Fabrication of Fe-based metal glass microelectrodes by a vertical liquid membrane electrochemical etching method

The excellent physical and chemical properties of metallic glasses and the absence of crystal defects make them ideal materials for the preparation of microelectrodes. A vertical liquid membrane electrochemical etching method is proposed here for the fabrication of microelectrodes from the Fe-based metallic glass Fe_77.5B₁₅Si_7.5. With this method, insoluble electrolysis products are kept away from the processing area, and the nonuniformity of the diffusion layer that occurs in traditional transverse liquid membrane electrochemical etching is reduced. Simulations of the potential distribution and the current density distribution are carried out in COMSOL software, and the simulation results are verified by experiments. The passivation characteristics of the Fe_77.5B₁₅Si_7.5 metallic glass in H₂SO₄ and H₃PO₄ electrolytes are studied. The effects of processing voltage on electrode morphology and surface quality are studied experimentally. Micropins with good tip size can be prepared in the active dissolution stage in 0.1M H₂SO₄ solution, and high-aspect-ratio cylindrical microtool electrodes with high surface quality can be fabricated in the transpassivation stage in 80% H₃PO₄ electrolyte with high machining stability.