CORROSION MECHANISMS AND COSMETIC CORROSION ASPECTS OF ZINC-ALUMINIUM-MAGNESIUM AND ZINC-CHROMIUM ALLOY COATED STEEL STRIP(170)

摘要

Corrosion mechanisms and cosmetic corrosion behaviour of Zn-Al-Mg alloy coating (ZM/HDG) andZn-Cr alloy coating (ZCE/EG) in comparison to conventional zinc coating (Z/HDG) are presented.The outstanding corrosion protection performance of the new zinc-alloy type coatings is based onthe formation of special corrosion inhibiting layers. In the case of ZM/HDG the nature of thecorrosion product layer is based on Hydrotalcite. Up to six fold corrosion protection was observedeven with half of the coating thickness of ZCE/EG coatings and paint creepage is reduced down to50% in comparison to conventional zinc coatings (Z/HDG, ZE/EG). This clear improvement incorrosion protection is surely one of the most important product properties.