Comparative corrosion testing of eight systems of electrodeposited protective-decorative Ni/Cr and Cu/Ni/Cr coatings on steel II: Field tests

Biestek, Tadeusz

doi:10.1016/0376-4583(84)90091-8

Cited by 2 publications

(1 citation statement)

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“…Os estudos que relatam a busca de alternativas para as camadas de conversão de cromato foram intensificados pelas restrições e até mesmo proibição do uso de cromo hexavalente. Estas investigações começaram com os metais oxiânicos por apresentarem algumas características semelhantes ao cromo e menor toxicidade e, posteriormente, por elementos adjacentes na tabela periódica, como vanádio e manganês utilizados na forma de seus sais (BIESTEK, 1984;GIGANDET, 1997;XIA, 2000).…”

Section: Introductionunclassified

Modificação da superfície de aço eletrozincado para proteção contra a corrosão por revestimentos isentos de cromo

Júnior¹,

José²

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Electrogalvanized coatings are employed as active galvanic protection to steel and its applications have been used industrially for a long time. However, as zinc is a very reactive element, the treatment of the surface is necessary to increase its lifespan. The most common treatment consisted of a conversion treatment in solution containing hexavalent chromium, which has been banned by generating toxic and carcinogenic substances, and its use prohibited by European standards. In this work, surface treatments alternative to chromating for electrogalvanized steel that do not generate toxic waste were studied. The chosen treatment was developed in stages. The first stage involved the use of an organic compound, 2 butyne 1,4 diol propoxylate in solution with oxidizing salts and cerium nitrate as an additive. The next step involved immersing the treated surface by the previous step in an oxidizing agent, hydrogen peroxide. The third step consisted of immersion in solution with 2-butyne 1,4 diol propoxylate and ammonium niobium oxalate (ANO). Treated surfaces after each step were characterized by optical microscopy and scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and photoelectron spectroscopy X-ray (XPS). The characterization for corrosion of the treated surfaces was made by salt spray tests and electrochemical impedance spectroscopy (EIS). The results showed that each step has a contribution in increasing the corrosion resistance and this was dependent on the treatment time adopted in each of the three stages. The chemical composition of the layers obtained was characterized by FTIR and XPS. This last technique allowed to analyze the distribution of the elements in the layer formed along its thickness, by sputtering the surface to obtain depth profiling. The presence of carboxylic acid bonded to the metal substrate (zinc) was observed. The results showed that there was formation of organic layer and the incorporation of cerium and niobium this layer. These elements were distributed throughout the length of the layer in the form of oxides in two oxidation states; in the case of cerium, as III and IV, and IV and V, in the case of niobium. The layers formed after the various steps contain a polymeric structure and a mixture of oxides/hydroxide, particularly of zinc, which are retained in the structure of the layer and provide corrosion protection to the metal substrate for prolonged periods. The corrosion results showed that the best treatment (T10_10_10) provided protection to the substrate for long periods of time and that was higher compared to that promoted by the chromate layer, either by the salt spray test as the EIS test. Therefore, this treatment proved a promising replacement to chromate layer in the corrosion protection of electrogalvanised steel, either from its corrosion properties or from an environmental point of view.

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Section: Introductionunclassified

Modificação da superfície de aço eletrozincado para proteção contra a corrosão por revestimentos isentos de cromo

Júnior¹,

José²

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show abstract

Comparative corrosion testing of eight systems of electrodeposited protective-decorative Ni/Cr and Cu/Ni/Cr coatings on steel I: Accelerated laboratory corrosion tests

Biestek

1984

Surface Technology

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Comparative corrosion testing of eight systems of electrodeposited protective-decorative Ni/Cr and Cu/Ni/Cr coatings on steel II: Field tests

Cited by 2 publications

References 1 publication

Modificação da superfície de aço eletrozincado para proteção contra a corrosão por revestimentos isentos de cromo

Modificação da superfície de aço eletrozincado para proteção contra a corrosão por revestimentos isentos de cromo

Comparative corrosion testing of eight systems of electrodeposited protective-decorative Ni/Cr and Cu/Ni/Cr coatings on steel I: Accelerated laboratory corrosion tests

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