Effect of La³⁺ on Corrosion Resistance of Zn-Fe Alloy Coating

The effect of La3+ on the corrosion behavior of Zn-Fe alloy coating in acid solution were investigated.The corrosion behavior of Zn-Fe alloy coating was studied by the linear sweep voltammetry and AC impedance in 0.20 mol/L sulfuric acid solution at 30 ℃.The microstructure of Zn-Fe alloy coating before and after corrosion was studied by XRD and SEM.The results indicated that the grain size of Zn-Fe alloy coating turned smaller,the preferred orientation of Zn-Fe alloy coatings were not changed and the intension of diffraction for crystal planes were affected after adding lanthanum salt.When 0.90 g/L La2(SO4)3 was added into the electrolytes,the coatings of Zn-Fe alloy were more uniform and close together,and the shape of electrocrystallization turned to layer.The ipp and ip of Zn-Fe alloy coating were reduced evidently,Rp was increased,and the Zn-Fe alloy coating had better corrosion resistance.