ELECTRICAL DISCHARGE COATING: AN ALTERNATE FOR SURFACE TREATMENT

Electrical Discharge Coating(EDC)/ surface modification/ alloying as a cheap alternate by reversing the polarity of a normal non-conventional Electrical Discharge Machine (EDM) used for fabricating the cavities on hard metals surface that can’t be machined by convention machining like lathe, milling, etc. During machining the entire work material immersed in the die electrical fluid underwent rapid heating and cooling results in metallurgical transformations and white/carbon layer formation over surface due to absorption of pyrolysis carbon form the dielectric. The addition of alloying elements nickel and copper within the white layer shows excellence towards mechanical and metallurgical properties. EDC improves the hardness of the duplex steel to 780HV by EDM oil inclusion of alloying element shows 1300HV. The specific wear rate of substrate material is reduced from1.252x10^-5mm³/Nm to 0.192x10^-5mm³/Nm and its varies to 0.545 x10^-5mm³/Nm for oil. In normal EDM/ EDC machining the layers are categorised in to white layer, Heat Affected Zone(HAZ) and annealed layer are controlled by alloying powders further it reduces the brittleness and porosity. The metallurgical modification of those layers are identified through Scanning Electron Microscope (SEM), Element mapping through Electron Dispersive Spectroscopy(EDS), phase transformation through X-ray Diffraction(XRD) and wear though Pin on Disc.