Q235-304L电偶对在Na_2S溶液中的电偶腐蚀行为研究

GALVANIC CORROSION BEHAVIORS OF Q235-304L COUPLE IN Na_2S SOLUTION

用电化学法和浸泡法研究了Q235-304L电偶对在3种不同浓度的Na2S溶液中的电偶腐蚀行为,用SEM观察试样的表面形貌.结果表明:在3种溶液中Q235钢的阳极过程均为混合控制,而304L的阴阳极过程均为电化学控制;偶接后Q235钢表面阳极金属的溶解过程与阴极过程同时进行,其阳极溶解电流大于电偶电流值;电偶腐蚀效应随阴阳极面积比的增大而增大;随着S2-浓度的升高,电偶对中Q235钢的腐蚀速率减小,电偶腐蚀效应也随之降低.

Galvanic corrosion behaviors of Q235 - 304L couple with various cathode/anode area ratios in three different concentrations of Na2S solutions were studied by the potentiodynamic polarization curves, galvanic method and immersion test. Surface morphologies of the samples were also analyzed by SEM after rust cleaning. The results showed that： both the cathodic and anodic processes of 304L were controlled by the electrochemical step, while the anodic process of Q235 exhibited an apparent characteristics of activation - diffusion mixed control ; a cathodic process as well as an anodic process took place on the surface of Q235 after coupled and the dissolution current of Q235 was much more above the galvanic current got by galvanic corrosion method;as the area ratio increases, the galvanic effect increases; and with the elevation of the concentration of S^2- , the corrosion rate of Q235 decreased, so did the galvanic effect.