Pulse potential method-assisted construction and regulation of a trivalent chromium conversion coating on hot-dip coated steel sheet

摘要

A pulse potential method (PPM) was used to regulate the formation of Cr(III) conversion coating (TCC) on hot dip Zn-55 % Al-1.6 % Si. The micromorphology analysis and the contact angel measurement showed that the application of PPM changed the micro-features and hydrophobicity on the surface of TCC. Surface XPS analysis indicated that PPM increased the proportion of hydroxides and greatly reduced the content of Cr(VI) on TCC. Better corrosion resistance of the TCC was measured using multiple electrochemical methods when the pulse square-wave potential E-p = -0.10 V. The results corroborated the positive role of PPM in improving the temporary corrosion resistance of hot-dip coating.