Impact of wire-EDM on dry sliding friction and wear of WC-based and ZrO2-based composites

Linearly reciprocating sliding wear experiments on WC-Co and WC-Ni cemented carbides and ZrO2-WC, ZrO2–TiCN and ZrO2–TiN composites with different surface finishes corresponding to sequential wire-EDM or grinding/polishing have been performed using an ASTM G133 system with WC-6 wt%Co cemented carbide as counter body. The WC-based alloys contained 6 up to 12 wt% of binder, whereas the amount of secondary phase for the ZrO2-based composites was 40 vol.% pin-on-plate testing was carried out in unlubricated circumstances at constant oscillating frequency with fixed displacement amplitude and normal contact loads ranging between 15 and 35 N. 3D topography mapping and volumetric quantification of the wear tracks was obtained by surface profilometry. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were employed to observe morphological and chemical features of worn surfaces and wear debris. The identified wear mechanisms are discussed. The highest wear resistance was encountered with the WC-Ni alloy, whereas the ZrO2–TiN composite displayed the lowest wear resistance. Wire-EDM surfaces displayed higher friction and wear compared to their ground/polished equivalents, especially during running-in. The inferior wear resistance of wire-EDM’ed samples could be correlated to 3-point bending tests, revealing a considerable decrease in flexural strength compared to ground samples.