In this study, an endeavour have been made to depositing the electrode materials over the surface of the magnesium alloy using electrical discharge machining (EDM) with WC-Cu powder compacted sintered electrode. Various process parameters such as compaction load, discharge current and pulse on time are selected to carry out the experiment in order to attain the maximum material migration rate (MMR) or deposition rate and microhardness (MH). It was concluded that the MMR and MH increased with increase in discharge current and pulse on time at low compacted electrode but it is decreased at lower discharge current and pulse on time. Highest MMR and MH were attained successfully at partial sintered low compaction load electrode. Microstructure evaluation has been carried out on deposited surface using scanning electron microscopy (SEM) and presence of electrode element in the deposited surface was confirmed by energy dispersive spectroscopy (EDS). Defects mechanism such as globules and craters are formed during EDC with high current and pulse on time respectively, which diminishes the surface roughness. It was observed that the compaction load is the influence parameter on the MMR and MH.

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.

Electrical discharge coating is a material transfer process of EDM used for fabricating composite coating on the workpiece surface. It is applied in the several applications such as surface texturing, die and mould making industries in order to increase the wear and corrosion resistance. In this investigation, ZE41A magnesium alloy is coated with tungsten carbide- Copper (WC-Cu) powder metallurgy electrode. Electrodes are prepared under three different load conditions (150, 175 and 200 MPa). Effects of process parameters on microstructure of the coated surfaces are studied. EDC experiment is carried out by varying the process parameters viz. compaction load (CL), current (I) and pulse on time (Ton). Response characteristics considered in this study are material migration rate (MMR), layer thickness (LT) and micro hardness (MH). MMR, LT and MH increases with increase in current and pulse on time at low compaction loaded electrode. Conversely, it is decreased with low current and pulse on time at high compaction loaded. Average micro hardness of the deposited surface was 125 HV and average layer thickness was 91.6 μ m. Different surface defects were identified in the deposited surface such as cracks, craters and globules. Bigger craters were observed at surface deposited with higher current (4 A) that reduced the hardness of the surface.