Tribocorrosion Behavior of Niobium-Based Thin Films for Biomedical Applications

The current work presents a comparative study of niobium, niobium carbide, and niobium nitride coatings deposited on AISI 316LVM stainless steel. The investigation was based on the synergy between corrosion and wear; therefore, the coating application was focused on future biomedical implants. The experiments were conducted under conditions of simulated biological fluid, with load and speed parameters of an average person. The tribo-corrosion tests were done by adapting an electrochemical cell to a pin-on-disk tribometer. The surfaces were characterized through optical means and scanning electron microscopy while the corrosion phenomenon was studied by potentiodynamic polarization curves. As a result, it was found that these coatings protect the surface against corrosion showing no evidence of degradation and lower corrosion rate value compared with the uncoated steel substrate. Moreover, the coatings show diverse wear mechanisms including abrasion wear and plastic deformation. The microstructure of the niobium coating was modified by the addition of carbon or nitrogen, improving the surface performance. Furthermore, in all the studied cases the coatings showed better behavior in tribo-corrosion phenomena in relation to the AISI 316LVM stainless steel substrate.