Ca-O-modified diamond-like carbon coatings synthesised by a direct current discharge

In order to expand the applicability of diamond-like carbon coatings (DLC) for biomedical purposes, the addition of calcium compounds which could influence bone formation may be of considerable relevance. The intention of this study is to gain first information about the influence of Ca-O-incorporation on the mechanical and structural properties of DLC. The generation of the conventional DLC and the Ca-O-DLC of approximately 500 nm thickness was carried out by using a direct current discharge for plasma formation. For the deposition of Ca-O-DLC, gaseous hydrocarbon precursor (methane) and CaO-H2O vapour were decomposed together in the plasma chamber. The characterisation of the DLC structure was carried out by Raman and IR-spectroscopy as well as XPS measurements. For characterising the mechanical behaviour. universal hardness and resistance against scratching were illuminated. Dependent on the chosen relative partial pressure of CaO-H2O valour in the working chamber, the film growing rate, the hardness and structure are influenced. Raman spectroscopy point to an increase of sp(2) crystallite in size and/or number. Calcium can be incorporated into the DLC as carbonate which could promote the biological compatibility. (C) 2001 Elsevier Science B.V. All rights reserved.