The electropolishing (EP) mechanism of niobium (Nb) in relatively eco-friendly deep eutectic solvents (DES) instead of the widely used HF-based electrolyte was studied by anodic polarization (AP) tests and electrochemical impedance spectroscopy (EIS) using a rotating disk electrode (RDE) of Nb. The AP test results reveal that the EP progress of Nb is under a mixed control of ionic transport and charge transfer. EIS results suggest the niobium EP process is consistent with the compact salt film mechanism in this electrolyte. The influence of applied potential and electrolyte temperature on the EP rate, surface roughness, and surface glossiness of Nb was also investigated. The crystal structure, chemical composition and surface morphology of Nb samples before and after EP were analyzed by XRD, XPS, and SEM. The grain sizes and preferential orientation of Nb before and after EP are changed. XPS depth profiling has been produced by sputtering with Ar⁺ ions which revealed that with the increase of Ar⁺ sputtering depth, the content of low-valence Nb⁰, NbO increases, high-valence Nb₂O₅ decreases, and middle-valence NbO₂ increases first and then decreases. It indicates the existence of the Nb → Nb²⁺→Nb⁴⁺→Nb⁵⁺ transition process. An even and mirror-like Nb surface can be obtained after EP from DES.

通过阳极极化（AP）测试和电化学阻抗谱（EIS）的旋转研究了在相对生态友好的深共熔溶剂（DES）而不是广泛使用的基于HF的电解液中铌（Nb）的电抛光（EP）机制Nb的圆盘电极（RDE）。AP测试结果表明，Nb的EP进展受离子迁移和电荷转移的混合控制。EIS结果表明，铌EP工艺与该电解质中的致密盐膜机理一致。还研究了施加电势和电解质温度对Nb的EP速率，表面粗糙度和表面光泽度的影响。用XRD，XPS和SEM分析了EP前后Nb样品的晶体结构，化学成分和表面形貌。改变EP前后的Nb的晶粒尺寸和优先取向。XPS深度轮廓分析是通过用Ar溅射进行的⁺离子表明，随着Ar ⁺溅射深度的增加，低价Nb ⁰，NbO的含量增加，高价Nb ₂ O ₅降低，而中价NbO ₂先升高然后降低。这表明存在Nb→Nb 2 ⁺ →Nb ⁴⁺ →Nb ⁵⁺过渡过程。通过DES进行EP后，可以获得均匀的镜面Nb表面。