Corrosion of Cathodes in Anodic Protection Systems in Hot Concentrated Sulfuric Acid—Part 1: Conventional Cathodes

The present investigation was undertaken to explore the corrosion that occurs under cathodic polarization for alloys commonly used as cathodes in anodically protected heat exchangers containing hot concentrated sulfuric acid (H2SO4) solutions. Weight loss measurements after galvanostatic cathodic polarization showed that accelerated corrosion of the cathodes commonly used in anodically protected H2SO4 coolers (UNS N06200 and N10665 alloys) occurs over a limited range of current densities far removed from the open-circuit potential. This article discusses these cathode materials. Part 2 (to be published in August 2005 MP) will discuss potential new cathode materials.