Acidic surface treatment of mild steel with enhanced corrosion protection for silane coatings application: The effect of zinc cations

Abstract Surface pretreatment is a key influential parameter on the protective function of silane coatings. The present study considers examining the effect of zinc cations addition to acid pretreatment solution on subsequent silane coating corrosion protection on mild steel. The electrochemical properties of subsequent silane coating on pretreated plates were assessed by electrochemical impedance spectroscopy and polarization measurements. The polarization resistance increased approximately two times in the presence of 3 g·L−1 zinc cations, which agreed with electrochemical impedance spectroscopy data. Energy-dispersive X-ray spectroscopy (EDS) detected 3.13 wt% Zn on the zinc cation-pretreated substrate. Field emission scanning electron microscopy revealed surface morphological changes of pretreated samples in the presence of zinc cations. Contact angle, atomic force microscopy, grazing incidence X-ray diffraction, and EDS tests on the surface of pretreated samples evidenced that zinc cations reduced the oxidation and corrosion attacks on the steel surface. Raman spectroscopy revealed formation of a complex between Zn2+ cations and the organic inhibitor.