Surface modification of Hastelloy processed by the Cu mixed electric discharge alloying technique

Abstract

An attempt was made in this study to coat Hastelloy with copper carbide utilizing an electric discharge alloying process. Experiments were carried out in such a way that materials were initially removed from the surface, but after a prescribed time in the absence of flushing, it was coated on the surface. Experiments were conducted by varying copper powder concentration, current, pulse on time, and gap distance and experimental runs were designed using the Taguchi mixed orthogonal array. Pure dielectric medium materials were removed from the surface, at 5 g l⁻¹ PMEDM material removal followed by deposition occurred, beyond 10 g l⁻¹ PMEDM condition, only material deposition was observed. Surface topography revealed that the cracks formed on the coated surface with an increase in Cu concentration get intensified and penetrated the base material. The hardness and wear resistance of coated samples are enhanced owing to the presence of harder carbide particles and mechanically mixed layer formation. The mode of wear was adhesive and abrasive for the uncoated and coated samples.