Surface characteristics and corrosion resistance of spangle on hot-dip galvanized coating

This work investigated spangle on Zn-0.05Al-0.2Sb galvanized coating with shiny, feathery and dull morphology. The main goal was to determine the influence of surface characteristics on the anti-corrosion performance of the produced spangle. Experimental results showed that spangle displays an increasing electrochemically active trend from shiny, feathery to dull spangle, which is attributed to the combined factors of surface micro-roughness, surface texture, and surface segregation of spangle. In addition, the Sb3Zn4 particles precipitated on the coating surface play an important role in the corrosion resistance of spangle. Difference in morphology of spangle leads to difference of surface micro-roughness, surface texture, surface segregation, and finally leads to difference of corrosion resistance of spangle, which is discussed by a proposed spangle growth model.