采用动电位极化、电化学阻抗谱技术对超级双相不锈钢 SAF2507在高温高浓度磷酸中的腐蚀行为进行研究。结果表明,SAF2507在64%~72%的85℃磷酸中发生自钝化,且随着浓度增加到80%~88%时,腐蚀电流密度增大,其值仍较小。SAF2507在25~70℃的76%浓度磷酸中,有二次活化现象。随温度升高,SAF2507的反应过程由电化学步骤控制转变为电化学和扩散反应共同控制,且容抗弧半径逐渐减小,极化电阻逐渐减小,耐蚀性能下降。
The corrosion behavior of SAF2507 in high temperature concentrated phosphoric acid has been stu-died with dynamic potential polarization and electrochemical impedance spectroscopy. The results showed that SAF2507 is self-passivation in 64%-72% phosphoric acid at 85 ℃ and the corrosion current density increases when the concentration increases to 80%-88%.It exhibits re-activation phenomenon in 76% phosphoric acid from 25 ℃ to 70 ℃.With the increase of temperature,the controlling reaction process of SAF2507 is from electrochemistry to elec-trochemistry and diffusion reaction.Meanwhile,the capacitive arc radius and polarization resistance decreases gradual-ly,which causes the decay of corrosion resistance.
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