EIS and microstructural characterization of artificial nitrate patina layers produced at room temperature on copper and bronze

H., R. del P. Bendezú; Gonçalves, Rita; Neiva, A.C.; Melo, Hercílio Gomes de

doi:10.1590/s0103-50532007000100006

Cited by 19 publications

(8 citation statements)

References 25 publications

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“…This patina presents a porous bi-layer structure with a total thickness of about 6.5 m, and the surface is uniformly covered with needle-like crystals. EDS analyses performed on the top layer showed intense peaks of Cu, N and O, while in the internal layer only Cu and Cl peaks were predominantly identified [16]. These peaks have close relation with the patina solution composition and point towards the combination between copper ions and the anions in solution.…”

Section: Methodsmentioning

confidence: 82%

Electrochemical impedance spectroscopy investigation of the electrochemical behaviour of copper coated with artificial patina layers and submitted to wet and dry cycles

Hernández

Aoki

Tribollet

et al. 2011

Electrochimica Acta

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To cite this version:R. del P.B. Hernandez, I.V. Aoki, Bernard Tribollet, Hercilio G. de Melo. Electrochemical impedance spectroscopy investigation of the electrochemical behaviour of copper coated with artificial patina layers and submitted to wet and dry cycles. Electrochimica Acta, Elsevier, 2011, 56 (7), pp.a b s t r a c t Due to rain events historical monuments exposed to the atmosphere are frequently submitted to wet and dry cycles. During drying periods wetness is maintained in some confined regions and the corrosion product layer, generally denominated patinas, builds up and gets thicker. The aim of this study is to use electrochemical impedance spectroscopy (EIS) to investigate the electrochemical behaviour of pure copper coated with two artificial patina layers and submitted either to continuous or to intermittent immersion tests, this latter aiming to simulate wet and dry cycles. The experiments were performed in 0.1 mol dm −3 NaCl solution and in artificial rainwater containing the most significant pollutants of the city of São Paulo. The results of the continuous immersion tests in the NaCl solution have shown that the coated samples behave like a porous electrode with finite pore length. On the other hand, in the intermittent tests a porous electrode response with semi-infinite pore length can be developed. The results were interpreted based on the model of de Levie and a critical comparison with previous interpretations reported in the literature for similar systems is presented.

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Section: Methodsmentioning

confidence: 82%

Electrochemical impedance spectroscopy investigation of the electrochemical behaviour of copper coated with artificial patina layers and submitted to wet and dry cycles

Hernández

Aoki

Tribollet

et al. 2011

Electrochimica Acta

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“…The first capacitive semicircle at high frequency is attributed to the charge-transfer resistance of the electric double layer, and the second capacitive semicircle at low frequency may be attributed to the film of corrosion products formed on specimens' surfaces, indicating a diffusion controlled electrochemical reaction. Those capacitive loops are wide and depressed, which is likely ascribed to the complex composition of alloys [20,21]. There is an augmentation of the impedance of the sample with the increasing of Mg content, which is likely the consequence of different corrosion resistances of corrosion products.…”

Section: Electrochemical Behaviorsmentioning

confidence: 99%

Effects of Mg content on microstructure and electrochemical properties of Zn–Al–Mg alloys

Yao

Tay

Zhu

et al. 2015

Journal of Alloys and Compounds

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“…There is an increase in the roughness, and a layer is formed with some corrosion products adhered to the coating after being exposed to the NaCl solution at 3.5 wt.%. It is also possible to observe the precipitation of electrolyte crystals, especially in the porous areas of the surface and the formation of the protective patina [22], which is characterized by its green color and by an appearance similar to that of fungi produced by moisture. These results agree with the research of Pompo et al [23] and M. M. Sadawy [24], who reported that the corrosion products formed during the process strongly adhere to the surface.…”

Section: Electrochemical Measurementsmentioning

confidence: 99%

The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

2019

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We report the results of the influence of acetylene and oxygen gas pressure on the corrosion resistance of bronze-aluminum coatings deposited on a naval brass substrate by means of the thermal (flame) deposition process. The coatings were characterized by means of scanning electronic microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and transmission electron microscopy (TEM). The corrosion tests were carried out via Tafel and electrochemical impedance spectroscopy (EIS). In addition, some samples were selected in order to investigate heat treatment and its effects on corrosion resistance. The results indicate that changes in the pressure and flow of the gas affects the composition, morphology, and physical properties of the coatings, and these effects have consequences for the behavior of the coatings when they are immersed in corrosion environments. The collision speed of the particles was identified as the most significant factor that influences the properties and the performance of the coating. The gas pressure modified the oxides and the porosity level, which improved the corrosion resistance.Coatings 2019, 9, 507 2 of 17 coatings in terms of adherence, mechanical properties, and corrosion resistance [2]. In order to optimize the results, the coatings have been deposited while changing the work distance and substrate roughness, and the effect of the pretreatment of the surface using different physical and chemical methods has been studied [3]. However, a combination of parameters relating to the combustion and gas projection pressure for producing better strength and good adhesion has not been found. Aluminum-bronze coatings have good wear and corrosion resistance properties because a copper oxide layer is formed on the surface. They are recommended for the protection and dimensional restoration of parts that are subject to harsh operating conditions [1].In the process of thermal projection by combustion, the chemical energy of combustible and combustion gases is used for the generation of the flame responsible for melting the projected particles. Oxyacetylene torches use a mixture of acetylene (C 2 H 2 ) and oxygen (O 2 ), which in a stoichiometric ratio produces a flame that reaches a temperature of up to 3386 K at 1 atmosphere of pressure [4]. An oxidant or highly oxidizing flame is when an excess of oxidizer is applied, and as a result, a primary reaction zone (cone of the flame) is obtained that is much longer than in a reductive flame or a stoichiometric flame. The particles stay longer in the hottest area of the flame, and therefore they can achieve better heating.The axial and radial temperature distribution and the changes in the velocity of the flame gases significantly affect the temperature of the particles and their behavior in flight, which influences the quality of the coating. The hot gases generated by combustion undergo complex events that involve heat and mass transfer phenomena in the boundary layers of the particle [5]. In ord...

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EIS and microstructural characterization of artificial nitrate patina layers produced at room temperature on copper and bronze

Cited by 19 publications

References 25 publications

Electrochemical impedance spectroscopy investigation of the electrochemical behaviour of copper coated with artificial patina layers and submitted to wet and dry cycles

Electrochemical impedance spectroscopy investigation of the electrochemical behaviour of copper coated with artificial patina layers and submitted to wet and dry cycles

Effects of Mg content on microstructure and electrochemical properties of Zn–Al–Mg alloys

The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

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