Abstract
Epoxy coatings were formed by cathodic electrodeposition of an epoxy resin on aluminium and modified aluminium surfaces (phosphatized, chromatized-phosphatized and anodized aluminium) using a constant voltage method (resin concentration 10 wt.%, temperature 27 oC, applied voltage 250 V). The corrosion behavior of these coatings was investigated during exposure to 3% NaCl using electrochemical impedance spectroscopy (EIS) and polarization measurements. From the dependence of resistance, capacitance and relative permittivity of the coating, obtained from EIS, on the rate of hydrogen evolution reaction in the electrodeposition bath, obtained from polarization curves, it can be observed that the epoxy coating on aluminium and modified aluminium surfaces is a good barrier against the transport of corrosive agents. The time corresponding to contact between electrolyte and aluminium surface under the coating is greater in the case of surface modification by chromato-phosphatized and anodized aluminium than in the case of phosphatize one.
Highlights
The ability of an organic coating to protect a metal substrate against corrosion generally depends on:[1,2,3,4] (a) the quality of the coating, i.e., its chemical and mechanical properties, adhesion to the substrate, water uptake and permeability to water, oxygen and ions; (b) the characteristics of the substrate and the surface modification; (c) the properties of the metal/coating interface
From the dependence of resistance, capacitance and relative permittivity of the coating, obtained from electrochemical impedance spectroscopy (EIS), on the rate of hydrogen evolution reaction in the electrodeposition bath, obtained from polarization curves, it can be observed that the epoxy coating on aluminium and modified aluminium surfaces is a good barrier against the transport of corrosive agents
The aim of this work was to investigate the electrochemical properties of epoxy coatings on aluminium and modified aluminium surfaces and to explain the effect of surface modification on the protective properties of epoxy coatings electrodeposited on aluminium and modified aluminium
Summary
The ability of an organic coating to protect a metal substrate against corrosion generally depends on:[1,2,3,4] (a) the quality of the coating, i.e., its chemical and mechanical properties, adhesion to the substrate, water uptake and permeability to water, oxygen and ions; (b) the characteristics of the substrate and the surface modification; (c) the properties of the metal/coating interface. The Study of Corrosion Stability of Organic Epoxy Protective Coatings followed by electrocoagulation of resin micelles at the cathode surface by neutralization of positively charged groups in the resin with electrochemically generated OH – ions:. The aim of this work was to investigate the electrochemical properties of epoxy coatings on aluminium and modified aluminium surfaces (anodized aluminium, phosphatized and chromatized–phosphatized aluminium) and to explain the effect of surface modification on the protective properties of epoxy coatings electrodeposited on aluminium and modified aluminium. The previously pretreated aluminium were electrochemically anodized in 20% H SO 24.
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