Dry-electropolishing (DEP) combines an electrochemical process with soft-mechanical abrasion by using porous ion-exchange particles (also known as dry-electrolyte). In recent years, it has been satisfactorily implemented for reducing surfaces defects, decreasing roughness, and obtaining smooth surface finish in several metallic and ceramic-metal composites. However, it requires a preliminary adjustment of DEP parameters in order to increase the polishing efficiency and avoid pitting or general corrosion issues. Moreover, there is a lack of information concerning the precise material removal mechanisms, this being particularly true for multiphase materials. In that sense, the main objectives of this study are to optimize the electrical parameters as well as to understand the main microstructural and chemical changes behind the DEP process on WC-Co. It is done by implementing several advanced characterization techniques: scanning electron microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The results demonstrate that optimal electrical parameters in terms of planarity between constitutive phases, average roughness reduction and leaching-free microstructure can be achieved when utilizing a pulse/pulse reverse waveform in comparison to direct current or pulsed current. Optimization using a matrix of electrical parameters is proven to be a useful tool to focus on the results, these being when voltage and time of negative pulse applied higher values than the positive ones. Additionally, it is shown that the chemical compounds generated on the WC-Co surface are meanly Co3O4, Co(OH)2 and WO3. Material removal combines electrochemical process and also soft-mechanical actions, where particles contact oxides generated on the treated surface. The removed material mainly consists of W oxide, as Co passivates and has a low oxidation rate combined with its low content. To sum up, the corresponding analysis allows to get a deeper understanding of DEP along the roughness removal process as well as to give guidelines for optimizing its operative parameters for its application in multiphase ceramic/metal materials.

中文翻译：

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优化和了解 WC-Co 硬质合金材料的干法电解抛光工艺


干电解抛光 （DEP） 通过使用多孔离子交换颗粒（也称为干电解质）将电化学过程与软机械磨损相结合。近年来，它在减少表面缺陷、降低粗糙度和在几种金属和陶瓷-金属复合材料中获得光滑的表面光洁度方面得到了令人满意的实施。但是，它需要对 DEP 参数进行初步调整，以提高抛光效率并避免点蚀或一般腐蚀问题。此外，缺乏有关精确材料去除机制的信息，对于多相材料尤其如此。从这个意义上说，本研究的主要目标是优化电参数以及了解 WC-Co 上 DEP 工艺背后的主要微观结构和化学变化。它是通过实施几种先进的表征技术来完成的：扫描电子显微镜、X 射线光电子能谱和能量色散 X 射线光谱。结果表明，与直流电或脉冲电流相比，使用脉冲/脉冲反向波形时，可以实现本构相之间的平面度、平均粗糙度降低和无浸出微观结构方面的最佳电学参数。使用电气参数矩阵进行优化被证明是关注结果的有用工具，这些结果是当负脉冲的电压和时间应用的值高于正脉冲的值时。此外，结果表明，在 WC-Co 表面生成的化合物平均为 Co3O4、Co（OH）2 和 WO3。材料去除结合了电化学过程和软机械作用，其中颗粒接触处理过的表面产生的氧化物。 去除的材料主要由 W 氧化物组成，因为 Co 钝化，具有低氧化速率和低含量。总而言之，相应的分析可以更深入地了解粗糙度去除过程中的 DEP，并为优化其操作参数以使其在多相陶瓷/金属材料中的应用提供指导。