A Comparative Study on Machining Capabilities of Wet and Dry Nano-scale Electro-machining

Presently, the nano scale electro-machining (nano-EM) process has been demonstrated in both the liquid and air dielectric mediums, which are known as wet and dry nano-EM respectively. In the current study, two important aspects of the nano-EM have been investigated: the minimum possible feature dimension and mass fabrication capability of nano-EM. Firstly, the investigation has been done on the capability of machining graphene at atomic scale with focus on obtaining smallest possible nano-feature using the wet nano-EM. Secondly, the ability of the nano-EM process for the fabrication of arrays of nano-holes has been investigated using dry nano-EM. It was found that nano-features of 3 to 4 nm could be machined in graphene surfaces revealing the atomic arrangement of carbon using the wet nano-EM process. The dry nano-EM was found to be capable of fabricating arrays of nano-features making it more suitable for mass fabrication. The field induced evaporation of materials from the tool during dry nano-EM retained the quality of tool electrode, thus making the process capable of fabricating more than 100 nano features in a single step. It was found that the material removal mechanism influenced the machining capability of the process. The mechanism of material removal in the wet nano-EM was associated with the dielectric breakdown of liquid n-decane generating intense heat for ionization, evaporation, and melting of materials. On the other hand, the material removal mechanism of dry nano-EM was associated with the breakdown of air, which generated intense heat at the gap between the nano-EM tool and the workpiece causing localized ionization and evaporation.