pH与温度对2205DSS在盐卤中的孔蚀影响

INFLUENCE OF pH AND TEMPERATURE ON PITTING CORROSION OF 2205DSS IN BITTERN

利用电化学方法、交流阻抗技术、失重法及金相显微术研究了pH与温度变化对2205DSS在盐卤中耐孔蚀行为的影响.结果表明:随着卤水pH值的增大,2205DSS耐孔蚀性能先略微增强、然后减弱;根据实际制盐工艺条件,卤水的pH值应适当控制在8.7或8.8以内;随温度升高,2205DSS基体抵抗孔蚀能力明显下降;试样在盐卤水介质中的电极反应是不可逆的,其腐蚀反应既受活化极化控制,又受溶液扩散控制.

The influence of pH value and temperature steel 2205DSS in bittern was investigated by means of on the resistance to pitting corrosion of stainless electrochemical methods and electrochemical im- pedance spectra in this paper. The weight-loss data for 2205DSS in bittern solution were measured in the solutions. Pitting corrosion images were observed by metalloscope and the surface roughness was analyzed. The results showed that the resistance to pitting corrosion for 2205 DSS in bittern solution was enhanced slightly first and then descreased largely with increasing the value of pH. Therefore it is proposed that the pH value should be controlled less than 8.7 or 8.8 for the practical salt making process. But the resist- ance to pitting corrosion decreased with rising up temperature rapidly. The electrode reaction was irreversi- ble and controlled by both activation polarization as well as the diffusivity of the bittern medium.