Surface morphology and drilled hole accuracy of conductive ceramic composites Si3N4–TiN and MoSi2–SiC on EDMed surfaces

Abstract

Electro-discharge machining (EDM) was employed to cut conductive ceramic composites consisting of Silicon Nitride-Titanium Nitride (Si3N4–TiN) and intermetallic ceramic composite (MoSi2–SiC), with the geometrical properties of the machined hole and the measurement of performance metrics of essential concern in the EDM process being recorded. Machining characteristics including current, spark on time, spark off time, and dielectric pressure are compared for both conductive ceramic composites. For multiple responses to geometrical errors such circularity, cylindricity and perpendicularity, as well as to performance metrics like metal removal rate (MRR), electrode wear ratio (EWR), machining time and workpiece and electrode surface integrity, spark gap time is preferable. The experimental runs to determine the optimal parameters of Si3N4–TiN and MoSi2–SiC ceramic composite are carried out using Taguchi's L9 OA based on the design of experiments (DOE). SEM with EDAX analysis of the machined surface of both composites allows for in-depth research into the machining process and a comparison of the removal mechanism and surface topography. The surface textures of 9 different holes and electrodes for ceramic composites are analysed by comparing the machined surface of the best hole with the best electrode to the machined surface of the worst hole with the worst electrode. As a consequence, the EDM process seems to be a promising method for manufacturing excellent surfaces in an electrically conductive Si3N4–TiN and MoSi2–SiC composite under the slow process parameters condition of conductive ceramic composites. This was demonstrated by the comparative analysis and establishing that was previously discussed.