Inhibition of Localized Corrosion of Hot Dip Galvanized Steel by Phenylphosphonic Acid

Phenylphosphonic acid (H 2 PP) is investigated as a corrosion inhibitor of hot dip galvanized steel (HDG) fully immersed in a 5% (w/v) sodium chloride electrolyte. An in-situ Scanning Vibrating Electrode Technique (SVET) is used where concentrations of H 2 PP are systematically added to the electrolyte in neutral conditions. H 2 PP, at a concentration of 5 × 10 −2 mol dm −3 , is shown to effectively inhibit localized corrosion over a 24 h period with 96% efficiency. H 2 PP is compared with a sodium phosphate (Na 3 PO 4 ) inhibitor at the same concentration over a wide pH range.