A Framework for Surface Modification by Electrical Discharge Coating using Variable Density Electrodes

Abstract

Surface modification is the process of altering physical or chemical characteristics of the work-piece surface. In this paper, various surface modification techniques have been discussed. One of the most appropriate surface modification technique is electrical discharge coating (EDC), in which the hard material is made to deposit onto the work-piece in a state of reverse polarity condition. Different mechanisms of carrying out EDC are presented. Deliberate material transfer takes place by using electrodes or by dispersant of metal powders into the di-electric. A detailed review of the literature on the theme of surface modification through the EDC has been conducted. In last, a framework for conducting surface modification by EDC employing using density electrodes of same material is presented.

Electric discharge coating process: a critical review with potential application

“…Muralidharan B et al [35] experimentally investigate electric discharge deposition using a solid electrode with magnetic field, and the results show deposit increased by magnetic field effect. Khan MY et al [36] explain about EDC process and gives an overview on Coating with different types of electrodes, especially Coating with solid electrode. EDC with solid electrodes can develop coating layer up to 20 μm process.…”

Numerical Simulation of the Coating Process of some Metals by Electrical Discharge Deposition

“…At longer pulse time, the ionic current is dominant within the plasma channel, so the power to the cathode (Pc) is increased -see relation (1). So, when using commanded pulse with long duration (like at EDM), the cathode could be the tool-electrode.…”

“…The following variants of EDD or EDC (electrical discharge coating) are existing -Fig. 1: (1) the transfer of material to be deposited from tool-electrode -that can be a usual metallic material (1.a) or another one formed through powder metallurgy (1.b) or even 3D printing (1.c) -by sparks generated between the tool and the workpiece surface to be coated, inside the working gap -the space between the tool and the workpiece; this can be filled by a dielectric liquid (1.d) or by air (1.e) [1,2,14]; (2) material to be deposited is provided by powder suspension (2.a) from the dielectric liquid supplied in the working gap by discharges produced by pulse voltage applied between the tool and the workpiece [3]. When a dielectric liquid is used inside the working gap, instead of air, the deposition of the metals from the tool-electrode can be combined with the carbon from the decomposition of dielectric liquid, forming metallic carbides (2.b) [2].…”

Electrical Discharge Coating a Potential Surface Engineering Technique: A State of the Art

“…The average current is the average of the amperage in the spark gap measured over the pulse on time in a cycle [111]. During the EDC coating, the peak current assists in initiating the electrical spark to reach up to the spark temperature that is required to deposit the tool material on the parent material [112]. Thus, optimum value of current is needed to transfer the maximum material to achieve a denser and more uniform coating [113].…”