PROTECTION OF STEEL JISG 3141 WITH CHROMIUM-FREE CONVERSION COATING BASED ON INORGANIC SALT (Zr/Ti/Mo)

Duong Thi Hong Phan

Abstract


Chromium-free conversion coatings based on Zr/Ti/Mo compounds were prepared to improve the corrosion resistance of the SPCC-JISG 3141 steels. Passivation layer containing Zr, Ti and Mo has been successfully carried out on steel by dipping in solution of 17 g/l Na2MoO4, 8 g/l K2ZrF6, 1 g/l H2TiF6 and pH = 5. Scanning electron microscopy couples with energy - dispersive spectroscopy (SEM/ EDX) were used to provide the microscopy structure information and presence of Zr/Ti/Mo on surface of the steels. The corrosion potential and current of coating in case of with and without passivation layer on the steels was determined by potentiodynamic polarization test, showed that the corrosion current density decreased when using Zr/Ti/Mo coating. The passivation layer provided the corrosion resistance of coating. Furthermore, the salt spray test (Model SAM Y90) evidenced the higher corrosion resistance of the coated samples compared to bare steel when electro - deposition coating (ED) applied. The treatment using inorganic salt could significantly increase the anticorrosion of steels with their environment-friendly.


Keywords


chromium-free, Molybdate, the salt spray, conversion coating, steel.

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DOI: https://doi.org/10.15625/2525-2518/55/5B/12210

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Published by Vietnam Academy of Science and Technology