Surface Modification of Al-7075 Alloy by SiC-Cu Ceramic Electrode in Electrical Discharge Coating

The present study aims to enhance and evaluate Electrical Discharge Coating (EDC) on Al-7075 alloy using SiC-Cu ceramic electrode. The study analyses the impact of input parameters such as current, composition and compaction load on EDC responses, including Material Deposition Rate (MDR), Tool Wear Rate (TWR) and Surface Roughness (SR). Trial tests were performed using Taguchi's L9 experimental design, and thereafter, Grey Relational Analysis (GRA) and technique for order preference by similarity to an ideal solution (TOPSIS) were implemented to optimize all the responses. The experiments were optimized to achieve a higher MDR, lower TWR and lower SR. Analysis of variance was also employed to statistically investigate the experimental data and determine the contribution of each parameter to achieve better results. Optimum condition was achieved with a compaction load of 5 ton, current 6 A and composition 50:50, using both the GRA and TOPSIS methods. At the optimum condition, there was an improvement in GRA from 0.5603 to 0.7778, while TOPSIS showed an improvement from 0.2418 to 0.7659. Further, the morphology of the coated surface was investigated using scanning electron microscopy images and X-ray diffraction analyses, which confirmed the migration of SiC-Cu from the tool materials.