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用动电位极化、EIS和XPS等方法研究了应变作用下Q235碳钢在Na HCO3+Na Cl溶液中的孔蚀行为。结果表明:在0.2 mol·L-1Na HCO3+0.01 mol·L-1Na Cl溶液中,与无应变试样相比,8%的应变导致Q235碳钢的孔蚀电位Eb升高;随溶液Cl-浓度升高,应变试样的Eb逐渐降低,当Cl-浓度增大到0.1 mol·L-1时,应变试样的Eb值降低到与无应变试样相同的水平。另一方面,应变导致Q235钢钝化膜中Fe3+/Fe2+比值减小,膜阻抗降低,电荷转移电阻变小,钝化膜的稳定性有所降低。在实验条件下应变导致Eb升高的现象归因于溶液中HCO3-的存在,应变促进钢表面的阳极溶解,进而促进了HCO3-在表面的优先吸附,一定程度上抑制了Cl-促进孔蚀的作用。随溶液中HCO3-/Cl-的比值降低,应变导致的Eb值变化逐渐减小直至消失。
Pitting corrosion behavior of Q235 carbon steel in Na HCO3 + Na Cl solution under strain was studied by potentiodynamic polarization, EIS and XPS. The results show that in 0.2 mol·L-1Na HCO3 + 0.01 mol·L-1Na Cl solution, the strain of 8% increases the pitting potential Eb of Q235 carbon steel compared with the unstrained sample. With the increase of Cl- When the concentration of Cl- increased to 0.1 mol·L-1, the Eb value of the strain decreased to the same level as that of the unstrained specimen. On the other hand, the strain resulted in the decrease of Fe3 + / Fe2 + ratio in Q235 steel passivation film, the decrease of film resistance, the decrease of charge transfer resistance and the decrease of the stability of passivation film. Under the experimental conditions, the strain caused by the increase of Eb is attributed to the presence of HCO3- in the solution. The strain promotes the anodic dissolution on the steel surface, which in turn promotes the preferential adsorption of HCO3- on the surface and to a certain extent inhibits Cl- Role. As the ratio of HCO3- / Cl- in the solution decreases, the strain-induced change in Eb value decreases until it disappears.