We have investigated by transmission electron microscopy (TEM) a biocompatible, diamond like carbon (DLC) coating and its interface to an alumina/alumino-silicate glass composite substrate. According to our TEM results, the DLC is composed of two essentially different regions: Up to 80nm from the interface a high density of SiC grains is present, some of which are directly bound to the substrate. The particles are embedded in an amorphous C-matrix. With increasing distance from the interface SiC grains are not present, but nanocrystalline diamond particles (up to 10Vol%) are embedded in that matrix. It is this heterogeneous microstructure that yields: (ⅰ) the good adhesion, based upon the interface stabalizing SiC grains and (ⅱ) high hardness and wear resistance, based upon the diamond nanocrystals in the coating.
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