CAJ | 학술논문

采用浸泡实验,电化学测试和表面分析技术研究了硫酸根离子浓度对铁在稀碳酸氢钠溶液中开路状态和阳极极化行为的影响.在无硫酸根离子及含有少量硫酸根离子的碳酸氢钠溶液中,铁的开路电位约为(-0.225±0.005) V,并呈现钝化状态,其电化学阻抗很大,腐蚀速率较低.在含有较高浓度硫酸根离子的碳酸氢钠溶液中,铁的开路电位为(-0.790±0.010) V并呈现活性溶解状态,其电化学阻抗较小,腐蚀速率较高,同时阳极极化曲线上能观察到活化-钝化转变现象.由于铁在含有较高浓度硫酸根离子的碳酸氢钠溶液中处于活化状态,阳极极化曲线上存在数个电流峰.足够高的硫酸根离子浓度会导致铁表面预先形成或转变而成的氧化膜失效.相比于自然曝氧状态,在除氧条件下较低的硫酸根离子浓度即可引起铁在碳酸氢钠溶液中由钝态向活性溶解态的转变.
채용침포실험,전화학측시화표면분석기술연구료류산근리자농도대철재희탄산경납용액중개로상태화양겁겁화행위적영향.재무류산근리자급함유소량류산근리자적탄산경납용액중,철적개로전위약위(-0.225±0.005) V,병정현둔화상태,기전화학조항흔대,부식속솔교저.재함유교고농도류산근리자적탄산경납용액중,철적개로전위위(-0.790±0.010) V병정현활성용해상태,기전화학조항교소,부식속솔교고,동시양겁겁화곡선상능관찰도활화-둔화전변현상.유우철재함유교고농도류산근리자적탄산경납용액중처우활화상태,양겁겁화곡선상존재수개전류봉.족구고적류산근리자농도회도치철표면예선형성혹전변이성적양화막실효.상비우자연폭양상태,재제양조건하교저적류산근리자농도즉가인기철재탄산경납용액중유둔태향활성용해태적전변.
The effects of sulfate concentration on the open circuit state and anodic polarization behavior of iron in dilute bicarbonate solutions were investigated using immersion tests, electrochemical measurements, and surface analysis techniques. In the absence of sulfate or in the presence of a low concentration of sulfate in dilute bicarbonate solutions, iron was in a passive state, with a corrosion potential of (-0.225±0.005) V. A high electrochemical impedance and low corrosion rate were obtained. No obvious active-passive transition was observed in the anodic polarization curves. In the presence of a high concentration of sulfate in dilute bicarbonate solutions, iron was in an active dissolution state, with a corrosion potential of (-0.790±0.010) V. A low electrochemical impedance, high corrosion rate, and typical active-passive transition in anodic polarization curves were observed and related to the sulfate concentration. In the presence of a high concentration of sulfate, the anodic polarization curves showed current peaks as a result of iron activation by sulfate ions. Sulfate ions of sufficiently high concentration in solutions degraded previously formed oxide layers on iron or transformed oxide layers in bicarbonate solutions. The transition of the open circuit state from passivity to active dissolution occurs at a lower sulfate concentration in a deaerated solution than in an aerated solution.