Experimental investigation into the effects of electric discharge surface modification process parameters on the biocompatibility of Ti6Al4V

Titanium alloys especially Ti6Al4V is extensively used in the fabrication of biomedical implant due to its similar mechanical properties as of bone, bio compatibility, high strength to weight ratio, better resistance to the body fluid and corrosion resistance etc. However, in order to further improve the osteointegration, anti-bacterial, anti-corrosion, and anti-wear properties, various surface modification or coating methods are often essential. Moreover, the biological behavior of surrounding cells on the implants depends on its various surface properties like surface roughness and wettability, etc. Therefore, in this paper a comprehensive experimental investigation is planned to investigate the influence of electric discharge-based surface modification process parameters on the bio-compatibility of Ti–6Al–4V. The important process parameters such as current and pulse ON time was varied at three different levels with double deionized water as the dielectric fluid to generate different functional surfaces. The areal surface roughness, wettability, surface elemental composition and morphology, etc. were analyzed in detail using scanning electron microscopy (SEM), X-Ray Diffractometry (XRD), Energy Dispersive x-ray spectroscopy (EDS). It is observed that the surface roughness values varied between 2.9 µm to 5.4 µm with respect to the variation in the pulse ON time and current. Similarly, the contact angle also varied between the hydrophilic to hydrophobic with respect to the number of days from the development of the surfaces. In addition, it is observed that a good amount of oxygen got deposited on the surface and formed various bio active titanium oxides which enhances the cell viability, cell adhesion and proliferation. The cytocompatibility tests with L929 fibroblast cells as per the ISO 10993-5, showed a maximum of cell viability up to 84.69% with 70.6633% of cell survival.