Surface Modification of AISI 1020 Mild Steel by Electrical Discharge Coating with Tungsten and Copper Mixed Powder Green Compact Electrodes

Electro discharge machining (EDM) is a non- conventional machining process, which is widely used for machining of very hard materials used for engineering purposes. In Electrical Discharge Coating (EDC) process tool electrode which is manufactured by powder metallurgy (P/M) technique, connected to anode and work-piece (on which coating is to be done) is selected as cathode in electro discharge machine (polarity opposite to the electrical discharge machining). In presence of dielectric, tool electrode is worn out during EDM and the material removed from the surface of electrode deposited over the work-piece surface. This project work describes an advanced method of surface modification by Electrical Discharge Coating (EDC). In this work Tungsten carbide and Copper (WC- Cu) composite coating deposited on AISI 1020 mild steel substrate. Tungsten (W) and Copper (Cu) powder in different weight percentages has been used for preparation of tool electrode by P/M process. Effect of compact pressure, proportions of powder of materials (during tool preparation) and peak current (during EDC) on deposition rate of the coating and tool wear rate has been investigated. By using X-Ray Diffraction (XRD) technique different phases formed in the deposited layer during the process has been identified. Scanning Electron Microscopy (SEM) has been done to reveal the microstructure of the coated surface. Vickers‟ Micro hardness testing has been performed on the coating to measure the hardness values of coated surface.