Electrical Discharged Machining Using Electrodes Of ZrB₂ Infiltrated With Copper

Abstract

The objective of this research is to evaluate the performance of ZrB₂ infiltrated with copper as an alternative material system to the standard electrodes of copper and graphite used in electrical discharged machining (EDM). ZrB₂ powder particles are coated with a polymer binder and then cold pressed in a square die. The cold pressed electrodes are then annealed in a furnace to burn off the polymer binder coating and to sinter the ZrB₂ particles together. The 50-60% dense part is then infiltrated with a doped copper using capillary action, producing a 100% dense electrode. The electrode is then milled to produce the final 3/8" x .3/8" cross sectional square electrode. The anode, ZrB₂/Cu is tested at a constant current and constant off-time with different on-times. The steel workpiece is the cathode. The results clearly show that ZrB₂/Cu displays a higher workpiece removal rate, lower tool removal rates, and a lower wear ratio. Further research on infiltrating ZrB₂ with pure copper and finding the on-time for maximum removal rates will define even more optimal performance characteristics. Therefore, one may conclude that the production of ZrB₂/Cu electrodes using selective laser sintering will produce superior electrodes relative to the industry standard electrodes of graphite and copper.