ATMOSPHERIC CORROSION PROPAGATION ON GALVANIZED STEELS UNDERNEATH PAINTS WITH SCRATCHS
涂膜破坏后膜下镀锌钢板大气腐蚀扩展研究

Corrosion propagation on galvanized steels underneath paints with a desired scratchs was studied after atmospheric exposure for one and half year by SEM and EDS,meanwhile the corrosion resistance of the painted steels which were electrogalvanized,hot-dip galvanized and electrogalvanized and then phosphated before painting was compared.The results showed that the corrosion resistance of the steels underneath paints with the desired scratchs was independent on the fabrication means of Zn coatings but not the thickness Zn coatings.Phosphate treatment showed a harmful effect on the corrosion resistance in this study.The hot-dip galvanized steel showed the same corrosion resistance as the electrogalvanized steel even though detachment occurred between the Zn coating and the paint.Chlorine enriched in front of the corrosion product while sulfur distributed the whole area.