Cu-50Cr合金在含Cl^-介质中的腐蚀电化学行为研究

利用动电位扫描法，结合电化学交流阻抗技术研究了用传统电弧熔炼制备的Cu^-50Cr合金在不同Cl^-浓度介质中的腐蚀电化学行为．结果表明：随Cl^-浓度的增加，自腐蚀电位均出现不同程度的负移，腐蚀电流增大，腐蚀速度加快；Cu-50Cr合金在中性Na2S04溶液中未出现钝化现象，加入Cl^-后，出现了钝化现象，但钝化区间很窄．从交流阻抗谱及拟合结果分析得知：在0．05mol／LNa28O4和0．05mol／L Na2SO4＋0．02mol／L NaCl腐蚀介质中交流阻抗谱呈单容抗弧特征，没有出现Warburg阻抗，表明电极表面的腐蚀受电化学反应控制，随Cl^-浓度增加，开始出现Warburg阻抗，表明腐蚀过程由电化学反应控制转化为扩散控制．随Cl^-浓度的增加，容抗弧减小，电荷传递电阻减小，腐蚀速度加快．

Studies on Electrochemical Corrosion Behavior of Cu-50Cr Alloy in Media Containing Cl^-

The electrochemical corrosion behavior of Cu-50Cr alloy prepared by conventional casting in ,solution with different chloride ion concentrations has been investigated by means of potentiodynamic polarization method with Electrochemical Impedance Spectroscopy （EIS）. Results show thai with the increment of chlorine ion concentrations, the corrosion potentials move toward negative direction in different degrees and the corrosion currents increase. Thus, corrosion rates of the prescnt alloy become faster. Cu50Cr alloy has no passivating phenomena in Na2SO4 neutral solution. After chloride ions are added in Na2SO4 neutral solution, there prodtuce passivating phenomena but passivating ranges are very narrow. EIS plots are compcscd of single capacitance loop without Warburg impedance in 0.05 mol/L Na22SO4 solution and 0.05 mol/L Na2SO4 ＋ 0.02 mol/L NaCl solution. The corrosion processes are controlled by electrochemical reactions. With the increment of chloride ion concentrations, the corrosion behavior of the present alloy shows quality of Warburg impedance. The corrosion processes are controlled by electrochemical reaction initially and afterwards controlled by diffusion. With the increase of chloride ion concentrations, the capacitance loop become smaller, and charge transfer resistances become smaller and therefore corrosion rates become faster.