酸性氯离子溶液中硫代硫酸根对800合金腐蚀机理

Corrosion Mechanism of Alloy 800 in Acidic Solution Containing Thiosulfate and Chloride Ions

综合采用动电位极化曲线、电化学噪声(EN)技术和3D显微镜相结合,研究了800合金在酸性模拟缝隙水化学中的腐蚀行为,分析了S_2O_3^(2-)浓度对合金在酸性Cl^-环境下腐蚀过程的影响与机理.实验结果表明:在含有Cl^-和S_2O_3^(2-)的酸性溶液中,800合金表面为活性溶解状态,腐蚀速度较快.酸性环境中,极微量的S_2O_3^(2-)对800合金在Cl^-溶液中的腐蚀没有显著影响;随着S_2O_3^(2-)浓度的增加,极化曲线向电位较负方向偏移,相同电位条件下阳极电流密度显著增加,阴极电流略微增大.EN测试结果表明,酸性Cl^-溶液中加入0.075,mol/L S_2O_3^(2-)后噪声电阻降低了约2个数量级,电流标准偏差增加了约2个数量级,这是由于S_2O_3^(2-)的加入加速了合金的阳极溶解过程.

Polarization curves,combined with electrochemical noise（EN）,3D microscopy,were used to study the corrosion behavior of Alloy 800 in simulated crevice water chemistry,and the effect of the concentration of thiosul-fate in acidic solution containing chloride ions on corrosion resistance was analyzed. The results show that the surface of Alloy 800 is activated and dissolved in the acidic solution containing chloride and thiosulfate ions,and the corro-sion rate is fast. In the acidic environment,the trace amount of reduced thiosulfate ionhas no significant effect on the corrosion of the Alloy 800 in the solution containing chloride ion. With the increase of the concentration of thiosulfateion,the polarization curve is shifted to the negative direction. And under the same potential conditions,the anode current density increases significantly. EN results show that the noise resistance is reduced by two orders ofmagnitude,and the current standard deviation is increased by two orders of magnitude after adding 0.075 mol/L thi-osulfate ion to the acidic solution containing chloride ion. This mainly due to the addition of thiosulfate ion to acceler-ate the process of alloy anode corrosion.