Corrosion Inhibition of Copper by Selected Thiol Compounds

Electrochemical analysis of the corrosion inhibiting performance of two di-sulfide bases, the salts of 2,5 dimercapto-1,3,4 thiadiazole (DMTD) and 1-pyrrolidine dithiocarbamate (PYRR) in neutral NaCl for pure copper demonstrates that the compounds inhibit anodic and cathodic reactions and they exhibit synergy as a 1:1 mixture under open circuit conditions. The inhibitors are both anodically electro-active which may allow the irreversible formation of protective coatings. At open circuit the combination of the two inhibitors behaves synergistically and results in a corrosion exchange current density for Cu in 0.2 M NaCl of 0.03µA/cm2.