Improvement of the Corrosion Resistance of Biomedical Zr-Ti Alloys Using a Thermal Oxidation Treatment

Abstract

Binary Zr-Ti alloys spontaneously develop a tenacious and compact oxide layer when their fresh surface is exposed either to air or to aqueous environments. Electrochemical impedance spectroscopy (EIS) analysis of Zr-45Ti, Zr-25Ti, and Zr-5Ti exposed to simulated physiological solutions at 37 °C evidences the formation of a non-sealing bilayer oxide film that accounts for the corrosion resistance of the materials. Unfortunately, these oxide layers may undergo breakdown and stable pitting corrosion regimes at anodic potentials within the range of those experienced in the human body under stress and surgical conditions. Improved corrosion resistance has been achieved by prior treatment of these alloys using thermal oxidation in air. EIS was employed to measure the corrosion resistance of the Zr-Ti alloys in simulated physiological solutions of a wide pH range (namely 3 ≤ pH ≤ 8) at 37 °C, and the best results were obtained for the alloys pre-treated at 500 °C. The formation of the passivating oxide layers in simulated physiological solution was monitored in situ using scanning electrochemical microscopy (SECM), finding a transition from an electrochemically active surface, characteristic of the bare metal, to the heterogeneous formation of oxide layers behaving as insulating surfaces towards electron transfer reactions.

Stability Range of Ti-Zr Alloy for Dental Implants

“…5 presents the surface topography of Ti-20Zr alloy and it reveals the influence of simulated body fluid on the surface of the sample. Can be seen that the passive layer has an external porous film [7,8] which is suitable for oseoinduction growth of the bone. Fig.…”

A Combined Scientometric and Critical Approach in Reviewing TiZr Implant Alloys and Coating Performances

“…7-8). Another study regarding the corrosion resistance of Zr−Ti alloys shows too that the thermal oxidation in air at 500 • C does improve the corrosion resistance and suggests that prior to the use of such alloys as implant materials, a treatment consisting of thermal oxidation in air followed by exposure to a physiological solution should be applied [105].…”

Electrochemical Study and Mechanical Properties of Ti-Zr Alloy for Biomedical Applications

“…It was found out that the alloys possess increased biocompatibility compared to cpTi, proving that they are a great candidate for small-diameter implants. Alternate outcomes were revealed during the examination of the electrochemical behavior of the alloys with titanium and zirconium [16,17]. These studies showed that the alloy passivated more easily in Ringer solution compared to cpTi, having a more stable passive film than Ti [18,19].…”