NaCl溶液中介质流动及Cr元素对低合金钢腐蚀行为的影响

Influence of Medium Flow and Cr Element on Corrosion Behavior of Low Alloy Steel Immersed in NaCl Solution

对碳钢和含Cr低合金钢在静态和流动3.5%NaCl溶液中的腐蚀行为进行研究。对两种腐蚀环境下实验钢的腐蚀失重进行了比较,并利用动电位极化曲线、SEM、EMPA、XRD和XPS,对实验钢的电化学特性和表面锈层的特征进行研究。结果表明,在形成腐蚀产物后,含Cr实验钢在流动环境中的腐蚀失重显著低于碳钢,并且实验钢在流动环境中的腐蚀失重高于静态环境。Cr元素富集于内锈层中参与内锈层中腐蚀产物的形成与转化,提高了内锈层的致密性,抑制了去极化剂向基体表面的扩散,从而抑制了阴极反应的进行。Cr元素在内锈层的富集提高了含Cr钢在流动NaCl溶液中的耐蚀性。

The corrosion behavior of carbon steel and Cr containing steel immersed in stagnant and flowing 3.5%NaCl solution was investigated.In the two corrosion conditions,the corrosion mass loss of experimental steels were compared respectively.The electrochemical performance of experimental steels and the characteristic of rust layers on the experimental steels were analyzed by potentiodynamic polarization curve,SEM,EMPA,XRD and XPS.The results show that the corrosion mass loss of Cr containing steel is significantly lower than that of carbon steel in flowing environmnet,when the corrosion product forms on the steels.In addition,the corrosion mass loss of the experiemnt steel in flowing environmnet is obviously higher than that in stagnant environmnet.Cr enriches in the inner rust layer,which can incorporate into the formation and transformation of corrosion products in the layer.The compactness of the inner rust layer improves.The diffusion of Cr containing steel enhanced by concentration of Cr in the inner rust layer,thereby,the diffusion of depolarizer to substrate surface is inhibited,and the cathodic reaction is suppressed.The enrichment of Cr in the inner rust layer can enhance the corrosion resistance of Cr containing steel immersed in flowing NaCl solution.