Investigation of Zinc Dimercaptothiadiazole as a Corrosion Inhibitor for Steel

The mechanism of corrosion inhibition of zinc dithiomercaptothiadiazole (Zn(DMcT)2) has been known and elucidated. The efficacy of (Zn(DMcT)2) as used in primer coatings for corrosion inhibition on steel alloys such as 1010 steel and 4130 high strength steel under neutral pH conditions was investigated by accelerated corrosion testing methodologies. Solution-state studies and surface elemental analyses were conducted to determine the possible mechanism of corrosion inhibition. Solution state experiments showed a correlation between increasing Zn(DMcT)2 amounts and increased polarization resistance, but DMcT on its own did not show this relationship. Under neutral pH conditions, it was determined that Zn(II) species such as Zn(OH)2, Zn(DMcT)2, and possibly ZnO were deposited on the steel surface, providing corrosion protection.