Atomic emission spectroelectrochemistry was used to monitor the elemental dissolution of two stainless steels during transpassive polarization. A 304LN stainless steel (X2 CrNiN 18-10) was compared with a 3.5 wt% Si rich stainless steel (X1 CrNiSi 18-15-4) so as to elucidate the effect of Si on the dissolution mechanism. The enrichment in Si shifted the cathodic reaction to lower potentials explaining that in hot and concentrated nitric acid containing oxidizing species, 304LN SS corrodes more rapidly due to the transpassive break of passivity, while the 3.5 wt% Si SS remains passive. However, when polarized into the transpassive domain, preferential grain boundary corrosion was observed for the 304LN but not for the 3.5 wt% Si SS, despite having similar current densities. Congruent alloy dissolution was observed in the transpassive domain with the stoichiometry of Fe(III), Cr(VI) and Ni(II) yielding a faradaic yield of 100% at early times. For longer times, with the 304LN, the faradaic yield drop to 70% indicative of intergranular dissolution in which the cations released in the intergranular space were not detected by the ICP-AES. Transmission electron microscopy coupled with energy dispersive spectroscopy showed that the interface of the 3.5 wt% Si SS enriches in Cr during a polarization in the transpassive domain of the steel. No similar enrichment was detected for the 304LN.

原子发射光谱电化学用于监测两种不锈钢在无源极化过程中的元素溶解。将304LN不锈钢（X2 CrNiN 18-10）与3.5 wt％的富硅不锈钢（X1 CrNiSi 18-15-4）进行比较，以阐明Si对溶解机理的影响。Si的富集将阴极反应转移到较低的电位，这说明在热的浓硝酸中，氧化性物质中，304LN SS由于无源性的穿透性破坏而腐蚀更快，而3.5 wt％的Si SS保持钝化。但是，当极化进入穿越型磁畴时，尽管电流密度相似，但对304LN观察到了优先的晶界腐蚀，但对3.5 wt％的Si SS却没有观察到。在化学计量学上，Fe（III），Cr（VI）和Ni（II）的化学计量学在贯穿钝化域中观察到同合金溶解，早期产生的法拉第产率为100％。在更长的时间内，使用304LN时，法拉第产率下降到70％，表明晶间溶解，其中ICP-AES无法检测到在晶间空间中释放的阳离子。透射电子显微镜与能量色散光谱法相结合表明，在钢的透射钝化区极化期间，3.5 wt％Si SS的界面在Cr中富集。304LN没有检测到类似的富集。法拉第收率下降到70％，表明晶间溶解，其中ICP-AES未检测到在晶间空间中释放的阳离子。透射电子显微镜与能量色散光谱法相结合表明，在钢的透射钝化区极化期间，3.5 wt％Si SS的界面在Cr中富集。304LN没有检测到类似的富集。法拉第收率下降到70％，表明晶间溶解，其中ICP-AES未检测到在晶间空间中释放的阳离子。透射电子显微镜与能量色散光谱法相结合表明，在钢的透射钝化区极化期间，3.5 wt％Si SS的界面在Cr中富集。304LN没有检测到类似的富集。