Achieving nano-patterned features by micro-EDM process using vertically aligned ZnO nanorods grown on microprobe tip: A scaling approach

Abstract

Fabricating the nanopatterned features through a cost-effective nanomachining technique is one of the great challenges in NEMS industries. The micro-electrical-discharge machining process is one of the promising machining technologies which is capable to write the micro-scale features on any electrically conductive materials. However, its potential has not been tested yet for replicating the nanoscale features through the scaling approach. Hence, this article addresses a scaling approach for fabricating the nanopatterned features on super finished titanium alloy (Ti-6Al-4 V) using vertically aligned ZnO nanorods grown on the apex of the microtip. For achieving this, first of all, cylindrical micro-tools of diameter (ø) 90–95 μm (tungsten) were fabricated through a micro-electrochemical turning process under KOH (2.5 M) electrolyte medium. On the apex of the micro tools, the ZnO nanorods were grown by the low-temperature hydrothermal process by dipping the apex of the tip in seed and growth solution followed by essential heat treatment at 90 °C. It was found that the grown nanorods were well defined in shape and size and further utilized as nanotools during short-duration discharge (5 ms) μ-EDM experiments. It was expected that by downsizing the tooltip, the discharge energy per unit pulse may be reduced due to the localization effect. Moreover, it is well-known fact that the discharge happens only in the nearest established gap in the μ-EDM process. The experimental results of this study confirmed the same. The FESEM micrographs were utilized for the morphological characterization of formed nanopatterned cavities, microtools, and nanorods while the chemical characterization of the same is carried out by EDX spectroscopy. Additionally, the stability of the machining process was tested first for multiple discharge energy pulses then after a short duration discharge energy pulse has been characterized by voltage-current (V-I) waveforms during nanocavity fabrication. Finally, the supporting results of this experimental investigation show the feasibility of the approach towards nano-EDM with extensive potentials/applications in micro/nanofabrication devices.