新型合金耐蚀钢筋Cr10Mo1的阴极行为及其阻抑机制

Cathodic behaviour of new alloy corrosion-resistant steel Cr10Mo1 and its depression mechanism

应用阴极动电位极化法研究比较了预先钝化合金耐蚀钢筋Cr10Mo1和普通碳素钢筋在不同Cl-浓度(0,0.2,0.6,1.0 mol/L)的模拟混凝土孔溶液(p H 13.5)中的阴极反应行为,结合Mott-Schottky方法测试钢筋钝化膜导电性能及XPS方法分析钝化膜组成结构,分析了2种钢筋阴极行为存在差异的原因,揭示了合金耐蚀钢筋阴极行为阻抑机制.结果表明:在相同Cl-浓度下,合金耐蚀钢筋阴极反应速率总是低于普通碳素钢筋,随Cl-浓度增大,这一差异更加明显.相比普通碳素钢筋,合金耐蚀钢筋钝化膜具有更低的载流子密度,更有利于阻碍阴极反应电子传递.Cr氧化物作为合金耐蚀钢筋钝化膜不同于普通碳素钢筋的关键成分,高浓度氯盐下仍可保持稳定并维持钝化膜层密实完整,继续阻碍钢筋阴极反应电子传递.

Cathode reaction behaviours of previously passivated alloy corrosion-resistant steel Cr10 Mo1 and plain carbon steel in simulated concrete pore solutions（ p H 13. 5） with different chloride contents（ 0,0. 2,0. 6,1. 0 mol / L） were investigated by a cathodic potentiodynamic polarization method,combined with measurements of the conduct electricity and chemical composition of passive films by the Mott-Schottky approach and X-ray photoelectron spectroscopy（ XPS）,respectively.Based on these,the reasons for differences between the two steels＇ cathodic behaviours were analyzed,and the mechanisms responsible for the cathodic depression of the alloy corrosion-resistant steel were revealed. The results showthat the alloy corrosion-resistant steel has a lower cathode reaction rate than plain carbon steel at the same chloride level,and the difference is more significant with the increase of chloride contents. Passive films formed on the alloy corrosion-resistant steel have lower carrier concentration than those on plain carbon steel,which is more favorable to hinder electron transfer in cathodic reaction. Cr oxides,as the key components which just make the differences between passive films on the alloy corrosion-resistant steel and plain carbon steel,can still remain stable and maintain dense and sound passive film layers for the alloy corrosion-resistant steel under high-concentration chlorides,continuously hampering electron transfer in the cathodic reaction for the steel.