Spark plasma sintering of Ti6Si2B-based Ti-Si-B alloys and their corrosion resistance in artificial saliva and SBF media

Abstract

Titanium alloys are widely used for dental, medical, automotive, aeronautic and aerospace applications due to their chemical, physical, biological and mechanical properties. Orthopedic implants of the as-cast and heat-treated Ti–10Si–5B alloy present good bone integration capacity as well as Tiss+Ti6Si2B alloys exhibit higher oxidation resistance than Tiss+Ti5Si3 alloys. In this sense, Ti-8Si-4B, Ti-10Si-5B, Ti-14Si-7B, Ti-20Si-10B, and Ti-22Si-11B alloys (atomic percentage - at.-%) with Ti6Si2B-based microstructures were produced by high-energy ball milling and further spark plasma sintering (SPS) at 1100 °C for 6 min under an uniaxial pressure of 191 MPa. Thus, the corrosion resistance of these SPSed Ti-Si-B alloys was evaluated using potentiodynamic polarization method in different media: artificial saliva (AFNOR NF S90-701) and simulated body fluid (SBF). The SPSed Ti-Si-B alloys were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectrometry (EDS). Porosity tests based on Arquimedes’ principle were also performed to evaluate their porosity and density. Despite the short sintering time, our results have confirmed that fine and dense SPSed Ti-Si-B samples with microstructures based on solid solution Ti (Tiss) and Ti6Si2B phases were produced from mechanically alloyed Ti-Si-B powders. The Ti-22Si-11B alloy containing higher amounts of Ti6Si2B presented lower values of passivation current density (2.69 and 0.08 μA.cm-2) and higher corrosion potential (−0.232 and −0.258 V) when compared to Ti-8Si-4B alloy (2.58 and 0.25 μA.cm-2; −0.396 and −0.339 V) in artificial saliva and SBF media, respectively. Moreover, it demonstrates superior corrosion resistant than Ti-7Zr-20Si-10B, Ti-13Nb-13Zr, Ti-6Al-4V and pure Ti.