Corrosion behavior of Ti–Ta–Nb alloys in simulated physiological media Ahmad Ivan Karayan a,b,c , Sang-Won Park b,c , Kwang-Min Lee a, ⁎ a Department of Materials Science and Engineering, Research Institute for Functional Surface Engineering, Chonnam National University, Gwangju 500-757, South Korea b Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju 504-190, South Korea c Dental Science Research Institute and BK21 Project, School of Dentistry, Chonnam National University, Gwangju 504-190, South Korea Received 8 April 2007; accepted 11 October 2007 Available online 17 October 2007 Abstract The purpose of this research was to study the corrosion behavior of Ti-8Ta-3Nb and Ti-10Ta-10Nb in simulated physiological media in comparison to that of CP Ti and Ti-6Al-4V. In the Ringer's solution, Ti-8Ta-3Nb exhibited a higher passive current density than CP Ti and the other Ti-based alloys. Increasing the alloying additions of Ta and Nb to Ti successfully suppressed the oxygen evolution, lowered the passive current density, and shifted the corrosion potential in the noble direction. While the current densities of CP Ti, Ti-6Al-4V, and Ti-8Ta-3Nb significantly increased at a potential N 1.0 V SSC , the current densities of Ti-10Ta-10Nb tended to remain constant. The deconvolution of the O 1s peaks for Ti-10Ta- 10Nb showed the peaks of O 2- , OH - and H 2 O. However, Ti-8Ta-3Nb only showed the peaks of O 2- and OH - . The superior property of the passive film on Ti-10Ta-10Nb, in comparison to that on Ti-8Ta-3Nb, was attributed to the presence of the hydrate group inside the passive film. © 2007 Elsevier B.V. All rights reserved. Keywords: Corrosion; Passive current density; Passive film; Titanium; Tantalum; Niobium 1. Introduction Ti and Ti-based alloys have been widely used as implant materials due to their good mechanical properties and corrosion resistance. The good corrosion resistance of Ti and its alloys is due to the presence of a protective and self-adherent oxide film, which is mainly composed of titanium dioxide (TiO 2 ) [1–5]. Ti-6Al-4V is the Ti-based alloy the most frequently used as an implant material. However, some authors have reported that vanadium is toxic to the human body [6,7]. This concern has led to the development of vanadium-free titanium implant alloys with mechanical and corrosion properties similar to those of Ti-6Al-4V. Due to the detrimental effect of vanadium, Semlitsch [8] developed Ti-6Al-7Nb alloy as an alternative and found that the corrosion resistance of this alloy was second only to that of CP Ti. The present authors [9–11] proposed using Ti-8Ta-3Nb and Ti-10Ta-10Nb to replace Ti-6Al-4V in biomaterials. Unfortu- nately, no detailed information on the corrosion behavior of these alloys in Ringer's solution could be found in the literature. The objective of this research was to study the corrosion behavior of Ti-8Ta-3Nb and Ti-10Ta-10Nb in simulated physiological fluid in comparison to that of CP Ti and Ti-6Al-4V. 2. Experimental procedures The materials used in this experiment were CP Ti (purity 99.99%), Ti-6Al-4V (Ti 90.30%, Al 5.30%, V 4.30%, impurities 0.10% max), Ti-8Ta-3Nb (Ti 88.50%, Ta 8.50%, Nb 2.90%, impurities 0.10% max), and Ti-10Ta-10Nb (Ti 79.90%, Ta 10.10%, Nb 9.90%, impurities 0.10% max). The corrosion behavior of CP Ti and the Ti-based alloys was studied in Ringer's solution: 9.000 g/l NaCl, 0.240 g/l CaCl 2 , 0.430 g/l KCl, 0.200 g/l NaHCO 3 . The test solution was prepared from high purity 18 MΩ cm water. All of the specimens were sequentially polished with 220-, 600-, 1000-, 1500-, and 2000-grit silicon carbide (SiC) abrasive papers and then with 0.1-μm diamond paste. After polishing, the specimens were ultrasonically cleaned in acetone for 10 min Available online at www.sciencedirect.com Materials Letters 62 (2008) 1843 – 1845 www.elsevier.com/locate/matlet ⁎ Corresponding author. E-mail address: kmlee@chonnam.ac.kr (K.-M. Lee). 0167-577X/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2007.10.028