Parametric study on surface modification of Al-7075 alloy using electric discharge coating

Abstract

This work investigates the surface modification of Al-7075 alloy using a copper-multi-walled carbon nanotube powder metallurgical green compact tool in the electric discharge coating process. The effect of input parameters such as compact load, peak current ( Ip), and pulse on-time ( Ton) on material deposition rate and surface roughness ( Ra) has been investigated. The process parameters are optimised using the teaching learning-based optimisation algorithm. Maximum material deposition rate of 0.62 mg/min with minimum Ra of 3.00 µm has been achieved at compact load of 6 tons, Ip of 2.5 A, and Ton of 1000 µs. The field emission scanning electron microscopy images show smooth surface generation at low Ip and compact load settings. Characterisation using different techniques confirms the presence of tool materials on the modified surface. The microhardness test of the modified surface exhibits a higher hardness value of 2.70 times than that of the substrate material.