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Article

A. Kalendová and J. Brodinová

The development of new protective organic coatings is affected by a number of factors, the most important ones at present being those related to environmental…

Abstract

The development of new protective organic coatings is affected by a number of factors, the most important ones at present being those related to environmental acceptability of anticorrosive pigments. An effective solution has been shown to be the application of anticorrosive inorganic pigments based on mixed metal oxides. These pigments consist of spinel and rutile lattice structures. In order to examine the anticorrosive properties, the individual pigments prepared were added to alkyd and styrene‐acrylate based test coatings. Both the anticorrosion efficiencies, and the mechanisms of action of the pigments were also evaluated.

Details

Anti-Corrosion Methods and Materials, vol. 50 no. 5
Type: Research Article
ISSN: 0003-5599

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Article

M. Deyá, V.F. Vetere, R. Romagnoli and B. del Amo

The efficiency of two anticorrosive pigments containing aluminium polyphosphate was studied. Pigments were analysed by current analytical techniques and characterised by…

Abstract

The efficiency of two anticorrosive pigments containing aluminium polyphosphate was studied. Pigments were analysed by current analytical techniques and characterised by FT‐IR spectrometry. The anticorrosive properties of the selected pigments were evaluated following the electrochemical behaviour of a steel electrode in pigments suspensions. In a second stage, solvent‐borne paints with 30 and 10% v/v of the pigment and PVC/CPVC (pigment volume concentration/critical pigment volume concentration) ratio 0.8 were formulated. Three resins were chosen as film forming materials: an alkyd, an epoxy and a vinyl. The performance of the resulting anticorrosive paints was assessed by accelerated (salt spray cabinet and humidity chamber) and electrochemical tests (corrosion potential, ionic resistance and polarisation resistance). The anticorrosive performance of the tested paints was closely related with pigment composition. The nature of the resin was also of importance; in this sense, epoxy paints showed the best anticorrosive performance. Good correlation has been obtained between accelerated and electrochemical tests.

Details

Pigment & Resin Technology, vol. 30 no. 1
Type: Research Article
ISSN: 0369-9420

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Article

H.S. Emira and F.F. Abdel‐Mohsen

Magnesium ferrite pigments were evaluated as active pigments in anticorrosive water‐borne paints. The study includes the use of two different anticorrosive pigment volume…

Abstract

Magnesium ferrite pigments were evaluated as active pigments in anticorrosive water‐borne paints. The study includes the use of two different anticorrosive pigment volume concentration (APVC), 15 and 25 per cent and fixed the Q value (the pigment volume concentration/critical pigment volume concentration ratio) in both paint formulations. Epoxy and acrylated alkyd resins were used as binders. The paints were evaluated by accelerated salt spray tests, corrosion tests in condensed water and sulphur dioxide chambers and electrochemical evaluations. The results obtained were compared with reference paints containing zinc ferrite and zinc phosphate pigments. Ferrite pigments passivate the carbon steel directly in the case of neutral epoxy resin binder or indirectly due to the soaps produced as a result of reaction with the acidic acrylated alkyd resin binder. A lower per cent, i.e. 15 per cent of APVC was found to be sufficient to provide satisfactory anticorrosion protection.

Details

Pigment & Resin Technology, vol. 32 no. 4
Type: Research Article
ISSN: 0369-9420

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Article

Nivin M. Ahmed, Hassan S. Emira and Hesham M. Tawfik

Ion‐exchange clays containing sodium such as bentonite and montmorillonite have the ability to exchange their cations. Few studies conducted with this type of ion‐exchange…

Abstract

Purpose

Ion‐exchange clays containing sodium such as bentonite and montmorillonite have the ability to exchange their cations. Few studies conducted with this type of ion‐exchange pigments are not conclusive about their anticorrosive efficiency. The present research aims to address the study on the anticorrosive efficiency of this type of pigments in chlorinated rubber paints. Sodium‐bentonite was exchanged with Zn, Sr and Zn‐Sr to be applied on low carbon steel specimens and study the anticorrosive performances of these new ion‐exchanged bentonites (IEBs) in anticorrosive paint formulations.

Design/methodology/approach

The new pigments were characterised using scanning electron microscopy (SEM) and X‐ray fluorescence (XRF) to determine the CEC (cation exchange capacity) of the different exchanged cations. Evaluation of the ion‐exchanged and Na‐bentonite pigments using international standard testing methods (ASTM) was estimated. Paint systems manufactured with these ion‐exchange pigments have been subjected to adhesion, accelerated corrosion laboratory tests, and EIS in order to assess their anticorrosive behaviour.

Findings

The results of this work revealed that the ion‐exchange bentonite (IEBs) pigments showed high anticorrosive performance that can be arranged as follows: Sr‐bentonite was better than Zn‐Bentonite and both were better than the double Zn‐Sr‐bentonite indicating an antagonism behaviour between the two cations when present together.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent and fillers.

Originality/value

These prepared pigments are environmentally friendly pigments which impart high anticorrosive behaviour to paint films with great economic savings.

Details

Pigment & Resin Technology, vol. 42 no. 3
Type: Research Article
ISSN: 0369-9420

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Article

Nivin M. Ahmed, Mostafa G. Mohamed, Reham H. Tammam and Mohamed R. Mabrouk

This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent…

Abstract

Purpose

This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed.

Design/methodology/approach

Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments.

Findings

The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture.

Originality/value

Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

Details

Pigment & Resin Technology, vol. 47 no. 4
Type: Research Article
ISSN: 0369-9420

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Article

Nivin M. Ahmed and Mohamed M. Selim

The purpose of this paper is to determine a new easy route to obtain high performance and economic anticorrosive hybrid pigments based on kaolin and ferrite. The new route…

Abstract

Purpose

The purpose of this paper is to determine a new easy route to obtain high performance and economic anticorrosive hybrid pigments based on kaolin and ferrite. The new route is based on depositing a surface layer of an expensive efficient anticorrosive pigment (ferrite) on a bulk of cheap extender pigment (kaolin). The combination of these pigments can add improved properties to the new pigment different from each of its individual components. These improved properties lead to imparting new properties to paint films containing these prepared pigments.

Design/methodology/approach

The new prepared hybrid pigments contain different concentrations of deposited ferrite on kaolin surface, are determined using X‐ray fluorescence analysis to estimate the concentration of each element in the pigments. The pigments are characterised using different spectro‐photometric and analytical methods to prove the deposition of the shell layer and elucidate the structure of their particles. Then, they are incorporated in anticorrosive paint formulations, where their presence in these formulations is between 50 and 75 per cent of the total pigments in the paint formula. A model of the mechanism of protection to the metal substrate is presented.

Findings

The results show that the presence of these hybrid pigments imparts excellent corrosion protection to steel substrates, in spite of their different concentrations and loadings in the paint films.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as filler and reinforcing agent.

Originality/value

Prepared pigments are eco‐friendly and can replace other hazardous pigments (e.g. chromates) – also it can replace original ferrite pigments. These pigments can compensate for the presence of other known pigments in markets successfully. The main advantage of these pigments is that they combine both the properties of their counter‐parts, and they are of lower cost than the original inhibitive pigment (ferrite). Also, they can be applied in other industries other than paints, e.g. paper, rubber and plastics composites.

Details

Pigment & Resin Technology, vol. 39 no. 2
Type: Research Article
ISSN: 0369-9420

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Article

A. Kalendová, D. Veselý and J. Brodinová

The spinel‐type pigments of a general formula corresponding to AB2O4 containing as A the Mg2+ or Zn2+ ions and as B the Fe3+ or Al3+ ions or combinations of both the A and…

Abstract

The spinel‐type pigments of a general formula corresponding to AB2O4 containing as A the Mg2+ or Zn2+ ions and as B the Fe3+ or Al3+ ions or combinations of both the A and B were prepared and investigated with respect to their anticorrosive action as pigments in organic coatings. For the same purposes, comparative pigments, known for their efficiency as the metal‐corrosion inhibiting ingredients in similar formulations, were used. Further evaluation was carried out on the properties of condensed phosphates as anticorrosion pigments. The results obtained showed the high anticorrosion action of the spinel‐type pigments.

Details

Anti-Corrosion Methods and Materials, vol. 51 no. 1
Type: Research Article
ISSN: 0003-5599

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Article

Mayya Ziganshina, Sergey Stepin, Sergey Karandashov and Veronika Mendelson

The purpose of this paper is to search for toxic anticorrosive pigments’ substitute in protective coatings is one of the important tasks that the specialists in the field…

Abstract

Purpose

The purpose of this paper is to search for toxic anticorrosive pigments’ substitute in protective coatings is one of the important tasks that the specialists in the field of steel corrosion face.

Design/methodology/approach

One of the ways to solve the problem of metal corrosion is to use complex oxides as pigments, which are characterized as low-toxic compounds and possess the ability to inhibit corrosion.

Findings

In the production of ferrites, it is possible to use production waste as raw material, and that makes it possible to reduce the price of the resulting product and solve environmental problems simultaneously.

Originality/value

Permanent growth of world production is accompanied by the increasing environment corrosiveness, associated with the intensification of air, water basin and soil pollution by industrial waste. This, as well as the continuously increasing operated metal stock, has recently made the tendency of metals’ total loss from corrosion steadily increasing. All of this points to the importance of studying corrosion processes and the systematic and effective fight against metal corrosion.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 4
Type: Research Article
ISSN: 0003-5599

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Article

Nivin M. Ahmed, Walaa M. Abd El-Gawad, Elham A. Youssef and Eglal M. Souaya

The purpose of this work is to prepare new core-shell pigments based on silca fume waste as core and ferrite pigments in the shell. Silica fume is a byproduct of the…

Abstract

Purpose

The purpose of this work is to prepare new core-shell pigments based on silca fume waste as core and ferrite pigments in the shell. Silica fume is a byproduct of the smelting process in the ferrosilicon industry. The reduction of high-purity quartz to silicon at temperatures up to 2,000°C produces SiO2 vapours which then oxidize and condense at low-temperature zones to tonnage amounts of tiny particles consisting of non-crystalline silica that is collected and sold rather than being land-filled because nowadays there is increasing environmental concern with regard to excessive volumes of solid waste hazards accumulation. Silica has no direct effect in protecting metals from corrosion, but on precipitating an effective anticorrosive pigment like ferrite on its surface with low concentrations, this can bring out new core-shell pigment with good anticorrosive performance and low cost. The new pigments will be constructed on a waste silica fume core comprising 80-85 per cent of its chemical structure and the ferrite shell that will be only about 20-15 per cent. These pigments are represented as efficient, economically feasible and eco-friendly.

Design/methodology/approach

The different ferrites and ferrites/SiO2 pigments were characterized using different analytical and spectro-photometric techniques, such as X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray and transmission electron microscopy (TEM). Evaluation of these pigments was done using international standard testing methods american standard testing methods (ASTM). After evaluation, the pigments were incorporated in solvent-based paint formulations based on medium oil-modified soya-bean-dehydrated castor oil alkyd resin. The physico-mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5 per cent sodium chloride for 28 days were determined.

Findings

The results of this work revealed that ferrite/SiO2 core-shell pigments were close in their performance to that of the ferrite pigments in protection of steel, and at the same time, they verified good physico-mechanical properties.

Practical implications

As silica fume has a large array of uses, these pigments can be applied in various industries such as painting, wooding coating, anti-corruption coating, powder coating, architectural paint and waterproof paints.

Originality/value

Ferrite, ferrite/SiO2 are environmentally friendly pigments which can impart high anticorrosive behaviour to paint films with concomitant cost savings.

Details

Pigment & Resin Technology, vol. 43 no. 4
Type: Research Article
ISSN: 0369-9420

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Article

H.S. Emira

To develop a method for the preparation of micaceous zinc ferrite (MZF), anticorrosive pigment having desirable chemical and physical properties.

Abstract

Purpose

To develop a method for the preparation of micaceous zinc ferrite (MZF), anticorrosive pigment having desirable chemical and physical properties.

Design/methodology/approach

MZF pigment was prepared after firing the oxidised solid molten salts without washing. The MZF pigment obtained was characterised using X‐ray diffraction analysis, crystal size analysis, scanning electron microscope and energy dispersive X‐ray analysis. The pigment obtained was also evaluated chemically with respect to moisture content, content of water‐soluble salts, hydrogen ion concentration (pH) and weight loss; and physically with respect to particle shape, colour, specific gravity and oil absorption. Commercially available micaceous iron oxide and zinc ferrite pigments were also characterised in comparison.

Findings

A spinel, MZF pigment was prepared using relevant oxidised solid molten salts. The preparation produced a lamellar structure with a basic nature giving not only barrier protection but also chemical passivation of the substrate.

Research limitations/implications

The anticorrosive properties of the pigments obtained could be evaluated using more conventional methods such as salt‐spray test.

Practical implications

The pigment prepared could be used as a highly efficient pigment for anticorrosion coating for steel.

Originality/value

The method for the preparation of MZF pigment was novel. The pigment obtained could be used in various resin systems to produce anticorrosive paints for steel protection.

Details

Pigment & Resin Technology, vol. 34 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

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