The Effects of pH Values on Functional Mechanisms of Nitrite Anions for Q235 Carbon Steels in 0.01 mol L-1 NaNO2-HCl Solutions
The Effects of pH Values on Functional Mechanisms of Nitrite Anions for Q235 Carbon Steels in 0.01 mol L-1 NaNO2-HCl Solutions
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DOI：
10.21577/0103-5053.20190070
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发表时间：
2019-08
影响因子：
1.4
通讯作者：
Yong Zhou;Pei Zhang;Huiju Huang;Jinping Xiong;Fuan Yan
中科院分区：
文献类型：
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作者：
Yong Zhou;Pei Zhang;Huiju Huang;Jinping Xiong;Fuan Yan
研究了Q235碳钢在不同pH值的0.01 mol L NaNO 2-HCl溶液中，pH值对亚硝酸根（NO2）作用机理的影响。在pH 1和pH 2的溶液中，Q235钢表现出活化的电化学行为，Q235钢表面以均匀腐蚀（UC）为主。NO2的存在并不影响其电化学行为和腐蚀类型，而只是加速了Fe的阳极氧化反应。在pH 3和pH 4的溶液中，Q235钢呈现活化-钝化转变的电化学行为，Q235钢表面发生晶间腐蚀（IGC）。NO2还原的阴极反应导致电化学行为由活化向钝化转变，腐蚀类型由UC向IGC转变。在pH 5和pH 6溶液中，Q235钢表现出自钝化-点蚀的电化学行为，Q235钢表面出现点蚀（PC）。NO2的强氧化性是Fe和NO2共同作用下Q235表面形成γ-Fe 2 O3钝化膜的关键。
For Q235 carbon steels in 0.01 mol L NaNO2-HCl solutions with different pH values, the effects of pH values on the functional mechanisms of nitrite anions (NO2) were studied. In the pH 1 and pH 2 solutions, the Q235 steels showed the electrochemical behavior of activation, and uniform corrosion (UC) was the main corrosion type on the Q235 surface. The presence of NO2 did not affect the electrochemical behavior and the corrosion type but only accelerated the anodic reaction of Fe oxidation. In the pH 3 and pH 4 solutions, the Q235 steels presented the electrochemical behavior of activation-passivation transition, and intergranular corrosion (IGC) occurred on the Q235 surface. The cathodic reaction of NO2 reduction resulted in the transition of electrochemical behavior from activation to passivation and the change of corrosion type from UC to IGC. In the pH 5 and pH 6 solutions, the Q235 steels exhibited the electrochemical behavior of self passivation-pitting, and pitting corrosion (PC) was present on the Q235 surface. The strong oxidability of NO2 played a critical role in the formation of γ-Fe2O3 passive film on the Q235 surface under the combined action of Fe and NO2.