钕在离子液体中的阳极行为及机理
发布时间：2018-10-04 18:55
【摘要】：金属钕(Nd)是较重要的稀土金属之一,因为其独特的4f电子层结构,所以一些Nd及含Nd合金具备了特殊的光、电、磁和催化性能,在现代工业中应用极其广泛,其主要应用领域有永磁体材料、高级金属合金以及添加剂等等。然而在实际应用中,往往需要对Nd及其合金进行表面处理,以提高其耐蚀性能。由于Nd的活性高,表面处理的难度极大,因此寻找适合金属Nd及其合金特点的表面处理新介质,并开展相关的应用及机理的研究,是表面科学与技术领域中重要的课题。离子液体是一种新型溶液,是除水和有机溶剂之外的第三大溶剂,在活性金属的表面工程领域中具有独特的应用前景。本文主要研究了Nd在2：1酸性AlCl3-氯化1-甲基-3-乙基咪唑(AlCl3-EMIC)、0.8：1碱性AlCl3-EMIC以及1-丁基-1-甲基吡咯烷双(三氟甲磺酰)亚胺盐([BMP]Tf2N)离子液体中的阳极行为。采用循环伏安法测定了三种离子液体的电位窗；通过线性伏安扫描、恒电流极化以及恒电位极化研究了Nd在离子液体中阳极溶解,利用恒电流溶解计算了Nd的溶解价态；最后采用SEM考察了恒电流溶解之后Nd的表面形貌,并通过EDS和原位Raman进行Nd表面成分的分析。本文的研究结果表明,在2：1酸性AlCl3-EMIC中,当阳极电流密度≥5mA/cm2时,在Nd和离子液体的界面会形成粘性膜。粘性膜的产生是由于高粘度的溶解产物Nd(Ⅲ)在Nd和离子液体界面聚集的结果。粘性膜的产生有着“钝化—活化”的作用,在该作用下,Nd基体发生均匀溶解,表面的氧化膜被彻底去除,并且溶解后的Nd基体表面非常均匀平滑。当阳极电流密度 2 mA/cm2时,不形成粘性膜。因为没有粘性膜的“钝化—活化”作用,Nd基体发生局部溶解,在其表面形成许多点蚀坑,表面的氧化膜不能被彻底去除。在0.8：1碱性AlCl3-EMIC和[BMP]Tf2N离子液体中,Nd表面氧化膜对阳极溶解有着很大的影响,只有在一定的阳极电位(0V和1.4 V vs. Pt)下,氧化膜才会发生破坏,随后Nd发生溶解；Nd的溶解产物分别为[NdCl6]3-和[Nd(Tf2N)x](x-3)-可溶性络合离子；Nd恒电流溶解的过程中,在较低的电流密度下(分别为0.2 mA/cm2和0.1 mA/cm2),表面氧化膜在极少区域破坏,Nd发生局部溶解；在较高的电流密度下(分别为2 mA/cm2和1 mA/cm2),氧化膜完全破坏,Nd发生均匀溶解。但是由于在这两种离子液体中,Nd阳极溶解时没有粘性膜的产生,所以Nd溶解后的表面并不均匀平滑。
[Abstract]:Neodymium (Nd) is one of the most important rare earth metals. Because of its unique 4f electronic layer structure, some Nd and Nd containing alloys have special optical, electrical, magnetic and catalytic properties and are widely used in modern industry. Its main applications are permanent magnet materials, high-grade metal alloys and additives and so on. However, in practical application, surface treatment of Nd and its alloys is often needed to improve their corrosion resistance. Because of the high activity of Nd and the difficulty of surface treatment, it is an important subject in the field of surface science and technology to find a new surface treatment medium suitable for the characteristics of metal Nd and its alloys, and to study its application and mechanism. Ionic liquid is a new kind of solution, which is the third largest solvent besides water and organic solvent. It has a unique application prospect in the field of surface engineering of active metals. The anodic behavior of Nd in 1methyl-3-ethylimidazole (AlCl3-EMIC) and 1-Ding Ji -1-methylpyrrolidine bis (trifluoromethylsulfonyl) imide ([BMP] Tf2N) ionic liquids chlorided by 2:1 acidic AlCl3- has been studied in this paper. The potential windows of three kinds of ionic liquids were determined by cyclic voltammetry, the anodic dissolution of Nd in ionic liquids was studied by linear voltammetry, constant current polarization and constant potential polarization, and the dissolution valence of Nd was calculated by constant current dissolution. Finally, the surface morphology of Nd after constant current dissolution was investigated by SEM, and the surface composition of Nd was analyzed by EDS and in situ Raman. The results show that in 2:1 acidic AlCl3-EMIC, when the anode current density is greater than or equal to 5mA/cm2, a viscous film will be formed at the interface between Nd and ionic liquids. The formation of viscous film is due to the aggregation of high viscosity dissolved product Nd (鈪，
本文编号：2251496
[Abstract]:Neodymium (Nd) is one of the most important rare earth metals. Because of its unique 4f electronic layer structure, some Nd and Nd containing alloys have special optical, electrical, magnetic and catalytic properties and are widely used in modern industry. Its main applications are permanent magnet materials, high-grade metal alloys and additives and so on. However, in practical application, surface treatment of Nd and its alloys is often needed to improve their corrosion resistance. Because of the high activity of Nd and the difficulty of surface treatment, it is an important subject in the field of surface science and technology to find a new surface treatment medium suitable for the characteristics of metal Nd and its alloys, and to study its application and mechanism. Ionic liquid is a new kind of solution, which is the third largest solvent besides water and organic solvent. It has a unique application prospect in the field of surface engineering of active metals. The anodic behavior of Nd in 1methyl-3-ethylimidazole (AlCl3-EMIC) and 1-Ding Ji -1-methylpyrrolidine bis (trifluoromethylsulfonyl) imide ([BMP] Tf2N) ionic liquids chlorided by 2:1 acidic AlCl3- has been studied in this paper. The potential windows of three kinds of ionic liquids were determined by cyclic voltammetry, the anodic dissolution of Nd in ionic liquids was studied by linear voltammetry, constant current polarization and constant potential polarization, and the dissolution valence of Nd was calculated by constant current dissolution. Finally, the surface morphology of Nd after constant current dissolution was investigated by SEM, and the surface composition of Nd was analyzed by EDS and in situ Raman. The results show that in 2:1 acidic AlCl3-EMIC, when the anode current density is greater than or equal to 5mA/cm2, a viscous film will be formed at the interface between Nd and ionic liquids. The formation of viscous film is due to the aggregation of high viscosity dissolved product Nd (鈪，
本文编号：2251496
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