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利用动电位法测定316L奥氏体不锈钢和R1双相不锈钢在C_5H_6O_4-Cl~--NO_3~-水溶液体系中的阳极极化曲线和点蚀电位,探讨了衣康酸(C_5H_6O_4)介质中Cl~-和NO_3~-对点蚀的影响。结果表明:(1)Cl~-浓度[Cl~-]的提高导致不锈钢点蚀电位E_b降低,其关系为E_b=a-blg[Cl~-]。同样条件下,R1不锈钢的点蚀电位比316L不锈钢高300～400mV;(2)在含Cl~-的衣康酸介质中,加入NaNO_3可使不锈钢点蚀电位正移至过钝化电位。在一定温度下,完全抑制点蚀所需的NaNO_3临界浓度因Cl~-含量和钢种而异。
The anodic polarization curve and pitting potential of 316L austenitic stainless steel and R1 duplex stainless steel in C_5H_6O_4-Cl ~ --NO_3 ~ - aqueous solution were determined by potentiodynamic method. The effects of Cl ~ - and NO_3 ~ - the impact of pitting. The results show that: (1) The increase of Cl ~ - [Cl ~ -] leads to the decrease of E_b in stainless steel, which is related to E_b = a-blg [Cl ~ -]. Under the same conditions, the pitting potential of R1 stainless steel is 300 ~ 400mV higher than that of 316L stainless steel. (2) The addition of NaNO_3 in the Cl ~ - containing itaconic acid can shift the pitting potential of stainless steel to the over-passivation potential. At a certain temperature, the critical concentration of NaNO 3 required to completely suppress pitting corrosion varies with Cl ~ - content and steel grade.