Technical Paper
Hexa chrome free passivation — Experience as part of ELV Implementation
2008-01-09
2008-28-0076
Hexavalent chromium Cr(VI) is recognized as a known human carcinogen via inhalation. This is banned to be used in Corrosion Protective Coatings as per End Life of Vehicle regulation (ELV) 2000/53/EC effective July'07 in EU. Traditionally all automotive metallic components which are Zinc plated are passivated with a thin Chromate layer to add to its brightness and protect it from premature corrosion. These Chromate coatings (or passivation) are generally Hexavalent chromium based and available in four grades: clear, yellow, olive drab, and black. Alternatives in the form of Trivalent Chromium Cr(III) are now available. By nature, both these passivations have different properties. Trivalent chromium has high temperature resistance but low wear resistance thus does not possess self healing properties. Also, its cost is significantly higher compared to hex chrome solutions.