Corrosion resistance and adhesion behavior of an octa-(aminopropyl) polyhedral oligomeric silsesquioxane-modified graphene oxide-incorporated conversion coating for hot-dip galvanized steel

Graphene oxide (GO) was modified by a novel octa-(aminopropyl) polyhedral oligomeric silsesquioxane (OA-POSS) to improve its dispersion in a waterborne matrix. The modified GO was incorporated into preparing an eco-friendly conversion coating for the hot-dip galvanized layer. The compositions of the conversion coatings were unaffected by the presence of the mGO, but surface defects were modified. The corrosion current density was decreased to 6.50 × 10 −5 A/cm 2 and the corrosion rate was reduced to 9.69 mm/year by modified GO incorporation. Increased resistances to charge transfer and mass diffusion at one order of magnitude were also obtained. Moreover, the adhesion strength of the as-prepared conversion coating was improved 70% after the mGO addition, which effectively inhibited topcoat exfoliation.