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.