油罐沉积水中几种离子浓度对孔蚀的影响

Effects of concentration of several ions to pitting corrosion in sedimentary water of oil tank

为了研究油罐沉积水中几种离子对Q235钢局部腐蚀的影响,通过CHI660电化学工作站测滞后环的方法进行分析。结果表明:在研究范围内,局部腐蚀最严重时各离子质量浓度为C1-10 g/L、SO2-41 g/L、HCO-30.75g/L、Ca2+0.35 g/L、Mg2+0.2 g/L。Cl-为10 g/L时Q235钢的点蚀敏感性最大,大于10 g/L时,随着Cl-质量浓度增大,Q235钢发生点蚀的倾向变小;SO2-4质量浓度为1 g/L时Q235钢点蚀敏感性最大,大于1 g/L时,随着SO2-4质量浓度增大,Q235钢发生点蚀的倾向变小;HCO-3质量浓度为0.75 g/L时Q235钢最容易产生点蚀,HCO-3含量继续增大,大于0.75 g/L时,点蚀的倾向减小。Ca2+质量浓度为0.35 g/L时Q235钢最容易产生点蚀,Ca2+含量继续增大,大于0.35 g/L时,点蚀的倾向减小;Mg2+质量浓度为0.2 g/L时,Q235钢最容易产生点蚀,Mg2+含量继续增大,含量大于0.2 g/L时,点蚀的倾向减小。

To study effects of concentration of several ions in sedimentary water of oil tank to pitting corro- sion on Q235 steel, hysteretic loops were measured by the electrochemical station CHI660. Results indi- cated that when the Q235 steel was most serious pitting-corroded, the concentrations of each ions were C1- 10 g/L, S024- 1 g/L, HCOf 0.75 g/L, Ca2＋ 0.35 g/L, and Mg2＋ 0. 2 g/L. Q235 steel was most likely pitting-corroded on those ion concentrations. With the concentrations higher, than those mentioned above, pitting-corrosions tended to decrease. Q235 steel was most likely pitting-corroded on 10 g/L of C1- concentration,with the increase of CI-, more than 10 g/L, pitting-corrosions tended to decrease. With the increasing of S024- , more than 1 g/L, pitting on Q235 steel decreased. With HCO3- continued to increase, more than 0. 75 g/L, pitting reduced. It was easy to produce pitting when Ca2 ＋ was 0.35 g/L, with the increasing of Ca2＋ , more than 0.35 g/L, pitting declined. It was very easy to bring about pitting on Q235 steel when Mg2＋ was O. 2 g/L, more than O. 2 g/L,pitting gradually reduced.