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The additive manufacturing (AM) technique can produce Ti-6Al-4V ELI (extra low interstitial) alloy for personalized biomedical devices. However, the Ti-6Al-4V ELI alloy presents poor tribological behavior. Regarding this, coatings are a feasible approach to improve the wear resistance of this alloy. In the literature, the tribological behavior of TiO2 coatings incorporated with Ca and P formed by one-step plasma electrolytic oxidation (PEO) on Ti-6Al-4V ELI alloy processed by AM has not been investigated. Thus, in the present work, it was studied the influence of Ti-6Al-4V ELI alloy processed by AM on the wear resistance and morphologic of the coating obtained by PEO (plasma electrolytic oxidation). In this way, three different voltages (200, 250, and 300 V) were employed for the PEO process and the voltage effect on the properties of the coatings. The coatings were characterized by contact profilometry, scanning electron microscopy, energy-dispersive spectroscopy, the sessile drop method, grazing-incidence X-ray diffraction, and wear tests, on a ball-on-plate tribometer. The increase in applied voltage promoted an increase in roughness, pore area, and a decrease in the pore population of the coatings. In addition, the coatings, mainly composed of anatase and rutile, showed good adhesion to the metallic substrate, and the presence of bioactive elements Ca and P were detected. The thickness of the coatings obtained by PEO increases drastically for voltages higher than 250 V (from 4.50 ± 0.33 to 23.83 ± 1.5 µm). However, coatings obtained with lower voltages presented thin and dense layers, which promoted a superior wear resistance (increase in wear rate from 1.99 × 10−6 to 2.60 × 10−5 mm3/s). Finally, compared to the uncoated substrate, the PEO coatings increased the wear resistance of the titanium alloy obtained by AM, also showing a superior wear resistance compared to the commercial Ti-6Al-4V alloy previously evaluated, being such a positive and promising behavior for application in the area of metallic implants. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate, for the first time, the biocompatibility and antibacterial behavior of coatings obtained by plasma electrolytic oxidation (PEO) on the Ti6Al4V ELI alloy manufactured through the direct metal laser sintering (DMLS) additive manufacturing technique, implanted with two different concentrations of Cu ions by ion plating diversified (IPD). The surface morphology, elemental composition, and phase characteristics of the PEO coatings were investigated by SEM/EDS, GDOES, XRD, and XPS. The cytotoxicity in stem cells and the antibacterial effect were evaluated. The XPS analysis confirmed the successful incorporation of Cu at both concentrations, which appeared in the form of two different chemical components: CuO (92%) and Cu 2 O (8%). Stem cells were able to adhere and spread on the surface of the Ti6Al4V ELI alloy, with or without PEO coatings and ionic implantation of Cu particles; the materials and coatings were not cytotoxic. Quantitative cell viability assays for Staphylococcus aureus and Pseudomonas aeruginosa bacteria did not show significant differences. However, the staining of the viability wells, mainly for S. aureus , indicates a change in the behavior of these bacteria in coatings that contained the implantation of Cu oxides. This research demonstrated the potential that the union of the properties of the substrate manufactured in additive manufacturing (great versatility), PEO coatings (wear resistance and cell viability), and IPD ion implanted Cu particles can have in different applications. • Optimization of surface properties by associating additive manufacture, PEO coatings and IPD process. • From IPD process, it was possible to implant copper ions, mainly forming cupric oxide (CuO). • Ionic implantation of Cu was not cytotoxic for stem cells. • Bacteriological behavior was influenced by the presence of Cu oxides. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) can be used to obtain oxide coatings able to improve the biocompatibility, wear and corrosion properties of metal implants, due to complex morphology and the formation of oxides with the possibility of incorporating bioactive elements. This study aims at producing coatings on Ti-6Al-4V alloys with potential application for bone tissue repairs, evaluating cytocompatibility behavior and the potential for osteogenic differentiation, by using mesenchymal stem cells. Coatings have been produced on Ti6Al4V alloys by PEO with a calcium and phosphate-based electrolyte, by applying the potentials of 200 V (Ti-PEO 200V) and 300 V (Ti-PEO 300V), with a pulsed electrical regime. The SEM/FEG characterization shown that the samples obtained are typically porous, have different thicknesses and roughness, which were found to be dependent on the maximum applied voltage. The bioactive elements (Ca and P) were incorporated into the coatings and their concentrations grew with the maximum applied voltage, as indicated by RBS analysis. In addition, the same analysis indicated that the coatings were mainly composed of Ti oxides. XRD patterns confirmed that the coatings consist mainly of titanium oxides in the rutile and anatase phases. The tribological properties were evaluated by a ball-on-plate tribometer. Both samples show very similar tribological behavior. The wear resistance of Ti-PEO 300V was more impaired by the microcracks present in its morphology and its great surface roughness than the Ti-PEO 200V sample. Biological properties were assessed by studying the cytocompatibility with MSC cells. The coating obtained for the Ti-PEO 200V sample showed a great cytocompatibility level and initial adhesion, as well as an innate ability for osteo-differentiation of MSCs, displaying considerable potential for usage as bone-repair applications. [Display omitted] • PEO coatings were constituted by rutile and anatase phases. • Ti-PEO 200V showed superior wear resistance compared to that Ti-PEO 300V. • Wear resistance was compromised by the formation of cracks in the Ti-PEO 300V. • Ti-PEO 200V sample showed better behavior with MSCs compared to the Ti6Al4V. [ABSTRACT FROM AUTHOR]