LOCATION OF CORROSION ON IRON AND CARBON-STEEL SURFACES WITH CREVICES

Corrosion of iron and carbon steel surfaces within crevices formed by a thin piece of glass, was assessed using a Video microscope, current density mapping, and corrosion potential measurements. Corrosion initi ated adjacent to the glass and spread slowly to other parts of the fre ely exposed areas. For many days, no corrosion was found under the gla ss in simulated tap water, NaCl, and Na2SO4 solutions. An explanation for the protection oi the crevice has been suggested whereby alkalizat ion with partial reduction of the passive oxide protects the surface u nder the glass from corrosion.