Cut-edge corrosion study on painted aluminum rich metallic coated steel by scanning vibrating electrode and micro-potentiometric techniques

Aluminium-rich metallic coated steels were found to be especially sensitive to cut-edge corrosion in various climates for both painted and unpainted material. The aim of this work is to study the corrosion process in the cut-edge and the effect of aluminium presence in the metallic coating. In this frame, painted zinc metallic coated steel samples with different amount of Al were studied by scanning vibrating electrode technique coupled with a scanning ion-selective electrode technique (SVET/SIET). SVET and micro-potentiometric pH measurements were performed quasi simultaneously. The experiments were performed in continuous immersion in 0.05 M NaCl. As a result, differences in pH and activity for the studied systems could be linked to the presence of aluminium. Formed corrosion products were identified by Raman spectroscopy, FTIR spectroscopy, SEM-EDX and by analyzing the local pH in the area of precipitation.