La^(3+)对Zn-Fe合金镀层在硫酸溶液中腐蚀行为的影响

Effect of La^(3+) on corrosion behavior of Zn-Fe alloy coating in sulfuric acid solution

电镀液中加入镧盐,在A3钢表面电镀Zn-Fe合金薄膜,选择酸性腐蚀介质,研究La3+对Zn-Fe合金镀层腐蚀行为的影响.用线性扫描伏安法和交流阻抗法,研究Zn-Fe合金镀层在30℃的0.20mol·L-1H2SO4溶液中的腐蚀行为.用XRD和SEM研究Zn-Fe合金镀层在腐蚀前后的微观结构和形貌的变化.结果表明:加入镧盐,不改变Zn-Fe合金镀层的晶面择优取向,但影响各晶面衍射峰强度,使镀层结晶粒度变小;当加入La2(SO4)3为0.90g·L-1时,Zn-Fe合金镀层变得致密均匀,电结晶生长形态呈现层状;镀层的致钝电流密度(Jpp)和维钝电流密度(Jp)显著降低,极化电阻Rp增大,镀层具有良好的耐蚀性能.

The effects of Lanthanum ions on the corrosion behavior of Zn-Fe alloy coating in acid corrosion solution,which was electroplated on the surface of A3steel substrate with various electrolytes of Lanthanum salt,were investigated.The corrosion behavior of the Zn-Fe alloy coating was studied by the Linear sweep voltammetry and AC impedance in the 0.20mol·L-1 sulfuric acid solution at 30℃.The microstructure and shape of Zn-Fe alloy coating before and after corrosion was studied by XRD and SEM.The results indicate that the addition of lanthanum salt decreases the grain size of Zn-Fe alloy coating and retains the preferred orientation of Zn-Fe alloy coatings,but affects the intensity of diffraction for crystal planes.When 0.90g·L-1 La2（SO4）3is added in the electrolytes,the coatings of Zn-Fe alloy are more uniform and compact,and the electrocrystallization appears layered.The Jppand Jpof Zn-Fe alloy coating are reduced evidently,Rpis increased,and the Zn-Fe alloy coating has better corrosion resistance.