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 environmentfriendly. | Vietnam Journal of Science and Technology 55 (5B) (2017) 57-65 PROTECTION OF STEEL JISG 3141 WITH CHROMIUM-FREE CONVERSION COATING BASED ON INORGANIC SALT (Zr/Ti/Mo) Duong Thi Hong Phan1, *, Le Minh Duc1, Dao Hung Cuong2 1 The University of Da Nang, University of Science and Technology, 54 Nguyen Luong Bang, Da Nang, Viet Nam 2 The University of Danang, University of Education, 459 Ton Duc Thang, Da Nang, Viet Nam * Email: dthphan@ Received: 1 August; Accepted for publication: 5 October 2017 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 environmentfriendly. Keywords: chromium-free, Molybdate, the salt spray, conversion coating, steel. 1. INTRODUCTION SPCC-JISG 3141, which represents a commercial quality cold rolled steel, offers high corrosion resistance compared to other steels. However, they display poor resistance to localized pitting corrosion in aqueous solutions containing complex agents such as .
