Abstract
Previous studies have shown that the barrier effect and the performance of organic-inorganic hybrid (OIH) sol-gel coatings are highly dependent on the coating deposition method as well as on the processing conditions. However, studies on how the coating deposition method influences the barrier properties in alkaline environments are scarce. The aim of this experimental research was to study the influence of experimental parameters using the dip-coating method on the barrier performance of an OIH sol-gel coating in contact with simulated concrete pore solutions (SCPS). The influence of residence time (Rt), a curing step between each dip step and the number of layers of sol-gel OIH films deposited on hot-dip galvanized steel to prevent corrosion in highly alkaline environments was studied. The barrier performance of these OIH sol-gel coatings, named U(400), was assessed in the first instants of contact with SCPS, using electrochemical impedance spectroscopy and potentiodynamic methods. The durability and stability of the OIH coatings in SCPS was monitored during eight days by macrocell current density. The morphological characterization of the surface was performed by Scanning Electronic Microscopy before and after exposure to SCPS. Glow Discharge Optical Emission Spectroscopy was used to investigate the thickness of the U(400) sol-gel coatings as a function of the number of layers deposited with and without Rt in the coatings thickness.
Highlights
The durability of reinforced concrete structures (RCS) is a topic of general concern due to the high costs of rehabilitation [1]
It is of extreme importance to prevent/mitigate the corrosion of RCS exposed to aggressive environments
Organic-inorganic hybrid (OIH) sol-gel coatings are a new generation of multifunctional materials where the intermolecular interactions between the macromolecular existing structures and metallic surface are of relevancy for the material properties, such as low porosity, low rigidity and adhesion to the substrate [20]
Summary
The durability of reinforced concrete structures (RCS) is a topic of general concern due to the high costs of rehabilitation [1]. Organic-inorganic hybrid (OIH) sol-gel coatings are a new generation of multifunctional materials where the intermolecular interactions between the macromolecular existing structures and metallic surface are of relevancy for the material properties, such as low porosity, low rigidity and adhesion to the substrate [20]. These materials can be produced under mild conditions on an industrial scale using well established methods such as spray, dip and spin coating.
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