Effects of sol-gel coatings on the localized corrosion behavior of 304 stainless steel

The corrosion behavior of ceria/titania coated 304 stainless steel (304 SS) was studied by anodic polarization measurements in 0.05 N NaCl. Coatings were prepared by sol-gel methods, were approximately 0.5 mu m thick and bonded well to the substrate. The as-received stainless steel suffers sensitization at the coating cure temperature of 900 degrees C and a 500 mV decrease in pitting potential results. When the coating is present, however, despite sensitization of the substrate, the pitting potential is about the same as for the as-received stainless st el. The latter result indicates that the coating does protect the underlying metal from pitting corrosion. Following polarization, coated samples show significantly fewer pits than as-received stainless steel and resist crevice attack.