亚临界汽包炉全挥发处理环境中氯离子腐蚀行为试验分析

摘要

Under all volatile treatment (AVT)working conditions of subcritical drum boiler,in high temper-ature anaerobic alkaline environment,the effect of Cl- on passive film on metal surface when Cl- was con-centrated in the inner surface of the wall tube (the side facing the fire)was investigated,by electrochemical online test and the surface topography images.The results show that,when the Cl- concentration is equal or lower than 3.00 mg/L,the metal film resistance is large and the metal film is complete.While when the Cl- concentration is higher than 3.00 mg/L,the metal film resistance drops sharply,and pitting corrosion occurs on the metal surface.Moreover,the corrosion on the metal surface gets severe with the increasing Cl- concentration.%模拟亚临界汽包炉全挥发处理(AVT)环境，在高温无氧碱性条件下，采用电化学和试片表面金相分析方法，对氯离子(Cl－)在水冷壁管内表面(向火侧)发生浓缩时的腐蚀情况，包括不同Cl－质量浓度对金属表面钝态膜的影响，进行了研究.结果表明：当 Cl－质量浓度≤3．00 mg/L时，金属膜电阻较大，金属膜完整；当Cl－质量浓度＞3．00 mg/L时，金属膜电阻急剧减小，金属表面出现点蚀，且随Cl－质量浓度增大，金属表面腐蚀加重.