Corrosion inhibition of mild steel by polyhydric alcohol phosphate ester (PAPE) in natural sea water

Abstract

The corrosion inhibition of mild steel by polyhydric alcohol phosphate ester (PAPE) in natural sea water has been investigated by polarisation curves, electrochemical impedance spectroscopy (EIS) and surface analytical techniques. The results have shown that PAPE acts as a mixed type (anodic and cathodic) negative catalytic effect interface inhibitor and that the adsorption is of the Langmuir type. The inhibitor can adsorb immediately and compactly on the steel surface, the thickness of the film increasing with time. The adsorption behaviour involves the formation of complexes between the R1 functional group of the PAPE molecular structure and metal ions on the steel surface, such as Fe²⁺, Mg²⁺, Ca²⁺, etc.