NH4+ Generation: The Role of NO3? in the Crevice Corrosion Repassivation of Type 316L Stainless Steel
NH4+ Generation: The Role of NO3? in the Crevice Corrosion Repassivation of Type 316L Stainless Steel
复制标题
NH4 的生成：NO3 的作用？
DOI：
10.1149/2.0501910jes
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发表时间：
2019
影响因子：
3.9
通讯作者：
Hara Nobuyoshi
中科院分区：
文献类型：
--
作者：
Aoyama Takahito;Sugawara Yu;Muto Izumi;Hara Nobuyoshi
研究了NO3-在316L不锈钢缝隙腐蚀再钝化中的作用。在缝隙腐蚀测试中，溶液从1 M NaCl改为NaCl-NaNO 3。NO3-导致完全再钝化，在2 M KNO 3中恒电位极化后，通过离子色谱分析在缝隙溶液中检测到NH 4+。发现缝隙腐蚀的再钝化分两步进行。在第一步中，缝隙内的估计电流密度从约1000 V逐渐减小。5 mA cm− 2至约5 μA cm− 2。之后，电流密度突然下降到小于0.1 μA cm-2。根据缝隙内模拟酸性溶液（pH 0.2）中的动电位极化和缝隙腐蚀形态的原位观察，第一步被认为是由NO3 −抑制活性溶解产生的。NH 4+的产生导致pH升高，进一步抑制活性溶解，然后发生再钝化。
The role of NO 3− in the repassivation of crevice corrosion of Type 316L stainless steel was investigated. In crevice corrosion tests, the solution was changed from 1 M NaCl to NaCl-NaNO 3. NO 3− led to complete repassivation, and after potentiostatic polarization in 2 M KNO 3, NH 4+ was detected in the crevice solution by ion chromatography analysis. Repassivation of the crevice corrosion was found to take place in two steps. In the first step, the estimated current density inside the crevice gradually decreased from ca. 5 mA cm− 2 to ca. 5 μA cm− 2. After that, the current density suddenly decreased to less than 0.1 μA cm− 2. From the potentiodynamic polarization in acidic solutions simulated inside the crevice (pH 0.2) and in situ observations of the crevice corrosion morphology, the first step was thought to be generated by the suppression of active dissolution by NO 3−. It would appear that the generation of NH 4+ results in a pH increase and the further suppression of active dissolution, and then repassivation occurs.