The protective action of epoxy resins and curing agents—inhibitive effects on the aqueous acid corrosion of iron and steel

Two epoxy resins (Ciba-Geigy MY720 and Shell Epon 828) and three curing agents; 4,4′-diaminodiphenyl-sulphone (DDS), 4,4′-diaminodiphenyl methane (DDM) and diethylenetriamine (DETA) have been examined for their inhibitive effects towards pure iron and mild steel in 0.5 M de-aerated H 2SO 4. Both epoxies are inhibitive over the range of concentrations studied for both metals but the curing agents can stimulate corrosion particularly at low concentrations. An attempt has been made to correlate adsorption and compound action with molecular structure. The use of more than the stoichiometric amount of epoxy resin in a paint formulation may be desirable to utilize the inhibitive action of these compounds.