Effect of additives on the properties of phosphate conversion coating on electrogalvanized steel sheet
Journal
Corrosion Science
Journal Volume
83
Pages
137-146
Date Issued
2014
Author(s)
Su, H.-Y.
Abstract
Ni2+ and Mn2+ ions have been added separately to the phosphate solution to minimize the porosity of the phosphate conversion coating on electrogalvanized steels. Results showed that the Ni2+ or Mn2+ in the solution reduced the grain size and porosity of the phosphate coating; thereby, the corrosion resistance was enhanced. However, Ni2+ and Mn2+ played a different role in the coating formation. Ni2+ in the solution was reduced by Zn to form Ni, which enhanced the dissolution of Zn to promote the nucleation of hopeite grains. Mn2+ in the solution facilitated the nucleation by increasing the impingement of reacting species. © 2014 Elsevier Ltd.
Type
journal article