Electrically conductive ZTA-TiC ceramics: Influence of TiC particle size on material properties and electrical discharge machining

This study focuses on the influence of TiC particle sizes on material properties and EDM machinability of ZTA-TiC ceramics with 24 vol.% TiC, 17 vol.% ZrO2 and 59 vol.% Al2O3. Fracture toughness, bending strength and electrical conductivity were analyzed for samples produced from TiC powders with particle sizes varying from 0.43 μm to 2.54 μm. Surface integrity of wire cut samples and feed rate during machining were investigated. It was shown that reducing the size of electrical conductive grains strongly increases the electrical conductivity and slightly decreases mechanical properties. Therefore also the machining characteristics are influenced by TiC grain size. The feed rate increases with decreasing particle size to a maximum at d50 = 1-1.3 μm. Reduction of TiC particle size also leads to significantly decreasing surface roughness after the main cut. Additionally the necessary number of trimming steps to achieve a distinct surface roughness is also minimized for low particle sizes.