Corrosion Characteristics of Zn-Ni-Ag Composite Coating under Sulfate Reducing Bacteria Condition

A Zn-Ni-Ag composite coating was prepared on the surface of 20 steel by electrodeposition method, and the corrosion behavior of the Zn-Ni-Ag coating and 20 steel under sulfate reducing bacteria (SRB) conditions was studied through static coupon test and electrochemical test. Results showed that the Zn-Ni-Ag coating had a certain inhibitory effect on the growth of SRB. After 10 days of coupon test, the number of SRB in 20 steel system was stable at 13×10⁷/mL, while the number of SRB in Zn-Ni-Ag coating system was stable at 5.0×10⁷/mL. In the SRB environment, the Zn-Ni-Ag coating had good corrosion resistance, and the corrosion rate was always kept at a low level, and was always lower than that of 20 steel. The corrosion resistance of the Zn-Ni-Ag coating was stable in the SRB environment. Therefore, the Zn-Ni-Ag coating could provide protection for carbon steel in the presence of SRB.