Electrochemical behavior of titanium‐tantalum alloys in sulfuric acid solutions

Abstract

Titanium exhibits a good corrosion resistance in oxidizing acids and neutral media but it is severely attacked in reducing acids. On the contrary, tantalum presents an excellent resistance in both oxidizing and reducing acids, but its high cost limits its use to very aggressive conditions. The titanium-tantalum alloys are promising materials for use in reducing acids, due to their lower cost and density when compared to tantalum, and their higher corrosion resistance when compared to titanium. Titanium-20, 40, 60 and 80 wt% tantalum alloys were prepared by arc-melting and their microstructures were characterized by scanning electron microscopy and Xray diffractometry. Their electrochemical behaviors were studied in 20 to 80 wt% sulfuric acid solutions at room temperature, using open-circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy. Different behaviors were observed depending on the tantalum content and acid concentration. A clear tendency of increase in corrosion resistance with the increase of tantalum content is observed, especially in 80 wt% sulfuric acid solutions.

Ideal Hexagonal Order: Formation of Self-Organized Anodic Oxide Nanotubes and Nanopores on a Ti–35Ta Alloy

“…The oxide layers provide a very high corrosion resistance to surfaces, as Ta 2 O 5 is significantly more resistant than TiO 2 in almost any environment but particularly under cathodic reductive conditions. 24,25 Moreover, the alloy provides excellent biocompatibility but with a considerably lower average weight than pure Ta. Therefore, various Ti-Ta alloys are explored as candidates for biomedical implant materials.…”

Characterization of Ti‐Ta Alloys Synthesized by Cold Crucible Levitation Melting

“…It was recently pointed out that, due to the relatively high cost of Ta, Ti-Ta alloys are also promising materials in a severe chemical environment as they present a higher corrosion resistance than pure Ti in reducing acid. [13,14] Thus, the Ti-Ta alloys are potentially interesting for many applications including chemistry industries, marine environment and biomedical devices.Titanium and tantalum are however difficult to alloy in usual furnaces because they are very reactive metals having a great difference in melting point and specific gravity. To synthesize alloys from the Ti-Ta system with a wide range of composition, we have developed the cold crucible levitation melting (CCLM) technique, which is well known to be an efficient method in order to melt metals with a high melting point and to obtain uniform chemical composition without contamination.…”

“…To synthesize alloys from the Ti-Ta system with a wide range of composition, we have developed the cold crucible levitation melting (CCLM) technique, which is well known to be an efficient method in order to melt metals with a high melting point and to obtain uniform chemical composition without contamination. [14] In the present work, the microstructure and the mechanical properties (microhardness measurements and compression tests) of stable Ti-Ta alloys synthesized by CCLM in the whole range of composition are presented. As these alloys are potentially interesting for biomedical applications, electrochemical experiments in a simulated body fluid were carried out.…”

“…It was recently pointed out that, due to the relatively high cost of Ta, Ti-Ta alloys are also promising materials in a severe chemical environment as they present a higher corrosion resistance than pure Ti in reducing acid. [13,14] Thus, the Ti-Ta alloys are potentially interesting for many applications including chemistry industries, marine environment and biomedical devices.…”

Investigation of passivation and galvanic corrosion of Ti–Nb alloys and pure titanium

“…In order to develop implant materials that can be applied in practical use, it is important to understand the relationship between the passivation layer and the galvanic corrosion of the implant when coupled with abutment material. Corrosion resistance is closely related to the ability to form a passive oxide layer . Passive oxide layer effectively protects the inner substrate from further corrosion, by avoiding direct contact of the Ti alloy with the biofluid.…”