Electrochemical behavior of zirconia based coatings on mild steel prepared by sol–gel method

Sol–gel zirconia, yttria stabilized zirconia (YSZ) and alumina stabilized zirconia (AlSZ) coatings were deposited on mild steel to improve its corrosion resistance properties. A suitable conversion coating, prior to the sol–gel zirconia based coating was applied to minimize the interference of non-protective rust. X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and scanning electron microscopy (SEM) were used to characterize the coatings. The electrochemical corrosion behavior of the coatings was evaluated in 3.5 wt.% NaCl by potentiodynamic polarization and electrochemical impedance techniques. The sol–gel coatings exhibited barrier type protection of the substrate.

► Sol–gel zirconia based coatings deposited on MS with a prior conversion coating.
► Conversion coating comprised of composite oxides of iron and aluminum.
► It provided temporary protection to MS and suitable template for sol–gel coating.
► Sol–gel zirconia based coatings provided barrier type protection to MS.
► Sol–gel coatings reduced icorr of MS in 3.5 wt.% NaCl by 4 orders of magnitude.