Fabrication of micro holes in Yttria-stabilized zirconia (Y-SZ) by hybrid process of electrochemical discharge machining (ECDM)

Abstract

In the present work, the electrochemical discharge machining (ECDM) process with an integrated approach of electrolyte flow and pressurized feeding is demonstrated to produce micro-holes in Yttria-stabilized zirconia (Y-SZ). The mechanism of material removal reveals that the material is primarily removed due to the thermal spalling phenomenon over the melting and evaporation. Unlike the other glass based ceramic materials, the contribution of chemical etching phenomenon is found to be almost negligible in removing the material from Yttria-stabilized zirconia work substrate. The incorporation of electrolyte flow in the ECDM process increases the machining efficiency by improving hole depth by 42% and reducing diameter by 33% for the same processing durations. The improved frequency of electrochemical discharges (ECD’s) due to the supply of electrolyte is responsible for removing the material in controlled manner without causing any fracture at the hole edges. Moreover, the supply of electrolyte reduces the tool wear, which results in consistent machining conditions for longer machining durations. The maximum penetration speed obtained in this investigation was 126 μm/min.