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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A. Kalendová, D. Veselý and P. Kalenda
The purpose of this paper is to synthesise X2TiO4 spinel‐type anticorrosion pigments and YTiO3, perovskite‐type anticorrosion pigments, where X = Zn, Mg, Ca, Sr; Y = Ca for metal…
Abstract
Purpose
The purpose of this paper is to synthesise X2TiO4 spinel‐type anticorrosion pigments and YTiO3, perovskite‐type anticorrosion pigments, where X = Zn, Mg, Ca, Sr; Y = Ca for metal protective paints.
Design/methodology/approach
Anticorrosion pigments were synthesised from oxides or carbonates at high temperature. The following pigments were synthesised: TiO2 · ZnO, 2TiO2 · ZnO, TiO2 · 2ZnO, TiO2 · MgO, TiO2 · CaO, TiO2 · ZnO · MgO, and TiO2 · ZnO · SrO. The pigments obtained were characterised by means of X‐ray diffraction analysis, measurement of particle sizes and scanning electron microscopy. The anticorrosion pigments synthesised were used to produce epoxy coatings with PVC = 10 per cent for each synthesised pigment. The coatings were tested for physical‐mechanical properties and in corrosion atmospheres. The corrosion test results were compared with those of alumino zinc phosphomolybdate.
Findings
A spinel or perovskite structure was found in the pigments synthesised. High anticorrosion efficiency was identified in all the synthesised pigments, the highest efficiency being demonstrated in the TiO2 · ZnO pigment of spinel structure and in the TiO2 · CaO pigment of perovskite structure.
Practical implications
The pigments synthesised can be conveniently used to protect metal bases from corrosion.
Originality/value
The use of pigments synthesised in anticorrosion coatings for metal protection presents a new approach. Its benefits are the use and the method of synthesising the anticorrosion pigments that do not contain heavy metals and that are acceptable for the environment.
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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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The purpose of this paper is to report salt spray testing of epoxy‐polyester top‐coating applied on Zn‐sprayed, Al‐sprayed and 85Zn‐15Al‐sprayed steel samples.
Abstract
Purpose
The purpose of this paper is to report salt spray testing of epoxy‐polyester top‐coating applied on Zn‐sprayed, Al‐sprayed and 85Zn‐15Al‐sprayed steel samples.
Design/methodology/approach
In these tests, steel substrates sprayed with Zn, Al and 85Zn‐15Al coatings of different average thicknesses ranging from 120 to 210 μm were top‐coated with an epoxy‐polyester sealing layer. The corrosion test was performed with salt solution for over 2,000‐h. The degree of damage to the samples was evaluated quantitatively in terms of ratio of scribed to unscribed area of coating.
Findings
It was evident that the corrosion resistance of Al‐sprayed top‐coated surfaces was better than coated Zn‐spray or coated 85Zn‐15Al‐spray systems. As a result, when Al‐coated surfaces were top‐coated with polymeric layer, it was found that their surfaces were remarkably unaffected by the salt spray environment.
Originality/value
The salt spray measurements indicated that the Al‐spray epoxy‐polyester polymer double system was more durable than the other two systems (polymeric top‐coated Zn‐spay, and polymeric top‐coated 85Zn‐15Al‐spray), so far as protection from the chloride salt spray environment was concerned.
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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.
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Tingyi Chen, Yaqi Ma, Hongtao Zhu and Qiming Huang
The purpose of this study is to prepare trivalent chromium conversion (TCC) film on the Zn-Ni electrodeposited film on the surface of 2024 aluminum alloy and to ensure that the…
Abstract
Purpose
The purpose of this study is to prepare trivalent chromium conversion (TCC) film on the Zn-Ni electrodeposited film on the surface of 2024 aluminum alloy and to ensure that the TCC film has good corrosion resistance and electrical conductivity.
Design/methodology/approach
The morphology of the TCC film was studied by scanning electron microscopy, and the elemental composition of the TCC film was characterized by X-ray energy dispersive spectroscopy. The TCC film was tested and the roughness was analyzed by 3D morphology (white light interference). The electrochemical behavior and corrosion resistance of TCC films were studied by the Tafel polarization curve and electrochemical impedance spectroscopy, and the conductivity was tested.
Findings
The TCC films were uniformly black and bright in appearance and were mainly compounds of Zn, Ni and Cr with O. The electrochemical impedance of the TCC film is larger than that of the Zn-Ni film, the corrosion current (Icorr) is smaller than that of the Zn-Ni film and the corrosion potential (Ecorr) is larger than that of the Zn-Ni film, which has excellent corrosion resistance. TCCs were performed on the appropriate size of the shell sample, and the resistance of the shells was 1.5 mVDC, which meets the total resistance requirements of the test standard for composite connector accessories.
Originality/value
In this study, TCC film was successfully prepared on the Zn-Ni coating on the surface of 2024 aluminum alloy. The TCC film has good corrosion resistance and electrical conductivity.
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P. Kalenda, A. Kalendová and D. Veselý
To identify the dependence of the anticorrosion efficiency of chemically varying pigments on their concentration in steel protecting paints.
Abstract
Purpose
To identify the dependence of the anticorrosion efficiency of chemically varying pigments on their concentration in steel protecting paints.
Design/methodology/approach
Anticorrosion pigments from a group of nontoxic substances were chosen and compared with a chromate pigment. With all pigments, the following parameters were observed namely, oil absorption, critical pigment volume concentration value, density, extract pH, specific surface, particle size, water‐borne substances content, and the specific electrical conductivity of pigment extracts. The aqueous extracts of pigments were used to determine the corrosion loss of steel. The morphology of pigment particles was observed by means of an electron‐scanning microscope. Paints containing these pigments were formulated on the binder basis of an epoxy resin. The paints prepared were subjected to measurement of physical‐mechanical properties such as hardness and resistance in deep drawing. Paints containing anticorrosion pigments were subjected to corrosion tests in a SO2 condenser chamber, salt spray cabinet and to a test according to Machu and Schiffman.
Findings
The experimental investigations revealed the absolute values of the anticorrosion effects of individual pigments as well as dependence of efficiency on the concentration of the pigments in the paints. It was found that environment‐friendly pigments achieved comparable or even better anticorrosion efficiency than toxic strontium chromate.
Research limitations/implications
The anticorrosion properties of the paints concerned can be tested in paints by means of atmospheric exposure such as the Florida test.
Practical implications
The results find their application in the formulation of anticorrosion paints for industrial applications with environment‐friendly effects.
Originality/value
This research paper presents the results of the anticorrosion effects of a great number of industrially used pigments. Based on this paper, the formulation of highly effective steel‐protecting paints can be optimised.
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Ioannis A Kartsonakis, Elias P. Koumoulos, Antonis Karantonis, Costas A. Charitidis, S Dessypris and A Monos
The purpose of this paper is to perform the evaluation of copper susceptibility to corrosion in industrial cooling systems. Microstructure and defects of copper are observed…
Abstract
Purpose
The purpose of this paper is to perform the evaluation of copper susceptibility to corrosion in industrial cooling systems. Microstructure and defects of copper are observed, while divergences from optimum structure are discussed.
Design/methodology/approach
Various types of corrosion are examined. Electrochemical techniques such as electrochemical impedance spectroscopy and potentiodynamic polarisation are applied in these materials, using corrosion inhibitors. Microscopic observations and electrochemical measurements are interpreted according to possible mechanistic scenarios.
Findings
It is evident that, under specific conditions (e.g. high pH), water cooling ingredients can enhance corrosion, leading to significant copper mass loss from the inner surface of the pipe and thus leading to failure.
Originality/value
Evaluation of copper corrosion in cooling industrial systems was done, as well as studies of copper corrosion in sodium chloride.