C. Valero Vidal

Polytechnical University of Valencia, Valenza, Valencia, Spain

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Publications (5)3.55 Total impact

  • C. Valero Vidal, A. Igual Muñoz
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    ABSTRACT: The behaviour of the CoCrMo alloy was studied under different experimental conditions of solution pH, chemical composition (phosphate buffer solution with and without addition of bovine serum albumin) and aeration (presence and absence of oxygen in the solution). With this purpose, electrochemical techniques such as open circuit measurements (OCP), potentiodynamic curves, potentiostatic tests and electrochemical impedance spectroscopy (EIS) were employed.The results show that the general corrosion behaviour of CoCrMo alloy depends on the solution pH. Thus, the effect of BSA and the aeration conditions are related to the solution pH. At pH 3 no influence of BSA was observed in deoxygenated solutions which imply that BSA acts over the oxygen reduction reaction in acidic media. On the contrary, a noticeable influence of BSA addition was observed at pH 7.4 (independently on the gas content). Finally, at pH 10, the influence of BSA was only significant in oxygenated solution. It was found that H2PO4− favours the formation of passivating compounds which improves the resistance of the CoCrMo alloy to passive dissolution. Therefore, when the concentration of the H2PO4− increases (when pH decreases) the polarization resistance of the alloy also increases. On the other hand, the oxygen (aerated conditions) decreases the polarization resistance of the alloy in all the studied conditions.
    Electrochimica Acta - ELECTROCHIM ACTA. 01/2011; 56(24):8239-8248.
  • C Valero Vidal, A Olmo Juan, A Igual Muñoz
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    ABSTRACT: The adsorption of bovine serum albumin (BSA) onto CoCrMo surface has been studied as a function of concentration of BSA and temperature by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) technique was used to investigate the interfacial behaviour of BSA at open circuit potential (OCP). The charge transfer resistance was very sensitive to the amount of adsorbed protein, indicating that the adsorption process was accompanied by the transfer of charge and influenced the mechanism and kinetics of the corrosion reaction. At all the temperatures studied, adsorption of BSA onto the CoCrMo surface was successfully described with a Langmuir adsorption isotherm. EIS study was also carried out for determine the surface charge density, resulting from protein adsorption, and it was shown to be directly proportional to the amount of adsorbed protein (surface concentration). Thermodynamic data of adsorption was obtained for analyzing the adsorption of BSA onto CoCrMo surface. Gibbs free energy of adsorption, DeltaG(ADS) values, for BSA in the investigated temperature range (-51kJmol(-1)) showed that the molecules have a strong affinity for the CoCrMo surface. Enthalpy (DeltaH(ADS)) and entropy (DeltaS(ADS)) of adsorption suggested that the adsorption process of BSA onto the CoCrMo surface is an endothermic process and the molecule suffers structural changes when adsorbing on the metallic surface.
    Colloids and surfaces B: Biointerfaces 10/2010; 80(1):1-11. · 3.55 Impact Factor
  • C. Valero Vidal, A. Igual Muñoz
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    ABSTRACT: Adsorption of bovine serum albumin (BSA) on CoCrMo surface was studied by electrochemical techniques in order to determine the mechanism of protein adsorption at different surface conditions (which are reached by considering different passivation times) in phosphate buffered solution (PBS). At open circuit potential (OCP), adsorption kinetic was influenced by surface passivation when passivation time was lower than 1 h, whereas, at higher passivation times, no apparent modification in the kinetic mechanisms of adsorption was observed. On the other hand, at a passive applied potential, the BSA addition decreased the passivation kinetics of the process at all the passivation times.
    Electrochimica Acta. 01/2010;
  • C. Valero Vidal, A. Igual Muñoz
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    ABSTRACT: CoCrMo alloy are one of the most important biomaterials for orthopaedic applications, widely used in total joint replacements. The thermal treatments applied to CoCrMo alloys modifies the microstructure of the alloy and change the electrochemical and mechanical properties of the biomaterial. Thus, the aim of this research is to characterize the electrochemical behaviour of CoCrMo alloy depending on the thermal treatment at different applied potentials (according to the cathodic, anodic and transpassive electrochemical domains of the alloy).Metallographic study and electrochemical techniques such as potentiodynamic curves, potentiostatic tests at different potentials (selected according to the electrochemical regions of the potentiodynamic curves) and electrochemical impedance spectroscopy (EIS) are employed to characterize the CoCrMo alloy after three different thermal treatments in simulated body fluid (bovine serum solution).The same corrosion mechanisms were observed for the CoCrMo alloy under the three thermal treatments at different applied potentials, however, the rate of the corrosion reactions which take place on the metallic surfaces depends on those thermal treatments and it is related to the amount of carbide inclusions. At passive potentials the study reveals that the properties of the passive layer depend on the microstructure of the alloy. EIS results show that the resistance of the passive layer in bovine serum solution increased with the carbides solubilisation.
    Electrochimica Acta. 02/2009;
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    C. Valero Vidal, A. Igual Muñoz
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    ABSTRACT: The aim of this research is to compare the electrochemical behaviour of two biomedical alloys, AISI 316L and CoCrMo in simulated body fluids. This comparison is focused on the influence of solution chemistry and immersion time on the passive behaviour using electrochemical techniques, potentiodynamic curves, potentiostatic tests and electrochemical impedance spectroscopy (EIS).Influence of albumin, used as model protein, on both biomaterials depends on the nature of the alloy. It decreases the corrosion resistance of AISI 316L while increases the corrosion resistance of CoCrMo. Although it is known that it adsorbs on both alloys, properties of the passive layer modifies the effect of albumin. On the contrary, precipitation of phosphate ions could explain the highest resistance values in the phosphate solutions on both cases.The study shows that the electrochemical behaviour of CoCrMo shows higher transfer resistance and lower capacitance which means thicker and more protective passive films than AISI 316L. However, differences between both alloys disappear with time depending on the solution chemistry.
    Corrosion Science. 01/2008;

Publication Stats

26 Citations
3.55 Total Impact Points

Institutions

  • 2008–2011
    • Polytechnical University of Valencia
      Valenza, Valencia, Spain