Chromates as corrosion inhibitors

Chromates contributing to the passivating radical class are generally used as aqueous corrosion inhibitors in industries. They are generally classified as passivators. Chromates are both anodic and cathodic inhibitors, which ensures that they can boost the rate of metal dissolution in some conditions and simultaneously decrease the rate of reduction reaction (both oxygen reduction and water reduction). They are widely employed in several industries such as aqueous corrosion inhibitors in cooling water, heat exchangers, automobile radiators, diesel and gas engines, power rectifiers, power transformers, boilers at rest, etc. Because of their flexibility and beneficial cost-effectiveness ratio, chromates are mainly considered. Unfortunately, the adverse effect on the environment and human health of chromium compounds has triggered the need to rethink much of the existing industrial corrosion safety measures. This chapter covers a concise survey of the applications and limitations of the applicability of the chromates for the water/metal systems.