THE EFFECT OF ANTIMONY ADDITIONS ON HOT-DIP GALVANIZED COATINGS

Hot dip galvanized coatings with minor amounts of antimony or lead were evaluated with respect to their surface appearance, corrosion behavior and spangle orientation. The coating surfaces with many crater-like pits and a higher surface density of spangle boundaries were more susceptible to corrosion attack. The surface of bright spangles was parallel to the (00.1) plane and was crystallographically more homogeneous than that of dull spangles whose surface was mostly parallel to the (10.1) plane. This seems responsible for higher corrosion resistance of bright spangles than any other spangles. Antimony existed within the coating rather than on the coating surface. Electron diffraction pattern from antimony-containing phase showed Sb2Zn3 structure.