Improvement of the Corrosion Resistance of Biomedical Zr-Ti Alloys Using a Thermal Oxidation Treatment
Javier Izquierdo,
Daniel Mareci,
Georgiana Bolat,
Juan J. Santana,
Raquel Rodríguez-Raposo,
Luis C. Fernández-Mérida,
Liviu Burtan,
Lucia C. Trincă,
Ricardo M. Souto
Affiliations
Javier Izquierdo
Institute of Material Science and Nanotechnology, Universidad de La Laguna, E-38200 La Laguna (Tenerife, Canary Islands), Spain
Daniel Mareci
Department of Chemical Engineering, Technical University “Gheorghe Asachi” of Iasi, Faculty of Chemical Engineering and Environmental Protection, D. Mangeron, 700050 Iasi, Romania
Georgiana Bolat
Department of Chemical Engineering, Technical University “Gheorghe Asachi” of Iasi, Faculty of Chemical Engineering and Environmental Protection, D. Mangeron, 700050 Iasi, Romania
Juan J. Santana
Department of Process Engineering, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, E-35017 Las Palmas de Gran Canaria, Spain
Raquel Rodríguez-Raposo
Institute of Material Science and Nanotechnology, Universidad de La Laguna, E-38200 La Laguna (Tenerife, Canary Islands), Spain
Luis C. Fernández-Mérida
Institute of Material Science and Nanotechnology, Universidad de La Laguna, E-38200 La Laguna (Tenerife, Canary Islands), Spain
Liviu Burtan
Clinics Department, “Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, Str. Aleea M. Sadoveanu, no. 8, 700490 Iasi, Romania
Lucia C. Trincă
Exact Sciences Department, “Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, Faculty of Horticulture, Str. Aleea M. Sadoveanu, no. 3, 700490 Iasi, Romania
Ricardo M. Souto
Institute of Material Science and Nanotechnology, Universidad de La Laguna, E-38200 La Laguna (Tenerife, Canary Islands), Spain
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.
