Hot dip Zn-5Al coatings with improved corrosion resistance of reinforcement steel

The article presents the results of tests of Zn-5Al coatings obtained on reinforcement bars made of B500SP steel. The microstructure using Scanning electron microscopy (SEM) and chemical composition in micro-regions using Energy dispersive spectroscopy (EDS) are shown. The electrochemical parameters of the corrosion process of the coatings were determined and the mechanical properties of the reinforcement bars after the coating were tested. It was found that the coating consists of the outer layer consisting of hypoeutectic regions of Al solution in Zn (α) and the ZnAl eutectic (α+β), and a diffusion layer composed of FeAl₃ phase. Potentiodynamic tests have shown that the Zn-Al5 coating provides sacrificial protection for the reinforcement steel and has a much lower corrosion current density compared to the traditional zinc coating.