Mid Sweden University

Ti-6Al-4V is one of the widely used load-bearing implant materials due to its unique set of combinatorial properties such as biocompatibility and enhanced mechanical properties. However, after being implanted, these biomaterials can trigger difficulties in patients due to infections mainly caused by bacterial adhesion. Their good corrosion performance is mainly explained by the formation of a dense and passive oxide layer on their surface. Nevertheless, this oxide film alone does not have enough surface characteristics like bioactivity, antimicrobial activity, corrosion resistance, osseointegration, roughness, biocompatibility, fatigue, and wear to provide good performance for biomedical applications. For that reason, others surface modifications on these alloys are required. In that direction, the surface modification of plasma electrolytic oxidation (PEO) is of great interest given its low cost and environmentally friendly nature. PEO had been widely studied on Ti-6Al-4V alloys, especially on substrates made by conventional manufacturing like forged. However, currently, most implants are manufactured by additive manufacturing techniques (electron beam melting, selective laser melting) and the effect of PEO on substrates manufactured by these techniques has not been completely studied, especially by the electron beam melting technique. In this work, the morphology, chemical composition, and phase composition of the PEO coatings on substrates manufactured by the EBM technique were analyzed by Scanning Electron Microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS) and X-ray diffraction (XRD). PEO coatings characteristics like thicknesses, pore sizes, and layer homogeneity along the built direction of the printed part and its transversal direction were measured with the purpose to evaluate the effect of the anisotropic of printed substrates over the PEO layer growth. For comparative analysis, PEO coatings on the forged substrates were evaluated to analyze the effect of different microstructures with respect to substrates manufactured by the EBM technique. According to previous microstructure characterization of substrates, the analysis shows a differential growth of the anodic layer on substrates manufactured by EBM due to the presence of beta and alpha phases in Ti-6Al-4V and the difference in grain size related to the build direction of the printed part and its transversal direction.