Investigating wettability and corrosion resistance of the titanium alloy surface engineered by the WEDM process

Abstract

Ti-6Al-4V or the grade 5 titanium alloy, is widely used as a biomedical implant material because of its high specific strength and corrosion resistance. The formation of oxide layer over the Ti-6Al-4V alloy produced by electrical discharge machining (EDM) process was reported to act as a corrosion barrier and promote biocompatibility. In this study, surface engineering was conducted by machining micro-channels and micro-pillars over Ti-6Al-4V surface using wire-EDM (WEDM) process to investigate surface topography, corrosion resistance and wettability for improved biocompatibility. Four different samples were produced using varied micro features and varied surface topography generated by WEDM. Two of the samples were prepared by multi-pass surface finishing before fabricating micro-patterns on the surface, whereas the other two samples containing micro-patterns were first machined by single pass WEDM process. The corrosion testing was carried out on fabricated samples in simulated body fluid. Surface wettability of the engineered Ti-6Al-4V samples were carried out by measuring water contact angles of the surfaces. Surfaces with micro-channels and micro-pillars with multi-pass surface finishing provided better results in terms of corrosion resistance compared to the samples prepared by conventional WEDM process. The machined surface with micro-channels that underwent multi-pass finishing exhibited the highest corrosion resistance as well as the highest water contact angle among the four samples.