Multicomponent Corrosion Inhibitor System for Recirculating Cooling Water Systems

Abstract

This paper presents the results of a study that was undertaken to optimize the ratio of the components of a new multicomponent inhibitor blend composed of nitrite/molybdate/inorganic phosphate. The mechanistic aspects of inhibition of the blend were also studied. Weight-loss and polarization data indicated that the optimum ratio of nitrite:moiybdate:phosphate:orthophosphate was 3:2:1:1. The mechanism of inhibition in aerated tap water in the pH range 6.5 to 8.5 seemed to be a direct result of action on the anodic dissolution process. It appeared that the molybdate component promoted passive film formation. The blend had some obvious advantages compared with molybdate or nitrite blends. A decrease in the molybdate concentration would lower costs, whereas a decrease in nitrite concentration would reduce microbiological fouling tendency.