Formation and Optimization of Electrical Discharge Coatings Using Conventional Electrodes

Abstract

An emerging topic is electrical discharge (ED) coating with its application on complex shapes and cavities to repair components or act as functional coatings. Because it is a variant process of an electric discharge machine (EDM) with the ability to coat on electrically conductive substrates, there is a possibility that next-generation electrical discharge machining components may exploit the attachment phenomenon to enhance recast layer properties. Previously, researchers have obtained ED coating by mixing the powder in a dielectric medium and/or by using powder metallurgy electrodes. In this work, primarily, an insight in the formation of ED coating on-die sinks electrical discharge machine, using conventional electrode materials viz., bronze on titanium alloy (Ti-6Al-4V) is made. The bronze electrode on the titanium substrate obtained a crack-free copper coating of ~20 microns thickness. In order to perform the experiments, three combinations were made using five parameters: current (Amps), ton (µs), Toff (µs), duty cycle (%), and flushing pressure as constant (bar). After obtaining the coating, a combination of input parameters was selected by optimizing the output performance parameters, viz., the electrical discharge deposition rate, coating thickness, micro-cracks, and elemental coating composition. Secondarily, different optimization techniques viz., grey relational analysis, the technique for order of preferences by similarity to ideal solution, −nD angle method and information divergence method were implemented to find out the suitable combination of parameters where the latter two methods were introduced for the first time in this area of EDM optimization. A study was conducted to check whether the latter two methods are optimization techniques or multi-criteria decision-making techniques. The optimization of existing reactor types and the development of new reactors in wastewater treatment through EDC, by which energy could be saved by replacing the conventional techniques.