Surface modification of closed cell titanium foam through electrical discharge texturing

Abstract In this paper, the Die-Sinker Electrical Discharge Texturing (DSEDT) is utilized to machine closed cell titanium foam using pure brass tool electrode. Discharge time, current and discharge voltage were taken as input factors. By varying these input factors, discharge energy generated in between the tool and workpiece gets altered. Therefore, the influence of discharge energy on the average crater diameter, re-solidified layer thickness and chemical alteration of machined surface are analysed. The stochastic nature of DSEDT process is studied using microscopic images and energy dispersive x-ray spectroscopy profiles. Through micrographs it is perceived, increase in the discharge energy from 5.12 J to 10.13 J, leads to an increase in average crater diameter from 29.26 to 66.29 μm respectively. It is observed that combined effect of crater overlap phenomena and re-solidification of material seals the cells in a foam material. A minimum re-solidified layer thickness of 44.29 μm is achieved. The machined surface of closed cell titanium foam shows significant rise in carbon, copper and zinc elements owing to the disintegration of the dielectric liquid and tool electrode during spark erosion. The study on DSEDT of closed cell titanium foam revealed the possibility to create surfaces with uniform crater diameter and establish titanium carbide on the machined surface.