HCO3-/CO32-浓度对X70管线钢钝化行为的影响

采用动电位扫描法、循环伏安法研究了X70管线钢在不同浓度的NaHCO₃ /Na₂CO₃ 溶液中的钝化行为。结果表明,材料在该体系中具有明显的钝化现象,随溶液浓度升高,X70钢钝化变得困难。利用Parkins的边界条件,确定了X70钢在1mol/LNaHCO3 +0.5mol/LNa₂CO₃ 溶液中发生应力腐蚀开裂的敏感电位区间为-560～-650mV。X70钢在钝化过程中表面发生的反应比较复杂,电极过程包含Fe的阳极溶解、生成钝化膜、钝化膜的化学溶解三种过程。用X-射线衍射分析了X70钢在活化钝化过渡区表面钝化膜的组成,证实了对电极过程的分析。

Influence of concentration of HCO-3/CO2-3 on passivation behavior of X70 pipeline steel

The passivation behavior of X70 pipeline steel in NaHCO₃ /Na₂CO₃ solution with different concentrations was studied by the potentialdynamic method and the cyclic voltammetry technology. The results show that the passivation phenomena occurr on the material surface and the passivating process become difficult with increase in solution concentration. According to Parkins boundary condition, the sensitive potential range to stress corrosion of X70 steel in 1mol/L NaHCO₃+0 5mol/L Na₂CO₃ solution was determined as -560~-650mV.The reaction occured on the surface of X70 steel were very complicates during the passivation process.The electrode process consisted of three step as:the anodic dissolving of Fe,the formation of passive film and the chemical dissolving of passive film.By XRD technology the composition of the passive film on the surface film of X70 steel formed in the potential range of active- passive transition was analyzed and the electrode process were confirmed.