Evaluation of Corrosion Inhibitors for Component Cooling Water Systems

Electrochemical techniques were used to study the inhibition effects of molybdate (MoO₄²⁻), MoO₄²⁻ + nitrite (NO₂⁻ ), MoO₄²⁻ + tolyltriazole (TTA, CH₃C₆H₄N₃H), and MoO₄²⁻ + NO₂⁻ + TTA on the general and pitting/crevice corrosion of carbon (C) steel and some copper (Cu) alloys common to component cooling water systems (CCWS) exposed to deionized water open to ambient air or purged with nitrogen (N₂). Some tests were performed in deionized water faulted with chloride (Cl⁻) at concentrations of 150 ppb or 1.5 ppm and with 1.5 ppm Cl⁻ plus 1.5 ppm sulfate (SO₄²⁻). Results were compared with the inhibition effects of 200 ppm chromate (CrO₄²⁻).