Wire-EDM of ZTA-TiC Composites with Variable Content of Electrically Conductive Phase

Electrical Discharge Machining (EDM) enables an economical production of high performance ceramics with high hardness and toughness in complex shapes and fine structures. Recent research work identified ZTA-TiC composites as one of the most promising ED machinable materials with high strength for injection molds, which significantly reduce abrasive wear. In order to improve the surface finish and processing time of ED-machined ceramics zirconia toughened alumina composites with addition of 20-30 vol.-% titanium carbide as electrically conductive phase were developed. Processing was performed by hot pressing at 50 MPa and 1525°C. Mechanical and electrical properties were investigated. The influence of TiC volume fraction on the surface quality after wire-EDM and the maximum possible sample feed rate was analyzed. The variation of TiC content moderately influences toughness and bending strength while electrical resistivity and indentation modulus strongly depend on the volume fraction of TiC. A competitive feed rate of 2.45 mm/min for samples with a height of 13 mm was obtained. Further improvement of the surface quality can be achieved by increasing the amount of the electrically conductive phase. Additional machining steps proved feasible to decrease significantly the surface roughness and corrugation depth without inducing any defects in bulk material.