Electrical discharge machining of ZrO2/TiN particulate composite

An experimental study was conducted into the electrical discharge machining (EDM) characteristics of a zirconia based composite with 30 vol.-% of a ti tanium nitride dispersoid added to provide a conductive network. The materi al removal rates and tool wear were assessed under normal sparking and indu ced arcing conditions and the influences of the main machining parameters a re discussed for both conditions. The apparent cost effectiveness of materi al removal by arcing discharges was highlighted by assessment of the specif ic volumetric power consumption (SVPC). Subsequent microscopic analysis of the arced surface and the debris collected during machining under induced a rcing indicated the major mechanism of material removal to be a combination of three distinct fracture events: subsurface lateral cracking caused by r apid heating, vertical cracking caused by the tetragonal/monoclinic phase t ransformation in the zirconia matrix, and thermal shock induced fracture on rapid cooling. BCT/359. (C) 2000 IoM Communications Ltd.