Electrochemical behaviour of zirconium and titanium with different surface modification processes in simulated body fluid

SILVIA CERÉ; ANDREA GOMEZ SANCHEZ; GUSTAVO DUFFÓ

Niza, Francia

Congreso; 61st Annual Meeting of the International Society of Electrochemistry; 2010

International Society of Electrochemistry

The surface of biomaterials is in contact with the living tissues in the first stages of osseointegration, and the success or failure of the prosthesis depends of the reactions that can occur in the surface. The improvement of biocompatibility of permanent implant materials by means of surface modification is one of the most currently studied topics in the field of biomaterials. Titanium and its alloys are the most widely used biomaterials for permanent implants applications. Zirconium is presented in this study as an alternative to titanium, based on its excellent corrosion resistance and biocompatibility. Both metals belong to the so called valve metals. Its corrosion resistance is mainly due to a surface oxide thin film present in air and oxygenated electrolytes. These films have thickness of a few nanometers, are strongly adhered to the metal substrates and acts as a barrier against corrosion. In this study several surface modification processes, such as immersion in concentrated peroxide solution, potentiostatic anodization in phosphoric acid and cathodic electrodeposition of Ca-P compounds, have been conducted on cp titanium (grade 2) and zirconium (Zr 702) in order to determine the best surface conditioning that promote rapid osseointegration on this materials. Complementary surface characterization techniques were used to determine the changes on surface with each process.  Electrochemical impedance spectroscopy and potentiodinamic anodic polarization tests were conducted to characterize the electrochemical behavior after each modification process in simulated body fluid solutions. Anodization in acidic media results in thickening of the oxide surface film, that increases the corrosion resistance of both materials in SBF solutions. Phosphorous is incorporated to the anodic oxide film as phosphate. Peroxide immersion leads to thickening of titanium oxide film, evidences by change in the surface sample color. In zirconium, no evidences of thickening of oxide film was found, but an improvement of the barrier effect of the surface film was determined by the electrochemical tests. The electrodeposition slighty affects electrochemical response of zirconium, enhancing the passivity range of the material.