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Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of material research aimed at reducing the friction of the functional surfaces of titanium implants, and thus extending their lifetime to reoperation. Nitrogen ion beam assisted deposition of a carbon-based nanolayer was applied to modify the surface properties (i.e. sliding and wear) of Ti6Al4V biomedical titanium alloy. Ion bombardment caused structural changes, which led to an increase in surface hardness by a factor of 1.86 in comparison with a surface modified by a carbon nanolayer without nitrogen ion bombardment. An analysis of the chemical composition showed that the modified surface is composed of a carbon-based nanolayer, a mixed interface, and a nitrogen-enriched sublayer. Raman spectroscopy showed the DLC character of the carbon-based nanolayer with sp2 rich bonds. A TiN compound was detected by X-ray diffraction in the modified surface area. A very low friction coefficient below 0.1 was maintained for a normal load of 2N. The sliding behavior of the head (Ti6Al4V) and the shell (PEEK) tested on a joint wear simulator showed that surface modification of the head of the implant under optimized deposition conditions provides protection for the functional surfaces, leading to a reduction in wear and a substantial increase in lifetime.
Keywords: Nanolayer, friction, nanohardness© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.