Effect of direct current and pulse plating on the EDM performance of copper-zirconium diboride composites

Direct current and pulse plating of copper-zirconium diboride (ZrB₂) composites were studied and the effects of current density (DC) and pulse duty cycle (PC) on the EDM performance of the composites were investigated. With increasing current density, the effect of grain refinement on the electro-discharge machining (EDM) performance of the composites compensates that of the decrease of ZrB₂ content in the composites, which improves the spark-resistance of the material. Under the same average current density and other experiment conditions, a lower duty cycle yields better EDM performance probably because more ZrB₂ particles are incorporated in the composites in this condition. However, at a still lower duty cycle (10%), the particle agglomeration and the microcracks of the copper matrix occur, which considerably deteriorate the spark-resistance of the composites.