Depth Elemental Imaging during Corrosion of Hot-Dip Galvanized Steel Sheet by Confocal Micro XRF Analysis

The elucidation of the mechanism for steel corrosion under a coating layer has been attracting research attention. Herein, we utilized a confocal micro-X-ray fluorescence (XRF) analytical instrument to conduct non-destructive elemental analysis near the surface of a steel sheet. Using this method, elemental map images of steel sheet cross sections were obtained without sample destruction. To confirm corrosion suppression in the presence of Mg ions, we observed the corrosion behavior of hot-dip galvanized steel sheets immersed in an aqueous NaCl solution to which Mg ions were added. By using the confocal micro XRF system, the elution of the coating components and the precipitation process of the corrosion products were confirmed.