20#碳钢在HCO3^-和Cl^-混合溶液中的点蚀行为研究

Study on the Pitting Corrosion of 20#Steel in HCO3^- and Cl^- Mixed Solution

采用动电位极化方法研究了在0.5 mol/L NaHCO3+0.002 mol/L NaCl溶液中,20#碳钢的破钝电位和维钝电位区间,使用钝化+电流控制方法研究20#碳钢的点蚀行为和腐蚀机理。试验结果表明:在该溶液体系中,20#碳钢试样具有一定钝化效果,钝化电位区间为-148〜908 mV;点蚀坑的尺寸、深度和数量均随试验时间的增加而增加;Cl^-对钝化膜具有破坏作用,腐蚀反应机理为阳极溶解+膜破裂机制。采用HCO3^-与Cl^-混合溶液结合电化学方法,利用电化学腐蚀进行点蚀试样制备具有可行性。

Potentiodynamic polarization method were used to study the break passive potential and the passive potential of 20#steel in the solution,0.5 mol/L NaHCO3+0.002 mol/L NaCl.Passivation and current control methods were applied to study the pitting mechanism of 20#steel.The results showed that the 20#steel sample had a certain passivation effect in the testing solution system,and the passive potential range was -148 mV^908 mV.For the test of 20#steel in solution,the size,depth and number of pitting increased with the increase of the test time.Cl^-had a destructive effect on the passive film.The corrosion mechanism was anode dissolution and film rupture mechanism.It was feasible to use HCO3^- and Cl^- mixed solution in combination with electrochemical method to prepare pitting sample by electrochemical corrosion.