INVESTIGADORES
CERE silvia
congresos y reuniones científicas
Título:
Corrosion Improvement of Surgical Grade Stainless Steel by Sol-Gel Hybrid Coatings Containing SiO2 Nanoparticles and Glass-ceramic Particles
Autor/es:
S. CERÉ; A. GOMEZ SANCHEZ; G. DUFFO
Lugar:
Niza, Francia
Reunión:
Congreso; 61st Annual Meeting of the International Society of Electrochemistry; 2010
Institución organizadora:
International Society of Electrochemistry
Resumen:
Titanium and its alloys are the most widely
used biomaterials for permanent implants applications. Zirconium is presented
as an alternative to titanium, based on its excellent corrosion resistance and
biocompatibility. Both metals belong to the so called valve metals. Their
corrosion resistance is mainly due to a thin surface oxide film present in air
and oxygenated electrolytes. These films are strongly adhered to the metal
substrates and acts as a barrier against corrosion.
Since the implant surface is the region in contact
with living tissues, the characterization of the surface film is of great
interest since the success or failure of the prosthesis greatly depends of the
reactions that can occur on the surface. The surface modifications in order to
improve biocompatibility of permanent implant materials are topics of concern
in the field of biomaterials.
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 as well as to evaluate the barrier effect against the corrosive
environment. Complementary surface
characterization techniques were used to determine the changes on surface after
each process.
Electrochemical
impedance spectroscopy and potentiodynamic anodic polarization tests were
conducted to characterize the electrochemical behavior after each modification
process in simulated body fluid solutions (SBF). Equivalent circuit models were
developed to characterize de film structure from EIS results.
Anodization in phosphoric
acid 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 slightly affects electrochemical response
of zirconium, enhancing the passivity range of the material.