Abstract

PITYANA, S.L.; BALOYI, N.; TLOTLENG, M.  and  POPOOLA, P.. Laser surface deposition of niobium and titanium-niobium on Ti6A14V substrates for biomedical applications. J. S. Afr. Inst. Min. Metall. [online]. 2019, vol.119, n.4, pp.385-389. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/16/211/2019.

The advantages of using Nb and Ti-Nb coatings for improving the hardness and corrosion resistance of Ti6Al4V were investigated. It has been reported that Ti6Al4V used in orthopaedic implants tends to release toxic Al and V ions into the surrounding tissue. Thin layers of Nb and Ti-Nb were deposited on Ti6Al4V substrates using a laser metal deposition technique. The deposited material was analysed using optical microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy, and X-ray diffraction. The corrosion behaviour of the deposited layers was investigated using a Metrohm Autolab PG Stat101 compact potentiostat at 25°C in simulated body fluid. A Vickers hardness system was used to study the mechanical properties. Both Nb and Ti-Nb coatings exhibited good metallurgical bonding with the substrate. The microstructure and the XRD analyses for the Nb system showed that the a-Nb phase was most dominant, while the Ti-Nb system comprised a mixture of the α and β phases. The average hardness of the Ti6Al4V substrate was 350 HV₀₃, with a slight increase for the Nb coating (363 HV₀₃) and a much higher hardness from the Ti-Nb coating at 423 HV_0.3. The corrosion results show that the deposited Nb was more corrosion-resistant in the solution than either the Ti6Al4V substrate or the Ti-Nb coating.

Keywords : Corrosion; laser surface deposition; niobium (Nb); titanium (Ti); titanium-niobium (Ti-Nb); Ti6Al4V.

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