The effects of immersion time on morphology and electrochemical properties of the Cr(III)-based conversion coatings on zinc coated steel surface

Corrosion performance of a hot-dip galvanized steel treated by different kinds of conversion coatings

“…Uniform coatings including some cracks were observed on both samples treated by Cr(III) and Cr(VI) conversion coatings at their optimum bath conditions. As it has been previously reported [13][14][15][16][17][18], Cr(VI) or Cr(III) has a gel like state in an un-dried state. During coating drying process, creation of an internal stress in coatings would cause shrinkage leaving some micro-cracks on their surfaces.…”

“…In addition, consumption of hydrogen ions on the zinc surface increases the local pH on the metal surface (see Eq. (2)) [13]. The increased pH can prepare a suitable condition of Co(OH) 2 or Ni(OH) 2 precipitation.…”

“…The increased pH at the surface of zinc [13], as a result of a reduction process of H + , could not be easily measured. However, as it was previously mentioned, the increased pH should be greater than 7.…”

Anti-Corrosion Performance of Cr+6-Free Passivating Layers Applied on Electrogalvanized

“…industries, is being extensively explored all over the world. In this sense, the most common transitional alternative to Cr 6+ is Cr 3+ , which is used since the mid 1970's [3][4][5][6][7][8][9]. According to Fonte et al [10], the Cr 3+ conversion layer formed in a bath containing transition metal ions such us Co 2+ , Ni 2+ and Fe 2+ showed higher corrosion resistance than those formed in a bath without transition metal ions.…”

Potency of ZnFe2O4 Nanoparticles as Corrosion Inhibitor for Stainless Steel; the Pigment Extract Study

“…Undoubtedly, they belong to the group of inhibitors, which exhibit excellent corrosion inhibitive performance. Unfortunately, chromium (VІ) is carcinogenic and toxic; hence, the use of the chromium products is restricted and prohibited strictly [1][2][3][4][5][6][7] .…”