Effects of Particulate Silica Coatings on Localized Corrosion Behavior of AISI 304SS under Atmospheric Corrosion Conditions

Abstract

The effects of a coating of silica particles on the localized corrosion behavior of AISI 304 stainless steel (304SS) during drying of thin electrolyte layers in controlled relative humidity environments were investigated by measurements of the transients of open-circuit potential (OCP) and galvanic current. The silica coatings were composed of spherical silica particles and were deposited on 304SS by cathodic electrophoretic deposition. It was confirmed that the silica layer worked very well as a host layer to soak up electrolyte solutions and that it remained intact under wet and dry conditions. OCP and galvanic current transients indicated that the silica layer affected propagation more than initiation of pitting corrosion. The propagation of pitting corrosion for silica-coated samples was slower than for uncoated 304SS.