Effect of shapes and compositions of spark plasma sintered ZrB₂-C composites on performance as EDM tools

A systematic investigation on the fabrication of Zirconium diboride-Graphite composites for application as Electrical Discharge Machining tools has been carried out. Various percentage of graphite powder (in weight) is added to Zirconium diboride powder before Spark Plasma Sintering and the compositions, as well as the shapes of these composites, are varied to study its effect on the Tool wear rate and Material removal rate. The electro-discharge machining performances of these composite tools are compared with copper electrodes and best material removal rate to tool wear rate ratio is achieved for the Zirconium diboride-5wt% Graphite composite tools while electrodischarge machining of AISI steel. Amongst all the shapes, the circular tools have the highest material removal rate to tool wear rate ratio. The improved performance of the Zirconium diboride-5wt% Graphite composite tools is due to better densifications than the other composites.