Enhancing tribological performance of β-titanium alloy using electrical discharge process

Abstract

In this study, medical-grade β-titanium (Ti–35Nb–7Ta–5Zr) alloy was treated using the electrical discharge machining process. Biofavorable substances, such as multiwalled carbon (C) nanotubes and μ-hydroxyapatite powder, were selected for possible deposition during the production of spark between electrodes. The L18 array was used to conduct the experiments considering polarities, peak current, pulse on time, pulse off time, dielectric medium and tool electrode material as machining variables. The treated surfaces were evaluated in terms of change in surface microhardness, recast layer morphology and wear behavior. The outcome revealed that the alloy treated at high spark energy using a tungsten (W) tool electrode incorporating multiwalled carbon nanotubes in the dielectric medium favored the synthesis of a high-quality wear-resistant substrate. The presence of titanium carbide (TiC), niobium carbide (NbC) and tungsten carbide (WC) phases detected from X-ray diffraction examination confirmed that the microhardness of the recast layer, as well as wear resistance of the substrate, was significantly affected by multiwalled carbon nanotube deposition.