Fe^(3+)水解及其对304不锈钢点蚀行为的影响

Fe^(3+) Hydrolysis and Its Impact on the Pitting Behavior of 304 Stainless Steel

采用动电位极化曲线、电化学阻抗谱、腐蚀形貌分析等方法研究了不同含量Fe^(3+)溶液水解对304不锈钢点蚀行为的影响,并从动力学角度分析了蚀孔生长的过程。结果表明:随Fe^(3+)含量的升高,水解产生的H^+含量升高,使自腐蚀电流密度升高,而溶解氧去极化作用减弱,使得自腐蚀电位负移;由于氢去极化作用,电荷转移电阻逐渐减小,腐蚀速率加快;当Fe^(3+)浓度达到3.0mol/L时,自腐蚀电流密度趋于平稳,金属离子的扩散控制了蚀孔生长,亚稳蚀孔向稳态蚀孔转变存在一个临界电流密度。

Effects of hydrolysis of solutions with different concentrations of Fe3＋ on pitting corrosion behavior of 304 stainless steel were studied by potentiodynamic polarization, electrochemical impedance spectroscopy （EIS） and corrosion morphology analysis. The growth process of pits was investigated through dynamics aspect. The results show that the content of H＋ produced in hydrolysis was increased with the increase of Fe3＋ content, which resulted in the increase of the self corrosion current density, and the depolarization effect of dissolved oxygen decreased, resulting in negative shift of the self corrosion potential. When the content of Fe3＋ reached 3. 0 mol/L or more, the self corrosion current density tended to be stable and level, and diffusion of metal ions controlled the growth of pits, there was a critical corrosion current density when the metastable pits changed into stable pits.