The investigation of corrosion resistance for pearlitic Co-Cr-Mo-C biomedical alloy in simulated body fluid

Toxicity of metallic ions in human body, as consequence of biomaterial corrosion, is one of the most important health concerns in which many researches on widely used biomaterials has been performed so far. Co-Cr-Mo-C biomedical alloy is employed for manufacturing of knee and hip joint prostheses as well as dentistry. The aim of this research is to investigate the corrosion resistance of heat treated Co-Cr-Mo-C biomedical alloy contained the microstructure of full pearlite-like HCP phase, in simulated body fluid (SBF). In this study, metallographic observation, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were utilized to characterize the Co-Cr-Mo-C alloy after heat treating, in simulated body fluid. Absence of passive layer on the surface of heat treated alloy was observed in the potentiodynamic curve. However, the rate of corrosion reactions occurring on the metallic surface increased slightly due to carbide formation. Current density (corrosion rate) moved from 1.549 μA cm-2 to 1.862 μA cm-2. EIS results showed that the redox reactions were charge transfer controlled and 94% increase in improvement efficiency of corrosion resistance (η), enhancement in resistance from 303.1 Ω to 5180 Ω, was caused by carbide precipitation on the preferred sites (HCP phase).

Keywords:

Co-Cr-Mo-C biomedical alloy , corrosion resistance , simulated body fluid (SBF) , electrochemical impedance spectroscopy (EIS) , potentiodynamic polarization , pearlitic HCP phase