Effects of electrochemical and thermal oxidation on the behaviour of some biomaterials in simulated body fluids

Abstract

The effects of electrochemical and thermal oxidation on the behaviour of Ti and its implant alloys Ti-5Al-4V and Ti-6Al-4Fe in Ringer solution are investigated in this paper, using microscopic observations, microhardness measurements, electrochemical impedance spectroscopy (EIS) and long-term monitoring of the open circuit potentials. The microhardness values increased with increasing load, showing the existence of a porous layer; no differences between the applied treatments were observed, revealing the same composition and average depth of the oxide layers. EIS spectra exhibited a two-step process, namely an oxide with two layers: a porous, outer oxide and a barrier inner oxide; some differences appeared in time, due to the apatite nucleation. Statistical analysis of the open circuit potentials for bare Ti and Ti-5Al-4V and Ti-6Al-4Fe alloys supplied histograms, scatter diagrams, regression equations and determination coefficients. A good percent of credibility it resulted and a prognosis can be made.