In vitro corrosion and bio-tribocorrosion performance of electron beam powder bed fusion Ti6Al4V specimens with lapping and superfinishing treatments

Lapping and superfinishing treatments were adopted to enhance the corrosion performance of electron beam powder bed fusion (EB-PBF)–Ti6Al4V alloys, and the results were compared with those of the wrought counterparts. The effect of the lapping and superfinishing on the electrochemical behaviour of the samples was scrutinized in a phosphate-buffered saline (PBS) + H2O2 solution with and without bovine serum albumin (BSA) employing potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Profilometer data revealed an impressive 80% and 95% reduction in surface roughness for lapping and superfinishing, respectively, compared to the grinding process. Following a wettability test, smoother surfaces exhibited increased hydrophilicity, with contact angles for the wrought samples ranging from 73.13° (lapped) to 87.59° (grinded) and for the EB-PBF–Ti6Al4V samples from 72.87° (superfinished) to 89.15° (grinded). The electrochemical findings indicated that EB-PBF–Ti6Al4V alloys manifest higher corrosion resistance relative to wrought counterparts, owing to an increased presence of the β phase in the microstructure. Considering that the EB-PBF samples were optimized from the corrosion point of view, tribocorrosion tests were focused on them. Lapping and superfinishing treatments significantly bolstered bio-tribocorrosion resistance of EB-PBF–Ti6Al4V specimens, leading to a noteworthy 50% positive shift in the corrosion potential of EB-PBF–Ti6Al4V alloy during bio-tribocorrosion testing. Although BSA demonstrated a corrosion-mitigating effect in all conditions, its impact on tribocorrosion properties was negligible.