Effect of zirconium diboride addition on the properties of silicon carbide composites

SiC and its composites have large potential in the aerospace sector due to their inherent advantages. However, the beneficial properties of high hardness and high strength of SiC cause problems in fabricating these composites by machining. Electro discharge machining (EDM) is found to be reliable technique to machine such hard materials and demands the work material to be conductive. Thus the present work focuses on synthesizing SiC composite with 10, 20, 30 vol% zirconium diboride (ZrB2) as reinforcement to study the physical and mechanical properties and its machinability by EDM. SiC and its composites were vacuum hot pressed at 1900 °C to near theoretical densities. It was observed that with the addition of ZrB2, hardness of the composite increased while the flexural strength decreased and the electrical resistivity decreased with increase of ZrB2 content. Feasibility studies of machining the composites with EDM were carried out and the experiments showed that SiC–30 vol% ZrB2 composite alone could be machined. This revealed that this composite possessed adequate conductivity for carrying out EDM.