Abstract
Owing to present and expected future regulations on the use of polluting antifouling compounds, there is a growing need for alternative methods for the prevention of biofouling. Some experiments on the effect of iron benzoate, as a possible biocide agent, on nauplii of Balanus amphitrite were carried out. This pigment was used because it is rapidly hydrolysed and consequently it produces a pH decrease. Although anion benzoate has an intense narcotic effect on nauplii, the results clearly demonstrated that the combined action of this compound and a pH decrease (generated by iron benzoate hydrolysis) produce a pronounced antifouling activity, i.e. the synergic effect is greater than separate effects.
Details
Keywords
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.
Details
Keywords
Walaa M. Abd El-Gawad, Nivin M. Ahmed, Mohamed M. Selim, E. Hamed and Eglal R. Souaya
In recent years, zeolites have been highlighted as a new component in many industrial applications owing to their unique properties. The purpose of this study is to apply three…
Abstract
Purpose
In recent years, zeolites have been highlighted as a new component in many industrial applications owing to their unique properties. The purpose of this study is to apply three prepared types of zeolites Na-X, Na-Y and hydroxysodalite (Na-HS) in anticorrosive paint formulations to be evaluated as a partial replacement to zinc phosphate in anticorrosive paint formulations to protect carbon steel.
Design/methodology/approach
The three types of zeolites were characterized using different instrumental analysis such as X-ray diffraction, scanning electron microscopy and X-ray fluorescence. Evaluation of zeolites was done using American society for material and testing. Then, they were incorporated in paint formulations based on medium oil-modified soya-bean dehydrated castor oil alkyd resin in the presence and absence of zinc phosphate. Their corrosion behavior was estimated using both immersion test and electrochemical impedance measurements in 3.5% NaCl.
Findings
Generally, the prepared zeolites exhibited good corrosion protection performance, but in presence of zinc phosphate the performance was better. This proves that, zeolites by themselves can resist corrosion but not efficiently, while in presence of zinc phosphate and owing to a synergistic effect between them, the performance was better. This opens the way to partial replacement of zinc phosphate with another safer and cheaper ingredient, which is zeolite.
Practical implications
The three zeolites can be applied in many industries besides the paint industry, such as reinforcing filler in rubber, plastics and ceramic composites, also can be applied in paper filling, paper coatings and electrical insulation.
Originality/value
The three zeolites are environmentally friendly materials that can partially replace other expensive anticorrosive pigments (e.g. zinc phosphate).
Details
Keywords
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.
Details
Keywords
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 FT‐IR…
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.
A. Kalendová, D. Veselý and P. Kalenda
To synthesise calcium titanate with a perovskite structure as an anticorrosion pigment for metal protecting paints.
Abstract
Purpose
To synthesise calcium titanate with a perovskite structure as an anticorrosion pigment for metal protecting paints.
Design/methodology/approach
Calcium titanate was synthesised from titanium dioxide and calcium carbonate at high temperature. The pigment obtained was characterised by means of X‐ray diffraction, particle size distribution measurement and scanning electron microscopy. The pigment obtained was further characterised with regard to the parameters required for paint formulation; its specific mass was determined by oil consumption and critical pigment volume concentration. The synthesised calcium titanate was used to prepare epoxy coatings with varying contents of the anticorrosion pigment. The coating was tested for physical‐mechanical properties and in corrosive atmospheres. The results were compared with titanium dioxide that served as a starting material for calcium titanate preparation.
Findings
Calcium titanate was prepared from materials that do not add any impurities to the anticorrosion properties of the pigment. It was identified that calcium titanate of perovskite structure is a highly efficient anticorrosion pigment for paints.
Practical implications
Calcium titanate can be utilised for the preparation of anticorrosion paints to protect metal bases from corrosion.
Originality/value
The method of synthesising calcium titanate as an anticorrosion pigment is new. The literature has not yet described the use of calcium titanate as a pigment with inhibitive properties in paints. From an ecologic standpoint, the application of a new anticorrosion pigment for paints presents a highly positive trend.
Details
Keywords
Nivin M. Ahmed, Walaa M. Abd El-Gawad, Ahmed A. El_Shami and Eglal M.R. Souaya
This study aims to synthesize a series of new anticorrosive pigments using a new technique called “core-shell”. This technique is based on depositing thin surface layer of…
Abstract
Purpose
This study aims to synthesize a series of new anticorrosive pigments using a new technique called “core-shell”. This technique is based on depositing thin surface layer of expensive, efficient anticorrosive pigment on a cheap extender. This extender forms the bulk of the new pigments. The new pigments were constructed on cores of either waste silica fume or kaolin comprising 80-85 per cent of their chemical structure, and the ferrite shell was about of 20-15 per cent. Electrochemical studies were undertaken on two series of pigments for comparison between ferrites/silica fume and ferrites/kaolin pigment to show their performance, as the shells are different.
Design/methodology/approach
The different ferrites/silica fume and ferrites/kaolin pigments were characterized using different analytical and spectrophotometric techniques, such as X-ray fluorescence (XRF) and transmission electron microscopy (TEM). Immersion test and electrochemical impedance measurements were done in 3.5 per cent NaCl.
Findings
The tests revealed that paint films containing Sr ferrite/silica and Ca ferrite/kaolin were the most effective in corrosion prevention.
Practical implications
Silica fumes have 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. Treated kaolin can be applied in many industries besides pigment manufacture and paint formulations; it can be applied as a reinforcing filler in rubber, plastics and ceramic composites.
Originality/value
The new pigments are considered ecofriendly materials, because using them converts a waste product and a natural ore to useful marketable product, leading to reducing cost and saving the environment at the same time.
Details
Keywords
P. Mošner, D. Veselý, L. Koudelka and A. Kalendová
The purpose of this paper is to synthesise glassy and crystalline Ca‐Zn and Sr‐Zn borophosphates.
Abstract
Purpose
The purpose of this paper is to synthesise glassy and crystalline Ca‐Zn and Sr‐Zn borophosphates.
Design/methodology/approach
Anticorrosion pigments on the basis of glassy and crystalline borophosphates formulated as 20CaO‐30ZnO‐20B2O3‐30P2O5 and 20SrO‐30ZnO‐20B2O3‐30P2O5 were synthesised. The pigments prepared were characterised by means of X‐ray diffraction and their physical‐chemical properties were determined. The pigments synthesised were used to prepare water‐borne styrene‐acrylate coatings with a 10 per cent anticorrosion pigment content. The coatings underwent corrosion tests in a humid environment with SO2 content and a test in a salt mist environment. The corrosion tests results were compared with industrially produced pigments.
Findings
As the glassy phase reduces the anticorrosion efficiency of the coatings with the Sr‐Zn borophosphate content decreases too. In case of the Ca‐Zn borophosphates, the maximum anticorrosion efficiency was detected with regard to a pigment containing 75 wt% of the glassy phase.
Practical implications
The pigments synthesised can be conveniently used in water‐borne coatings to protect metal bases from corrosion.
Originality/value
The application of the synthesised glassy‐crystalline borophosphate pigments in anticorrosion water‐borne coatings to protect metal bases from corrosion presents a new method. The use and the method of synthesising these anticorrosion pigments are beneficial.
Details
Keywords
P. Mošner, A. Kalendova´ and L. Koudelka
Twelve pigment compositions derived from the xCaO·(50−x)ZnO·20B2O3·30P2O5·(x=10, 20, 30) and yMgO·(50−y)ZnO·20B2O3·30P2O5·(y=10, 20, 30) systems were prepared. The synthesis was…
Abstract
Twelve pigment compositions derived from the xCaO·(50−x)ZnO·20B2O3·30P2O5·(x=10, 20, 30) and yMgO·(50−y)ZnO·20B2O3·30P2O5·(y=10, 20, 30) systems were prepared. The synthesis was carried out either by the medium‐temperature process or by the high‐temperature process followed by cooling in air and an isothermal crystallisation of the glass obtained. The pigments prepared by the medium‐temperature process achieved better corrosion results in styrene‐acrylate coating formulations, whereas those prepared by the high‐temperature process achieved better results in alkyd‐resin coating formulations. The anti‐corrosion results for the Ca‐Zn pigments were better than those for the Mg‐Zn pigments.