Surface modification of a magnesium alloy by electrical discharge coating with a powder metallurgy electrode

Abstract

Abstract The present paper elucidates an experimental study on the surface modification of a ZE41 A magnesium alloy by electrical discharge coating (EDC) process with a tungsten carbide-copper (WC-Cu) powder metallurgy (PM) electrode. Investigated EDC parameters were compaction load, current and pulse on time. Measurement of coating characteristics such as material transfer rate (MTR) and surface roughness (Ra) were undertaken on the coated workpiece. As the design of experiment, response surface methodology was applied and analysis of variance (ANOVA) test was completed to study the influence of process parameters. Mathematical models were developed for coating characteristics to optimize the parameters. In this study, the reliability of the regression model is considered satisfactory with a value larger than 99 %. It was found from the study that the current plays a vital role in increasing the material transfer rate and minimizing the surface roughness of the coated surface followed by compaction load and pulse on time. Various studies such as scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were carried out to determine the characteristics of the coated layer. These analyses confirmed the presence of the electrode materials in the coated surface.