MOLYBDATE BASED PASSIVATION OF ZINC

In order to reduce corrosion rates, zinc plated parts are usually chro mated. Recently chromates have caused increasingly environmental conce rn, for both allergic effects among workers touching chromated parts a nd toxic effects on fish, plants and bacteria. A molybdate based alter native has been developed to replace chromates in several passivation applications. Depending on the environment in which the passivated par ts are to be exposed, the protection that this alternative treatment p rovides range from less efficient to more efficient as compared to chr omate. These aspects as well as issues such as; cost, stability, layer composition and test results from several different corrosion tests a re discussed.