Study of the inhibition ability of benzotriazole on the Zn-Mg coated steel corrosion in chloride electrolyte

The corrosion inhibition of Zn-Mg coated steel by benzotriazole was investigated in sodium chloride solution. Electrochemical and analytical measurements combined with surface analyses indicate that benzotriazole inhibits the corrosion reactions by forming a complex between Zn2+ and the anionic form of benzotriazole BTA present near the surface where pH increases due to Mg dissolution. The complex reinforces the corrosion product layer composed of zincite ZnO which precipitates on the surface. If a benzotriazole/chloride ions ratio of 1/100 is respected and if the presence of the inhibitor is always maintained in the chloride medium, a sustainable barrier layer is assured.