A. Kalendová

Effects of particle sizes and shapes of zinc metal on the properties of anticorrosive coatings

The paper deals with a study of the zinc particle sizes and shape effects on the anticorrosive coating properties. As a binder the epoxyester resin is used. The zinc particle size and shape effects are discussed from the mechanical coating properties, film permeabilities to water vapor and above all the pigment anticorrosion protection efficiency points of view. The connection between the spherical particle sizes and the coating anticorrosive efficiency was found. The smaller particle sizes mean better anticorrosive coating properties. The lamellar zinc particles exhibit the highest anticorrosion efficiency at a concentration around 20 vol.%.

Alkalising and neutralising effects of anticorrosive pigments containing Zn, Mg, Ca, and Sr cations

The present paper deals with the possibility of replacing toxic anticorrosive pigments with pigments acceptable from the point of view of environment protection. Spinel pigments containing Zn(II), Ca(II), Mg(II), Sr(II), Fe(III), Al(III), and Ti(IV) cations were synthesised. Combining these elements gave five various oxide groups, which were applied to alkyd, styrene-acrylate, epoxy-resin and chlorinated-rubber binders. The binder containing acid groups gave aqueous extract with better inhibitive properties than the non-reactive binders. Using spinel pigments allows to significantly inhibit the corrosion reaction in comparison with the corrosion running in pure water. The chemical composition of synthesised pigments clearly shows that the compounds are ecologically harmless.

A study of the effects of pigments and fillers on the properties of anticorrosive paints

Purpose – To investigate the properties of coatings containing various types of fillers from the point of view of their physical‐mechanical properties and anticorrosive properties.Design/methodology/approach – Research used fillers of different types varying in morphology and/or chemical composition; these were then compared with selected pigments and zinc phosphate, an anticorrosive pigment. The following parameters were observed for all of the fillers and pigments: oil absorption, CPVC value, density, extract pH, specific surface, particle size, and water‐soluble substances. The morphology of particles was observed by means of an electron‐scanning microscope. The coatings of these fillers and pigments were formulated on an epoxy resin binder basis cured with a polyamine hardener. The coatings prepared were subjected to the measurement of physical‐mechanical properties such as hardness and deepening resistance, flex resistance, adhesion to steel, and the gloss of the coatings. The coatings containing the...

Properties of anticorrosion pigments depending on their chemical composition and PVC value

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 ...

Anticorrosive spinel‐type pigments of the mixed metal oxides compared to metal polyphosphates

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.

Anticorrosive spinel‐type pigments of the second generation

The spinels are non‐toxic anticorrosive pigments suitable for both solvent‐type and water‐dilutable coating compositions. Their efficiency in the coatings is comparable to that of the phosphate‐based pigments. The high‐temperature synthesis procedure running in the solid state allows the preparation of spinels containing Ca, Zn, Mg, and Fe cations.

Nontoxic anticorrosion pigments of the spinel type compared with condensed phosphates

The spinel-type compounds of a general formula corresponding to AB2O4 containing as A the ions Mg2+ or Zn2+ and as B the ions Fe3+ or Al3+ or combination of both the A and B given were prepared and investigated with respect to their anticorrosive activities as pigments used in organic coatings. For comparative purposes pigments known for their efficiency as metal-corrosion-inhibiting ingredients in similar formulations were used. Condensed phosphates were also evaluated as anticorrosion pigments. The results obtained shown high anticorrosion activities of the spinel-type pigments.

Anticorrosion properties of SrO–ZnO–B2O3–P2O5 pigments

Seven compositions of anticorrosion pigments of zinc‐strontium borophosphates were prepared and then characterized by X-ray diAraction analysis, solubility measurements, particle size distribution, and the pH of their aqueous extracts. The pigments were dispersed in an alkyd resin formulation, and used in paints. Following application of the paints to steel sheets, they were subjected to standard anticorrosion tests, to assess their anticorrosive‐inhibitory properties. Test results showed that 14.6SrO‐43.7ZnO‐8.3B2O3‐33.3P2O5 and 37.5SrO‐37.5ZnO‐25B2O3 compositions surpassed the anticorrosive properties of standard pigments based on zinc orthophosphate and calcium metaborate. # 2000 Elsevier Science Ltd. All rights reserved.

Comparison of the anticorrosion efficiencies of pigments based on condensed phosphates and polyphosphosilicates

The paper deals with studying the anticorrosive properties of condensed phosphates and polyphosphates in the coatings. The pigments contain cation in the most cases as aluminium in a combination with zinc, strontium, calcium or a combination with all the cations. The investigated anticorrosive pigments differ in water solubility, inhibition efficiencies of their aqueous extracts and also the efficiencies in the coatings protecting steel substrate to corrosion. Two types of condensed anticorrosive pigments (polyphosphates and polyphosphosilicates) were compared. The anticorrosion properties of polyphosphosilicates are inferior to those of polyphosphates. The high anticorrosion efficiency was found at a comparative pigment, represented by zinc phosphosilicate.

Needle‐shaped anticorrosion pigments based on the ferrites of zinc, calcium and magnesium

Purpose – This paper seeks to synthesize needle‐shaped anticorrosion pigments based on the ferrites of Zn, Ca and Mg for metal protecting paints.Design/methodology/approach – Anticorrosion pigments were synthesized from oxides or carbonates at hot temperatures. The following pigments were synthesized: ZnFe2O4, MgFe2O4, CaFe2O4, Mg0.2Zn0.8Fe2O4, and Ca0.2Zn0.8Fe2O4. The prepared pigments were characterized by means of X‐ray diffraction analysis, by measuring the distribution of particle size and by means of scanning electron microscopy. The synthesized anticorrosion pigments were used to formulate epoxy coatings with PVC = 10 per cent for the synthesized pigment and with the PVC/CPVC ratio = 0.3. The coatings were tested for physical‐mechanical properties and in corrosion atmospheres. The corrosion test results were compared with aluminium zinc phosphomolybdate.Findings – The needle‐shaped particles were identified in the formulated pigments. It was found that all of the synthesized pigments had high antic...