湿热海洋大气中SO2污染对Q235B钢腐蚀行为的影响

 以NaCl和NaHSO3为介质，采用干/湿周浸加速腐蚀试验、腐蚀失重分析、XRD、SEM等，研究了湿热海洋大气中SO2对Q235B钢腐蚀行为的影响。结果表明，SO2污染使Q235B钢的腐蚀明显加重。污染前后，Q235B钢的腐蚀过程均遵循幂函数W＝Atn]的分布规律，腐蚀产物均由非晶和少量Fe3O4、α-FeOOH、β-FeOOH、γ-FeOOH晶体组成，但参数A、]n]值和晶体数量并不相同。Cl－和SO2在腐蚀过程中具有协同作用，但作用机理不同。Cl－会阻止腐蚀产物吸附，并促使其脱落，进而阻止保护性锈层形成；而SO2在酸化过程中会与钢基体和锈层反应，进而破坏锈层结构，加剧钢的腐蚀。SO2还能抑制β-FeOOH并促进α-FeOOH的生成，进而抑制Cl－的破坏作用并改善锈层的稳定性；但随锈层增厚，SO2的抑制作用减弱，内锈层随之变疏松。

Effect of SO2 pollution on corrosion behavior of Q235B steel in hot and humid marine atmosphere

The effect of SO2 on the corrosion behavior of Q235B steel in simulated marine atmosphere was investigated by XRD,SEM,mass loss analysis and a wet/dry alternate immersion corrosion test using 0.1 mol/L NaC1 solution and 0.1 mol/L NaC1 +0.01 mol/L NaHSO3 solution.The results indicate that SO2 pollution significantly increases the corrosion depth of Q235B steel.The corrosion processes of Q235B steel show a good agreement with the power function of W=Atn,and the corrosion products are mainly composed of amorphous phase and a small amount crystals of Fe3O4、α-FeOOH、β-FeOOH、γ-FeOOH.However,the values of parameters A,n and the amount of each crystal are changed before and after SO2 pollution.SO2 and Cl-are synergies in the corrosion process of Q235B steel,but their mechanisms of action are different.C1 can prevent the adsorption of corrosion products,and promote them falling,thereby inhibiting the formation of protective rust layer.While SO2 will react with the steel substrate and rust layer during its acidification process,which will lead to the destruction of rust layer structure and the deterioration of corrosion resistance of the steel.In addition,SO2 can inhibit the formation of β-FeOOH and promote the formation of αt-FeOOH generated,thereby inhibit the role of C1-and improve the stability of the rust layer.However,as the rust layer thickness increases,the inhibition of SO2 reduces,and the inner rust layer becomes loose.