Characterization of Hybrid Sol-Gel Coatings Doped with Hydrotalcite-likeCompounds on Steel and Stainless Steel Alloys

Abstract

Hybrid sol-gel organic-inorganic coatings have been extensively studied to their active properties to protect different metal surfaces. Incorporation of non-hydrolysable groups in conjunction with different molar ratio of sol-gel precursors dissolved in distinct solvents lead to an increment of better protective barrier properties. Different hybrid silica sol-gel coatings were prepared changing the type and content of solvent (2-propanol, ethylacetate, ethanol). Coatings were deposited by dip-coating method on AISI 304 stainless steel and low carbon steel. Incorporation of ethyl acetate in the sol-gel formulation provided the best results on low carbon steel whereas 2-propanol resulted adequate for stainless steel by means of electrochemical impedance (EIS) characterization. In addition, EIS showed a marked improvement of the corrosion resistance when hydrotalcite particles were incorporated into the coating. Scanning electron microscopy (SEM) revealed homogeneous coating deposition for low carbon steel samples. However, stainless steel samples developed cracks along the sol-gel coating.