Anales CIDEPINT 1997-98
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Examinando Anales CIDEPINT 1997-98 por Autor "del Amo, Beatriz"
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Acceso Abierto High performance anticorrosive epoxy paints pigmented with zinc molybdenum phosphate(1998) Romagnoli, Roberto; del Amo, Beatriz; Vetere, Vicente; Véleva, L.Zinc molybdenum phosphate belongs to the so called second generation phosphate pigments and is claimed to have equal or greater anticorrosive properties than chromates and better than zinc phosphate alone. Little Information is available in the literature about its anticorrosive performance. The aim of this research was to stucfy the anticorrosive performance of zinc molybdenum phosphate in solvent borne epoxy paints employing two anticorrosive pigment loadings. The effect of incorporating zinc oxide as complemetary pigment was also studied SAE 1010 Steel ponéis were primed and coated with three different paint systems containing the anticorrosive paint and this paint plus a sealer cmd/or a topcoat. The anticorrosive efftciency of the different paint systems was assessed by accelerated tests (salí spray, humidity and accelerated weathering). Electrochemical measurements were done employing the anticorrosive paints alone. Results showed that the highest anticorrosive effect was obtained employing 30% of zinc molybdenum phosphate. Polarization measurements showed that the anoche film formed on Steel blocked the active sites for oxygen reduction. The incorporation of zinc oxide to pigment formula was detrimental due to its high water absorption and to the fact that it reduced zinc molybdenum phosphate solubility by the common ion effect. Polarization curves of pigments mixtures could be used as a guideline to precüct the anticorrosive coating performance in accelerated and electrochemical tests. However, the final decisión on pigment selection musí be taken on the basis of accelerated triáis. - Artículo
Acceso Abierto The performance of zinc molybdenum phosphate in anticorrosive paints by accelerated and electrochemical tests(1998) del Amo, Beatriz; Romagnoli, Roberto; Vetere, VicenteRed lead and zinc chromates are doubtless efficient pigments to protect metáis against corrosión. Their use in paints formulation is being restricted due to their deleterious action. Zinc phosphate wasfirstly suggested to replace toxic chromates. However, data on their anticorrosive properties are not conclusive; so, a second generation of phosphate pigments, including zinc molybdenum phosphate, was developed In this paper, the anticorrosive behavior of micronized zinc molybdenum phosphate in paints with 30% of the pigment by volume and a PVC/CPVC ratio 0.8, formulated with different binders (alkyd, vinyl, chlorinated rubber and epoxy resins), was assessed by accelerated (salt spray cábinet and accelerated weathering) and electrochemical tests. Epoxy and chlorinated rubber paints showed the best anticorrosive performance. The inhibitive action of zinc molybdenum phosphate was confirmed Good correlation has been obtained between salt spray and electrochemical tests. - Artículo
Acceso Abierto Steel corrosión protection by means of alkyd paints pigmented with calcium acid phosphate(1998) del Amo, Beatriz; Romagnoli, Roberto; Vetere, VicenteThe use of classic anticorrosive pigments is beirtg more and more restricted by increasing environmental concems; they are gradually replaced by zinc phosphate and related compounds. Other anticorrosive pigments such as surface exchanged silicas were also proposed The object of this research is to study the anticorrosive properties of calcium acid phosphate as inhibitive pigment introducing a careful selection of complementary pigments in order to achieve an efficient anticorrosive protection. Several paints were prepared and tested through accelerated and electrochemical tests. The nature of the passive film was also studied. Paints containing zinc oxide and calcium carbonate (50/50) showed the best performance and a higher resistance in the salí spray test. Zinc oxide and calcium carbonate decreased film permeability and improved Steel passivation The passive film was composed by a ferric oxyhydroxide film whose pores became plugged by ferric phosphate.