Application of EMF-pH Diagrams to Corrosion Prediction^* Available to Purchase

EMF-pH diagrams calculated from physical property data can be practical tools to air in corrosion prediction. The EMF-pH diagrams of two practical systems relating to actual process corrosion problems are examined. These are titanium in a concentrated HCl-NaCl solution containing an organic component modeled as aspartic acid, and a cadmium electrode in the presence of dissolved EDTA. Procedures for estimating the needed thermodynamic properties are discussed in detail. Both examples show that placement on these diagrams of the pH and the measured corrosion potential provide a useful way to relate the theoretical thermodynamic diagram to the real world. By coupling the EMF-pH diagram with these properly determined properties, useful insights are gained so reasonable hypotheses can be established and appropriate further experiments can be run.