement for the high corrosion inhibitive capacity of the red lead pigment.
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J.J. Caprari, A.R. Di Sarli and B. del Amo
Health and safety legislation has forced changes in the type of anticorrosive pigments used in paint formulations, mainly focused on their substitution with different phosphates…
Abstract
Health and safety legislation has forced changes in the type of anticorrosive pigments used in paint formulations, mainly focused on their substitution with different phosphates. The zinc phosphate pigment used with different types of binders has provided contradictory experimental results. In this paper, waterborne anticorrosive paints pigmented with zinc phosphates were studied. The main variables considered were PVC and the anticorrosive pigment content. Accelerated tests (salt spray, humidity chamber, and electrochemical tests) were performed to evaluate the paints’ anticorrosive performance. Good correlation was found using salt spray and impedance tests. From analysis of the time dependence of all the experimental results it was concluded that an efficient steel protection could be obtained using a waterborne epoxy primer pigmented with zinc phosphate. Such protection is attained through the barrier effect afforded by the paint film as well as the precipitation of a pretty stable ferric phosphate layer under the intact and damaged coating areas.
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L.S. Hernández, B. del Amo and R. Romagnoli
Substitution of zinc chromate or zinc yellow, traditionally used as anticorrosive pigment, for other phosphate‐based pigments that are not hazardous to health and have the same…
Abstract
Substitution of zinc chromate or zinc yellow, traditionally used as anticorrosive pigment, for other phosphate‐based pigments that are not hazardous to health and have the same anticorrosive behaviour or even better, is studied in this paper. Four alkyd paints were specially prepared; two of them contained calcium acid phosphate or micronised zinc phosphate as anticorrosive pigments respectively. A paint containing zinc chromate was used as reference and a paint without anticorrosive pigments was used as a blank, in which the other ingredients were increased proportionally to attain the desired PVC relationship. The corrosion behaviour of low carbon steel panels coated with these paints in a 3 per cent NaCl solution was assessed by electrochemical impedance spectroscopy (EIS). In addition, other painted panels were evaluated by salt spray and humidity chamber tests. Results of all tests showed that the paint with calcium acid phosphate and especially that with micronised zinc phosphate exhibited better behaviour than paint with zinc chromate. Analysis of impedance parameters (ionic resistance and capacitance of the paint film) against immersion time allowed the paints to be ranked in the same order as that obtained with salt spray and humidity chamber tests.
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Yuhua Dong, Chundong Geng, Xiang Wang and Qiong Zhou
This paper aims to investigate effect of porous polystyrene microspheres encapsulated inhibitor on the protection performance of epoxy resin coating.
Abstract
Purpose
This paper aims to investigate effect of porous polystyrene microspheres encapsulated inhibitor on the protection performance of epoxy resin coating.
Design/methodology/approach
Porous polystyrene (PS) microspheres were synthesized by soap-free emulsion polymerization. The morphology of microspheres was observed by scanning electron microscopy and transmission electron microscopy. Corrosion inhibitor benzotriazole was encapsulated into porous PS microspheres. The protection performance of epoxy resin coating with different contents of PS microspheres was tested by polarization curve.
Findings
The findings of electrochemical impedance spectroscopy and scanning vibrating electrode technique showed that addition of corrosion inhibitor to porous PS microspheres further improved the protection performance of the coatings.
Practical implications
Porous PS microspheres could be used as nanocontainer to encapsulate corrosion inhibitor.
Originality/value
Addition of porous PS microspheres with corrosion inhibitor improved the protection performance of the coatings.
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Qiqi Zhang, Weijun Zhen, Quansheng Ou, Yusufu Abulajiang and Gangshan Ma
The objective was to investigate the utility of cottonseed oil (CSO) as a raw material for the synthesis of CSO water-based alkyd resin. The synthesis involved the polymerization…
Abstract
Purpose
The objective was to investigate the utility of cottonseed oil (CSO) as a raw material for the synthesis of CSO water-based alkyd resin. The synthesis involved the polymerization of CSO, trimethylolpropane, phthalic anhydride (PA) and trimellitic anhydride (TMA). The prepared resin coating material was subsequently applied to the surface of steel structure material.
Design/methodology/approach
This study aimed to synthesize water-based alkyd resins using CSO. Therefore, the alkyd resin was introduced with TMA containing carboxyl groups and neutralized with triethylamine (TEA) to form a water-soluble salt. Then, the esterification kinetics of CSO water-based alkyd resin were investigated, and finally, the basic properties of CSO water-based alkyd resin coating were evaluated.
Findings
It was demonstrated that CSO water-based alkyd resin exhibited excellent water solubility and that the esterification kinetic of the synthesis reaction could be described by a second-order reaction. The coating properties of the material were investigated and found to have good basic properties, with 40% resin addition having the best corrosion resistance. Consequently, it could be effectively applied to the surface of steel structural materials.
Originality/value
This study not only met the requirement of environmentally friendly development but also expanded the application of CSO through the synthesis of CSO water-based alkyd resin via alcoholysis. Compared to fatty acid process, the alcoholysis reduced the need for fatty acid pre-extraction, simplifying the alkyd resin synthesis process. Thus, economic costs are effectively reduced.
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Yingjun Zhang, Xue-Jun Cui, Yawei Shao, Yanqiu Wang, Guozhe Meng, Xiu-Zhou Lin, Dongquan Zhong and Dajian Wang
This paper aims to prepare a residual rust epoxy coating by adding different quantities of phytic acid (PA) on the surface of the rusty steel and investigate the corrosion…
Abstract
Purpose
This paper aims to prepare a residual rust epoxy coating by adding different quantities of phytic acid (PA) on the surface of the rusty steel and investigate the corrosion protection of PA and its action mechanisms.
Design/methodology/approach
A residual rust epoxy coating by adding different quantities of PA was prepared on the surface of the rusty steel. The influence of PA on the corrosion resistance of epoxy-coated rusty steel was investigated by means of electrochemical impedance spectroscopy and adhesion testing.
Findings
Results indicated that PA can substantially improve the corrosion resistance of epoxy-coated rusty steel. This improvement is due to the reaction of PA with residual rust and generation of new compounds with protection properties and increased adhesive strength effects on the coating/metal interface. The coating showed better protection performance when 2 per cent PA was added.
Originality/value
Considering the structure of the active groups, PA has strong chelating capability with many metal ions and can form stable complex compounds on the surface of a metal substrate, thereby improving corrosion resistance. In recent years, PA has been reported to be useful in the conversion of coatings or as green corrosion inhibitor. To the best of the authors’ knowledge, few studies have reported the use of PA as a rust converter or residual rust coating. The present work aims to improve the corrosion resistance of residual rust epoxy coating by adding PA.
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Khalid Abdalla and Hussain Zuhailawati
The purpose of this paper is to study the effect of different concentrations of pretreatment solution of copper acetate (1, 5 and 10 g/L) on the deposition, growth and protection…
Abstract
Purpose
The purpose of this paper is to study the effect of different concentrations of pretreatment solution of copper acetate (1, 5 and 10 g/L) on the deposition, growth and protection ability of zinc phosphate coating.
Design/methodology/approach
Zinc phosphate coatings were deposited on steel surface by immersion method. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to study the morphological evolution and chemical analysis of formed coatings. The electrochemical performance of the coatings was evaluated via potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and immersion test in an aerated 3.5% NaCl solution.
Findings
The results showed that the activation treatment accelerated the deposition of the phosphate coating and improved its surface coverage. A higher phosphate coating weight (7.35 g/m2) and more compact structure was obtained with pretreatment solution of 1 g/L copper acetate. Electrochemical results revealed that the protection ability of the phosphated substrates was markedly enhanced after the pretreatment, and the best corrosion protection was obtained with a concentration of 1 g/L copper acetate solution. The corrosion current density of phosphated substrate was reduced by 64.9% after activation treatment with 1 g/L copper acetate solution.
Originality/value
In this investigation, dense, stable and compact zinc phosphate layers with improved corrosion resistance were formed on a carbon steel surface after activation pretreatment with copper acetate solution prior to a phosphating step.
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Oriana D'Alessandro, Christian Eduardo Byrne, Gonzalo Selmi and Cecilia Deyá
This paper aims to formulate and prepare a series of alkyd paints with new anticorrosive pigments, eco-friendly to the environment, based on a natural zeolitic rock modified by…
Abstract
Purpose
This paper aims to formulate and prepare a series of alkyd paints with new anticorrosive pigments, eco-friendly to the environment, based on a natural zeolitic rock modified by ion exchange to incorporate passivating cations.
Design/methodology/approach
The electrochemical characterization of the painted steel was carried out by conductivity measurements, linear polarization tests, measurements of the corrosion potential and electrochemical noise measurements. Besides, accelerated tests in standard environmental chambers were also carried out.
Findings
The results show that clinoptilolite–mordenite-based pigments incorporated in the paint provide acceptable anticorrosive properties, taking into account their low environmental impact and the use of a natural resource of low cost. The inhibitory efficiency of ZLa is higher than 80% and of ZPr is close to 70%. The electrochemical assays of the coated panels with the alkyd paints ZLa and ZPr shows similar behavior.
Research limitations/implications
In this work, good results were obtained with an alkyd resin, but other resins could be tested. Paints could also be formulated with modified zeolites as a complement to others traditional anticorrosive pigments.
Practical implications
These paints could be used for the protection of metal structures in low corrosive environments.
Originality/value
There are not many published works using zeolites as anticorrosive pigments.
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Giuseppe Moretti, Francesca Guidi, Roberto Canton, Marino Battagliarin and Gilberto Rossetto
To evaluate the corrosion performance and nano‐mechanical behaviour of a brass substrate covered by different thick SiO2 layers deposited by means of plasma enhanced chemical…
Abstract
Purpose
To evaluate the corrosion performance and nano‐mechanical behaviour of a brass substrate covered by different thick SiO2 layers deposited by means of plasma enhanced chemical vapour deposition (PECVD) technique.
Design/methodology/approach
The comparison between laboratory and “industrial” objects revealed a very good corrosion behaviour and good mechanical performance of both of them: in particular it was possible to modulate the surface treatment to solve various problems from the industrial point of view.
Findings
It was possible to reduce the Cu migration into the SiO2 coating during the PECVD deposition at a negligible level and to control it by the deposition; further, the nano‐indentation tests revealed the great utility of the coating annealing in obtaining a significant improvement of the mechanical properties of the coated objects.
Research limitations/implications
Even if some industrial problems were solved (minimization of the presence of the coating defects and transparency of the coatings), some on the layer hardness (anti‐wear behaviour of the industrial objects) has to be better investigated and possibly solved.
Practical implications
The work reports a deposition process that is carried out industrially over a two year period.
Originality/value
This research reports a PECVD process realized on industrial objects: the originality is in the reached corrosion and mechanical performances that made it possible to realize a satisfactory industrial deposition.