Applications
Approximately 136,000,000 kilograms (300,000,000 lb) of hexavalent chromium, mainly sodium dichromate, were produced in 1985. Chromates and dichromates are used in chrome plating to protect metals from corrosion and to improve paint adhesion. Chromate and dichromate salts of heavy metals, lanthanides and alkaline earth metals are only very slightly soluble in water and are thus used as pigments. The lead containing pigment Chrome Yellow was used for a very long time before environmental regulations discouraged its use. When used as oxidizing agents or titrants in a redox chemical reaction, chromates and dichromates convert into trivalent chromium, Cr3+, salts of which typically have a distinctively different blue-green color.
Read more about this topic: Chromate And Dichromate