San Daniele del Friuli, Italy
San Daniele del Friuli, Italy

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Marin E.,University of Udine | Marin E.,Kyoto Institute of Technology | Offoiach R.,University of Udine | Regis M.,LimaCorporate | And 3 more authors.
Materials and Design | Year: 2016

A wide array of treatments have been applied to improve the tribological behavior of titanium alloys, in particular coatings and diffusive nitrogen treatments. Hybrid technologies based on diffusive treatments and subsequent deposition of PVD coatings may further improve the overall tribological resistance. In this work, conventional PVD coatings of CrN or TiCN, deposited on Ti-6Al-4. V substrates, have been characterized and then combined with two thermal diffusive treatments: nitriding and carburizing. Post-treatment surface morphologies have been studied by means of Scanning Electron Microscopy and Stylus Profilometry. In-depth composition profiles have been obtained using Glow Discharge Optical Emission Spectrometry and localized Energy Dispersive X-Ray Diffraction. The micro-hardness and adhesion properties of the different treatments have been evaluated using Vickers micro-hardness tests at different load conditions and confronting the hardness vs load profiles. The tribological behavior of the different treatments has been tested in dry conditions in alternate pin-on-flat configuration. The standalone PVD coatings showed a limited tribological resistance due to the low hardness of the substrate, which resulted in fractures and delamination. The combination of a hardening process followed by a deposition of a PVD coating showed to strongly improve the tribological resistance of Ti-6Al-4. V. © 2015 Elsevier Ltd.

Marin E.,University of Udine | Pressacco M.,LimaCorporate | Fusi S.,LimaCorporate | Lanzutti A.,University of Udine | And 2 more authors.
Materials Science and Engineering C | Year: 2013

In this work, two different cellular solid structures, obtained by EBM using grade 2 Titanium powders, were investigated. Relative density was evaluated comparing different methods, the mean diameter of the singular open porosity was calculated by SEM image post-processing; the chemical composition was evaluated using Energy Dispersive X-Ray Spectroscopy (EDXS); the microstructure and grain dimension were investigated using chemical etching and, the mechanical properties were investigated using UMTS 810 Materials Test System. The mean porosity values resulted to be similar to spongy bone (around 77% for sample A and 89% for sample B). The mean diameter of the single porosity resulted to be 640 μm for A and 1250 μm for B. The Vickers microhardness results were homogeneous among the structure and the chemical etching showed a complex microstructure characterized by irregular shaped grains. Sample A, as expected, is more resistant than sample B, while sample B shows a lower elastic modulus. © 2013 Elsevier B.V.

Benazzo F.,University of Pavia | Botta L.,University of Pavia | Scaffino M.F.,University of Pavia | Caliogna L.,University of Pavia | And 3 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2014

Trabecular Titanium (TT) is an innovative highly porous structure that imitates the morphology of trabecular bone with good mechanical properties. Adipose-derived stem cells are a multipotent cell population that can be used in regenerative medicine, in particular, for bone therapeutic applications. The ability of TT to induce the osteogenic differentiation of human adipose derived stem cells (hASCs) in the absence of osteogenic factors was evaluated using molecular biological, biochemical, and immunohistochemical methods. At 7 and 21 days from differentiation, the hASCs grown on TT scaffolds showed similar expressions of alkaline phosphatase (ALP) and Runx-2 both in the presence and in the absence of osteogenic factors, as well as at transcript and protein levels. hASCs cultured on monolayer in the presence of the medium obtained from the wells where hASCs/scaffold constructs were cultured in the absence of osteogenic factors differentiated towards the osteogenic phenotype: their gene and protein expression of ALP and Runx-2 was similar to that of the same cells cultured in the presence of osteogenic factors, and significantly higher than that of the ones cultured in growth medium. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2061-2071, 2014. © 2013 Wiley Periodicals, Inc.

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