Design and evaluation of powder metallurgy titanium surfaces modified by colloidal techniques and diffusion processes for biomedical applications

Proceeding of: World PM2016 Congress (New materials and applications: Biomedical applications)The aim of this work was the modification of the composition and surface microstructure of powder metallurgy titanium to improve the wear resistance and reduce the elastic modulus while maintaining the corrosion behavior, characteristics needed for biomedical applications. For this purpose, Mo and Nb coatings were produced by colloidal techniques. Stable aqueous suspensions were prepared from micro-sized powder of Mo and Nb particles, deposited onto the powder metallurgy titanium substrates (green or sintered). After a heat treatment to promote the diffusion and the consolidation of the layers, microstructural changes were obtained. In the case of green substrates, the co-sintering process provides a diffusion depth of 85-100 micron. In the as-sintered case, a uniform depth of 40-65 microns was reached. The surfaces were characterised by micro-hardness, corrosion and tribocorrosion testing, and the results showed that hardened surfaces presented lower tendency to corrosion both under static conditions and under sliding.Funds were provided by Spanish Government (programme MINECO, ref. MAT2012-38650-C02-01), Regional Government of Madrid (programme MULTIMAT-CHALLENGE, ref. S2013/MIT-2862) and Institute of Álvaro Alonso Barba (IAAB) for the research stay in CMEMS-UMINHO (University of Minho)

A promising method to develop TiO2-based nanotubular surfaces on Ti-40Nb alloy with enhanced adhesion and improved tribocorrosion resistance

Although TiO2 nanotubes have unique properties making them attractive for variety of applications, their poor adhesion to the substrate is a major limitation. In order to overcome this limitation, a facile route, combination of a two-step anodic treatment and heat treatment was applied in order to develop a well-adhered TiO2-based nanotubular surface on Ti-40Nb alloy. The adhesion of the nanotubular layer was evaluated by Daimler-Benz Rockwell C test. Corrosion and tribocorrosion behavior was investigated in phosphate-buffered saline solution (PBS) at body temperature. Corrosion behavior was examined by potentiodynamic polarization and electrochemical impedance spectroscopy whereas tribocorrosion behavior was evaluated by reciprocating sliding against an alumina ball at open circuit potential. Results showed that the adhesion, corrosion, and tribocorrosion behavior of the nanotubular layer was drastically improved with the combination of a two-step anodic treatment and heat treatment.This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020, together with M-ERA-NET/0001/2015 and PCIN-2016-123 project. I. Çaha is grateful for the financial support through a Ph.D. grant under the NORTE-08-5369-FSE-000012 project, and mobility program under INTERREG VA España Portugal (POCTEP) territorial cooperation programme (Project ref: 0300_NANOGATEWAY_6_P)