Electrochemical behaviour of SiO2 sol-gel coatings on stainless steel

Abstract

SiO2 coatings onto stainless steel substrates have been prepared by sol-gel in order to study the performance and mechanism of attack in different corrosive solutions. The electrochemical behaviour of the samples has been evaluated by Electrochemical Impedance Spectroscopy using NaCl and HCl as electrolytes. Comparative tests have been performed on samples with one and two silica layers as well as on uncoated ones. SiO2 coatings produce no important protection of stainless steels subjected to electrochemical corrosion. This behaviour may be explained by micropores and microcracks produced during the coating sintering. © 1995 Kluwer Academic Publishers.