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 KMnO(4) in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO(4)(−) (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 R(p)/E(corr) and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO(4)(−) 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 MnO(4)(−) concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in Mn(II)/Mn(III) phases.