Estudo do comportamento eletroquímico das ligas Ti6A14V e CoCrMo em solução salina de NaCl e tampão fosfato-salino (PBS).

Abstract

Nowadays, it has been noticed an increase in the number of surgeries with implants and prostheses, in which it is necessary to use compatible materials with the human organism, called biomaterials. Among them are the biocompatible metals and metal alloys, such as the L605 and TiNi alloys. The metals are widely used in orthopedic prostheses of hip, knee and implants such as the coronary stent because of their physicals properties like a good mechanical resistance. However, after a period of time, metallic implanted materials can undergo a corrosion process and release metallic ions into the body, which can cause various problems for the patient such as toxic reactions and chronic allergies. The objective of this study is to analyze the behavior of two metallic alloys used in implants, Titanium -Aluminum- Vanadium (Ti6Al4V) and Cobalt-Chromium-Molybdenum (CoCrMo). Initially, a working electrode was prepared, from a test specimen of dimensions (1 x 1 x 1) cm³, for each alloy. Solutions of NaCl and PBS (Phosphate Buffer Saline) were used to simulate body fluids to which such materials are subjected. The solutions were maintained at 37°C, their pH at 7.4 and under constant stirring. For the analysis, electrochemical tests were performed: Open Circuit Potential, Electrochemical Impedance Spectroscopy (EIS) and Polarization Curve. The assays occurred with 1, 5, 10 and 24 hours of immersion in each of the solutions. After 24h analysis, images of the surface of the samples were made by Scanning Electron Microscopy technique. From the Nyquist plots, obtained by EIS, it was observed that both alloys in the NaCl and PBS solutions had an increase of the capacitive arc, consequently an increase of the resistance potential of the materials to the electrolytes.