Hafnium has been suggested as an interesting candidate for orthopaedic applicationsdue to its good biocompatibility and osteogenesis. However, there is a need to further investigate its resistance to wear and corrosion in biological environments if hafnium is to be considered for such applications.The corrosion and tribocorrosion behaviour of hafnium and commercially pure titanium in simulated body fluids were investigated using electrochemical techniques. A ball-on- plate configuration tribometer and a three electrode electrochemical cell were integrated to investigate the tribocorrosion performance of the studied materials. In addition, the effect of micro-motions on the corrosion resistance of the material was also studied. Cyclic polarisation scans, open circuit potential measurements and potentiostatic tests were performed in 0.9% NaCl solution and 25% bovine calf serum solution in order to assess the effect of organic species on the corrosion behaviour of the metal.The results showed that hafnium has a good corrosion resistance due to its passive state in the studied solutions. A tendency to suffer from localised corrosion was observed, but the electrochemical breakdown of the oxide layer was retarded in the presence of proteins. However, the pit formation was enhanced due to the presence of surface imperfections and when the surface was subjected to micro-motions. Tribocorrosion tests showed that hafnium has the ability to quickly repassivate after the oxide layer was damaged; however, it showed higher volumetric loss than CP titanium in the studied wear-corrosion conditions.This study provides an insight into the potential of hafnium for orthopaedic applications.
Godkänd; 2014; 20141210 (emami)