硫酸盐浴中电沉积Zn-Co合金涂层用于Q235钢的腐蚀防护OA

Q235 steel is susceptible to serious corrosion failure when it is subjected to highly corrosive environments such as high salt,humidity and industrial atmospheres in long-term service.To address this phenomenon,Zn and Zn-Co alloy coatings were prepared by electrodeposition on the surface of Q235 steel in sulfate baths,and the corrosion resistance of the coatings was studied in detail.The electrochemical test results show that Zn coating prepared at a current density of 2 A/dm2 has a more positive corrosion potential and a lower corrosion current density,demonstrating good corrosion resistance.Under the same current density,when the molar ratio of Zn2+to Co2+in the plating solution is controlled at 9∶1,the prepared Zn-Co alloy coating exhibits a lower corrosion current density(1.122 μA/cm2)compared to Zn coating,along with a higher coating resistance(2389 Ω·cm2)and charge transfer resistance(1 705 Ω·cm2).Furthermore,the charge transfer resistance of Zn-Co alloy coating is 2.097 times that of Q235 steel.Chemical composition analysis reveals that the Zn-Co alloy coating contains mass fraction 0.7%of cobalt.The trace amount of cobalt significantly enhances the corrosion resistance of Zn-Co alloy coating,providing good protection for Q235 steel.