Correlation of structural properties of commercial DLC-coatings to their tribological performance in biomedical applications

Diamond-like carbon (DLC) films are used increasingly for coating of hip endoprostheses. The term DLC describes not a single material, but a class of materials, each material showing unique properties. Five commercially available DLC-coatings along with conventional thin films used for coating of implants (TiN and CrN) are tested on their wear behaviour by disc on pin test, as well as on their structural composition by multiwavelength Raman spectroscopy. The wear track is analysed by profilometry and weight measurements. The structural analysis includes an estimation of the H-content and the sp3/sp2-ratio by Raman spectroscopy. It is shown that the commercial coatings differ significantly from each other not only in their structure, but also in their tribological performance.