Self healing ability of silicate conversion coatings on hot dip galvanized steels

► Single silicate coating on hop dip galvanized steel possesses self sealing ability. ► Self healing ability of the silicate coating depends on SiO2:Na2O molar ratio. ► Silicate anions migrate from the coating to the scratch during the corrosion process. ► A new conversion coating composed of Zn, O and Si is formed in the scratched area.