钝化预处理对316L不锈钢在漂液中电化学腐蚀性能的影响

Effect of passivation pretreatment on electrochemical corrosion of 316 L stainless steel in bleaching liquid

采用电化学测试、SEM分析等方法,研究了316 L不锈钢在质量分数为30%的浓硝酸溶液及98%硫酸+20 g/L硝酸钾混合液两种钝化剂预处理后的特性,以及在ClO2漂液中的电化学抗腐蚀性能。结果表明,316 L不锈钢在25℃、30%硝酸介质中处理30 min时抗点蚀能力ΔE可达到773 mV,钝化效果较好。EIS图谱表明:316 L不锈钢在ClO2漂液中具有双容抗弧特征,钝化处理容抗弧半径较未钝化的增大,处理后的316 L不锈钢在60℃出现了Warburg阻抗;钝化膜的外层电阻和内层电阻均比未钝化的大。经钝化处理后的316 L不锈钢在ClO2漂液中的受腐蚀速率较未钝化的降低近一半,与钛材相比耐蚀性较差,但能在一定条件下起到减缓腐蚀的作用。

The characteristics of 316 L stainless steel which was pretreated under 30 %（mass fraction） of concentrated nitric acid and 98 % H2SO4＋20 g/L KNO3 mixture respectively and the electrochemical corrosion of 316 L stainless steel in chlorine dioxide bleaching liquid were investigated by electrochemical testing and SEM analysis.From the results it showed that the pitting corrosion resistance ΔE of 316 L stainless steel could be up to 773 mV in the media of 25 ℃,30 % HNO3 for 30 minutes.EIS spectra showed that 316 L stainless steel in chlorine dioxide bleaching liquid had double capacitive reactance arcs characteristics;the radius of capacitance reactance arc increased than those without passivation;the treated 316 L stainless steel at 60 ℃ appeared Warburg impedance;the outer and inner resistances of the passive film was larger than those without passivation.The corrosion rate of 316 L stainless steel by passivation in chlorine dioxide bleaching liquid lowered than the untreated nearly half,but the corrosion resistance is poor compared with titanium,and it can slow corrosion under certain conditions.