The Effect of Pulse Energy on the Defects and Microstructure of Electro-Spark-Deposited Inconel 718

Electro-spark deposition (ESD) is a technique whereby material is deposited from the ESD applicator towards a substrate via an electro-spark phenomenon. One potential use for this technique is to repair minor damages on turbine blades made of Ni-based superalloys, such as IN718. To better understand the effect of the processing parameters on the quality of the deposition, in terms of defect formation and the microstructure during the ESD process, a systematic study was carried out. In this work, IN718 deposited using ESD with different pulse energy, achieved by varying the voltage and capacitance, were systematically investigated in terms of its microstructure. It has been observed that increasing pulse energy in the ESD process promotes the formation of defects and inter-metallic phases that may be undesirable in the process of repairing or coating of components. The presence of inter-metallic particles in a certain amount and distribution is believed to increase the susceptibility for cracking of the deposited layers.