The Influence of Graded Amount of Potassium Permanganate on Corrosion of Hot-Dip Galvanized Steel in Simulated Concrete Pore Solutions

This paper evaluates the amount of KMnO4 in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO4− (10−4, 10−3, 10−2 mol·L−1), corrosion behaviour is examined with regard to hydrogen evolution and composition (protective barrier properties) of forming corrosion products. The corrosion behaviour of HDG samples is evaluated using Rp/Ecorr and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO4− ion concentration to prevent the corrosion of coating with hydrogen evolution is 10−3 mol·L−1; lower concentrations only prolong the time to passivation (corrosion with hydrogen evolution). The highest used MnO4− concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in MnII/MnIII phases.