Corrosion Resistance of Passivated NiTi After Long-Term Exposure to Simulated Body Fluids

Abstract

Corrosion resistance of the implant alloy is a very important determinant of its biocompatibility. Both, the environment and the applied surface treatment have a significant influence on corrosion. The main aim of the research was evaluation of corrosion resistance of NiTi alloy after long-term exposure to various simulated body fluids. The evaluation of the electrochemical behavior of NiTi alloy was realized by recording of anodic polarization curves with the use of the potentiodynamic method. The tests were carried out for differently modified surfaces both before and after the 6 months exposure to the simulated body fluids. Surface condition of metal biomaterial determines its corrosion resistance. In the course of the work it was observed that the corrosion resistance of all the samples (with different surface conditions) before long-term exposure is similar. The exposure did not change the corrosion resistance of the NiTi alloy significantly. Only the electropolished samples revealed the decrease of the corrosion resistance. The obtained results could be the basis optimization of physicochemical properties of the NiTi alloy. The future research should be focused on selected specific implants specially with respect to their application features. On the basis of the obtained results it can be stated that the suggested surface treatment can be applicable for NiTi alloys due to the increase of the corrosion resistance. The long-term exposure to the simulated body fluids did not deteriorate the corrosion resistance of the investigated alloy. The proposed surface treatment methods can be applied to implants intended for diverse medical applications, especially in cardiology and urology.