Modification of zinc powder to improve the corrosion resistance of weldable primers

This paper reports the modification of zinc powder to improve the corrosion resistance of weldable primers. These primers are thin zinc rich organic coatings applied by roll coating at the steel manufacturer. The automotive industry uses them to protect areas in the car body that become inaccessible after joining processes. In this work, with the objective of increasing the corrosion resistance of these systems, the zinc particles were chemically treated or simply replaced by powder of 55AlZn alloy. The rest of the formulation remained intact. The performance of the commercial and modified formulations was compared by SEM, SVET and EIS. The best results were obtained when the zinc powder was replaced by powder of the aluminium zinc alloy.