Molten Zinc Corrosion of WC-Co Coatings in Al-Added Zinc Bath

To increase the service life of a sink roll in a continuous galvanizing line has been an important issue in steel industry. It was shown that sink rolls are vulnerable to molten zinc corrosion and can be improved by thermal spraying with WC-Co coatings. Four WC-12Co thermal sprayed coatings were investigated in this study. Samples were immersed in Al-added zinc bath (460°C) for testing. The results show that the conventional coatings are more resistant to molten zinc corrosion than the nanostructured ones. It was also found that coatings containing η- phase have longer life in the zinc bath. Accumulation of Al on the coating surface was also observed.