Wire electrochemical micromachining of metallic glass using a carbon nanotube fiber electrode

Metallic glasses are promising materials for realizing high-performance micro devices in micro-electromechanical systems (MEMS) owing to their excellent functional and structural characteristics. A significant limitation to their application is the challenge of shaping them on a microscale. A technique of wire electrochemical micromachining (WECMM) with a carbon nanotube fiber (CNF) as tool electrode is proposed for microstructure fabrication of metallic glass. WECMM is a type of electrochemical micromachining (ECMM) that is increasingly recognized as a flexible and effective technology to fabricate complex-shaped micro components. Taking the example of a Ni-based metallic glass, Ni72Cr19Si7B2, the polarization and fabrication characteristics in dilute acid electrolytes are investigated. As the machining gap is very small in WECMM, efficient mass transport is extremely important to improve the machining efficiency, stability, and quality. The efficiency of enhancing mass transport using a CNF electrode in this work is shown by flow-field simulation and hydrophilicity analysis, as well as experimental investigation. The maximum feed rate can be doubled and the homogeneity of machined slits improved more than five times compared with the results obtained using a smooth tungsten wire. Finally, complex microstructures based on metallic glass are fabricated by WECMM using a CNF electrode successfully.