Mn Oxide Film as Corrosion Inhibitor of Zn-Mn Coatings

摘要

Despite the technological relevance of galvanizedsteels, in past years not enough attempts have been made toimprove the corrosion resistance of hot dip galvanizing Zncoatings by alloying. In the present work a Zn-0.5 percent Mncoating was produced under controlled laboratory conditions. Thelevel of corrosion protection offered by the addition of Mn to theZn coating was investigated. Polarization measurements in sodiumchloride solution and x-ray diffraction were used to determinetheir corrosion behavior. The corrosion rates of Zn and Zn-0.5percent Mn coatings were in the same order of magnitude.However by comparing the corrosion rate on several samples, areduction of the corrosion rate of the samples containing Mn wasobserved. This result was attributed to the presence of an oxidemanganese film on the surface coating. This film was studied byAES and XPS spectroscopies. Preliminary results are presented in this paper.