铝酸钠溶液中 Na2 S 对 Q235 钢腐蚀的影响

目的研究在含S2-的铝酸钠溶液中Q235钢的腐蚀行为。方法模拟生产条件配制种分母液,采用盐雾腐蚀实验与SEM和EDS分析技术,结合腐蚀质量损失动力学方程与极化曲线,研究Na2S质量浓度与时间对Q235钢腐蚀行为的影响。结果腐蚀产物元素主要为O,S,Al,Fe。在铝酸钠溶液中,基体的表面会覆盖一层Al2O3保护膜,可以阻碍溶液中的硫离子穿透到基体表面,对基体起到一定的保护作用。因此腐蚀初期及低质量浓度下,腐蚀速率缓慢;但随着质量浓度的增加、腐蚀时间的延长,保护膜被破坏,S2-穿过保护膜与基体反应,生成硫化物加速了腐蚀速率;当S2-质量浓度增加到6 g/L,腐蚀时间为9 d时,硫化物被氧化成具有较稳定结构的氧化物,腐蚀被抑制。结论在铝酸钠溶液中,S2-质量浓度及腐蚀时间对腐蚀有一定的促进作用,但当腐蚀时间及S2-质量浓度达到一定值时,腐蚀速率呈现减小的趋势,腐蚀被抑制。

Effect of Na2S in Sodium Aluminate Solution on the Corrosion Behavior of Q235 Steel

Objective To study the corrosion behavior of Q235 steel in the S2--containing sodium aluminate solution. Methods The production conditions were simulated to prepare the mother liquor. Salt spray corrosion method together with SEM and EDS analysis technology, combined with the corrosion weight loss dynamics equation and polarization curve were used to study the effects of the Na2 S concentration and time on the corrosion behavior of Q235 steel. Results The elements of corrosion products were mainly O, S, Al and Fe. In sodium aluminate solution, the surface of the substrate was covered with a layer of Al2 O3 protective film, which could hinder the penetration of sulfur ions in the solution to the substrate surface, and play a role in the protection of the matrix. Therefore, in the early corrosion stage and at low concentrations, the corrosion rate was low, but with the increase of the concentration and the prolonged corrosion time, the protective membrane was damaged, S2- passed through the protective film and reacted with the substrate, generating sulphide which accelerated the corrosion rate. When the S2- mass concentration increased to 6 g / L and the corrosion time was 9 d, sulfide was oxidized to oxide with a relatively stable structure, the corrosion was inhibited. Conclusion In sodium aluminate solution, S2- concentration and corrosion time had a certain promoting effect of corrosion , but when the corrosion time and S2- concentration reached a certain value, the corrosion rate showed a decreasing trend, the corrosion was inhibited.