应变作用下Q235碳钢在NaHCO_3+NaCl溶液中的孔蚀行为  

Pitting Corrosion Behavior of Q235 Carbon Steel in NaHCO_3+NaCl Solution under Strain

作　　者：李阳恒 左禹[1] 唐聿明[1] 赵旭辉[1] 

机构地区：[1]北京化工大学材料科学与工程学院,北京100029

出　　处：《中国腐蚀与防护学报》2016年第3期238-244,共7页Journal of Chinese Society For Corrosion and Protection

基　　金：国家自然科学基金项目(51171014和51210001)资助

摘　　要：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。The effect of strain on the pitting behavior of Q235 carbon steel in solutions of Na HCO_3＋NaCl was studied by means of potentiodynamic polarization measurement, EIS and XPS. The results show that in a solution of 0.2 mol·L^-1NaHCO_3＋0.01 mol·L^-1Na Cl, a strain of 8% leads to an obvious increase of the pitting potential E_b of Q235 steel, but as the Cl-concentration increased, the difference between the Ebvalues of strain and strain free samples decreased. When the Cl-concentration increased to 0.1 mol·L^-1, the difference of Ebvalues disappeared. Besides, strain caused lower impedance, smaller charge transfer resistance Rctand decreased the ratio Fe^3＋/Fe^2＋ in the passive film, thereby reduced the stability of passive film. The phenomenon that strain caused the increase of E_b was attributed to that the strain promoted the anodic dissolution of Fe which in turn promoted the preferential adsorption of HCO_3^- on the surface, as the result the harmful effect of Cl^- on the passive film was inhibited. As the ratio HCO_3^-/Cl^- in the solution decreased, the effect of HCO3-decreased and finally disappeared.

关 键 词：Q235钢 孔蚀 应变 HCO3- 钝化膜 

分 类 号：TG172[金属学及工艺—金属表面处理]