Effects of rare earth metal addition on surface morphology and corrosion resistance of hot-dipped zinc coatings

摘要

Effects of rare earth metals (REM) addition on surface morphology and corrosion resistance of hot-dip galvanised steel were investigated. The corrosion resistance of steel samples galvanised with zinc and zinc alloys containing 0.05, 0.1, 0.2 and 0.5 wt.% REM were evaluated by various corrosion tests such as weight loss in salt spray chamber and natural sea water, sacrificial protection ability in contact with fog in salt spray chamber and after immersion in sea water, potential-time in sea water and linear polarisation in sodium chloride solution. Surface morphology and nature of the corrosion products were also investigated. The results indicated that the addition of small amounts of REM to the molten zinc galvanising bath can improve the corrosion resistance of hot-dip galvanised steel. Mechanisms by which the corrosion resistance of hot-dip galvanised steel are improved in presence of REM have been discussed.