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Proyecto Confidencial

[EN] The corrosion and tribocorrosion behavior of an as-cast high carbon CoCrMo alloy immersed in phosphate buffered solution (PBS) and phosphate buffered solution with bovine serum albumin (PBS + BSA) have been analyzed by electrochemical techniques and surface microscopy. After the electrochemical characterization of the alloy in both solutions, the sample was studied tribo-electrochemically (by open circuit potential, OCP measurements, potentiodynamic curves and potentiostatic tests) in a ball-on-disk tribometer rotating in different sliding velocities. The influence of solution chemistry, sliding velocity and applied potential on the corrosion and tribocorrosion behavior of the CoCrMo alloy has been studied. Anodic current density increases with sliding velocity but wear rate does not change at an applied anodic potential; on the other hand, BSA modifies the wear debris behavior (by agglomerating the debris formed by mechanical removal of particles) thus increasing the mechanical wear volume. Under cathodic conditions, cathodic current density also increases during mechanical contact while the wear rate decreases with sliding velocity and BSA lubricates the contact thus reducing the total wear volume with respect to the non-containing BSA solution. The work shows how the electrode potential critically affects the corrosion and tribocorrosion rates by increasing the wear coefficients at applied anodic potentials due to severe wear accelerated corrosion. (C) 2011 Elsevier Ltd. All rights reserved.

En este trabajo se estudia el comportamiento tribo-electroquímico de una aleación biomédica CoCrMo en fluidos que simulan el suero fisiológico. Para ello se hace uso de un tribómetro acoplado a un dispositivo electroquímico que permite simular simultáneamente solicitaciones mecánicas y electroquímicas sobre la aleación. Se analiza el efecto de la composición química del suero (la influencia de la presencia de una proteína modelo como la albúmina) en los mecanismos de tribocorrosion según los cuales se produce la degradación del CoCrMo. Además se estudia el efecto del potencial aplicado y la velocidad de rotación en la resistencia al desgaste y a la corrosión de la aleación.