高含Cl^(-)环境下pH值对904L不锈钢腐蚀行为的影响

Effect of pH value on the Corrosion Behavior of 904L Stainless Steel Under High Cl^(-) Concentration Environment

为了获得904L不锈钢在高含Cl^(-)不同pH值环境下的耐蚀性能,通过循环极化曲线、电化学阻抗谱、奥林巴斯共聚焦显微镜、扫描电子显微镜(SEM)及能谱分析(EDS)研究了904L奥氏体不锈钢在不同pH值的100 g/L NaCl溶液中的腐蚀行为。结果表明:904L不锈钢的耐蚀性随着pH值的升高而提高,EIS由2个容抗弧组成,容抗弧半径随着pH值升高而增大,且容抗均在一个数量级;较低的pH值条件能够增强Cl^(-)对钝化膜的破坏性,随着pH值的降低,材料的钝化区范围降低,当pH=2时,材料表面出现轻微点蚀。

For improving the corrosion resistance of 904L stainless steel under high Cl^(-) concentration environment with different pH values condition,the corrosion behavior of 904L austenitic stainless steel in 100 g/L NaCl solution at different pH values was studied by cyclic polarization curves,electrochemical impedance spectroscopy,Olympus confocal microscopy,scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).Results showed that the corrosion resistance of 904L stainless steel increased with the increase of pH value,EIS consisted of two capacitive reactance arcs,and the radius of capacitive reactance arc increased with the increase of pH value,and the capacitive reactances were all in the same order of magnitude.Meanwhile,lower pH value conditions could enhance the destructive effect of Cl^(-)on the passive film.With the decrease of pH value,the range of passive region of the material decreased.When the pH=2,slight pitting occurred on the surface of the material.