Experimental analysis of electrical discharge coating characteristics of magnesium alloy using response surface methodology

Electrical discharge coating (EDC) process is one of the surface modification method to deposit electrode material (WC 50% Cu 50%) on the surface of the desired material. In the present study ZE41A magnesium alloy has been coated using this method to form hard layer on the surface to resist wear and corrosion. Compaction load, current and pulse on time were selected as input responses to study the coating characteristics in the form of metal transfer rate (MTR) and surface roughness (Ra). Response surface methodology (RSM) was used to design and analysis the experiment. The most significant EDC parameters were ascertained using analysis of variance (ANOVA). From the result, it can be found that the MTR increases with increase pulse on time and decreases with high compaction load, where as MTR increases with increase current, further increase in current MTR decreases. Surface roughness increases with increases in current, pulse on time and low compaction load and conversely it diminishes with low current, pulse on time and high compaction load. Layer thickness and morphology of coated surface was analyzed using scanning electron microscope (SEM) and elements presents on the surface were confirmed using energy dispersive spectroscope (EDS).