Resistance to Pitting and Chemical Composition of Passive Films of a Fe‐17%Cr Alloy in Chloride‐Containing Acid Solution
Resistance to Pitting and Chemical Composition of Passive Films of a Fe‐17%Cr Alloy in Chloride‐Containing Acid Solution
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DOI：
10.1149/1.2059166
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发表时间：
1994-10
影响因子：
3.9
通讯作者：
W. Yang;D. Costa;P. Marcus
中科院分区：
文献类型：
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作者：
W. Yang;D. Costa;P. Marcus
采用电化学和x射线光电子能谱分析方法研究了Fe-17%Cr合金在含Cl[sup [minus]]溶液（0.5M H[sub 2]SO[sub 4] + 0.3M NaCl）中的耐点蚀性能及其与钝化膜化学成分的关系。钝化膜在无Cl[sup [minus]]或有Cl[sup [minus]]的酸性溶液中老化（电位低于点蚀电位），可提高抗点蚀能力。在0.5M H[sub 2]SO[sub 4] （+500 mV/SHE）条件下形成的钝化膜经过5 min钝化后，具有良好的双层结构（氢氧化物和氧化物）。在极化过程中，钝化膜的厚度（[约]26 ~ 28[埃]）保持恒定。氧化铬的平均阳离子分数随极化时间的延长而增加（极化5 min后为35%，极化24 h后为80%）。时效对抗点蚀性能的有利影响是由于膜/合金界面处氧化铬富集的增强。暴露于Cl[sup[-]]或在含Cl[sup[-]]溶液（0.3M NaCl）中形成的钝化膜与在无Cl[sup[-]]溶液中形成的钝化膜具有相似的成分和厚度，但它们含有Cl[sup[-]]。Cl[sup[-]]离子主要位于氢氧化物层（[约]0.016 mol[中心点]cm[sup[-]3]）。在内部氧化层中发现了极少量的氯[sup [minus]]。«少
The resistance to pitting of a Fe-17%Cr alloy in Cl[sup [minus]]-containing solution (0.5M H[sub 2]SO[sub 4] + 0.3M NaCl) and its relationship with the chemical composition of the passive film have been studied by electrochemical and x-ray photoelectron spectroscopy analyses. Aging of the passive film in the acid solution without or with Cl[sup [minus]] (at a potential below the pitting potential) improves the resistance to pitting. The passive films formed in 0.5M H[sub 2]SO[sub 4] (at +500 mV/SHE) have a bilayer structure (hydroxide and oxide) already well developed after 5 min of passivation. The thickness of the passive film ([approximately]26 to 28 [angstrom]) remains constant during polarization. The average cation fraction of chromium in the oxide increases with increasing polarization time (from 35% after 5 min of polarization to 80% after 24 h of polarization). The beneficial effect of aging on the resistance to pitting is attributed to the enhancement of the chromium oxide enrichment at the film/alloy interface. The passive films exposed to Cl[sup [minus]] or formed in Cl[sup [minus]]-containing solution (0.3M NaCl) have similar composition and thickness as the films formed in Cl[sup [minus]]-free solution, but they contain Cl[sup [minus]]. The Cl[sup [minus]] ions are located mainly inmore » the hydroxide layer ([approximately]0.016 mol [center dot] cm[sup [minus]3]). A very small amount of Cl[sup [minus]] is found in the inner oxide layer.« less