Closed-field unbalanced and balanced magnetron sputtering was used to deposit nanocrystalline TiC (nc-TiC)/amorphous carbon (a-C) nanocomposite coatings with hydrogenated or hydrogen-free a-C matrix, respectively. The contents of Ti and C in the coatings have been varied over the full range of interest (7–45 at.% Ti) by changing the flow rate of acetylene gas or the locations of substrates relative to the center of C/TiC targets. Different levels of bias and deposition pressure were used to control the nanostructure. The nanocomposite coatings exhibit hardness of 5–35 GPa, hardness/E-modulus ratio up to 0.15, wear rate of 4.8_10_17 m3/N m lap, friction coefficient of 0.04 under dry sliding and strong self-lubrication effects. The nanostructure and elemental distribution in the coatings have been characterized with cross-sectional and planar high-resolution transmission electron microscopy (HRTEM) and energy-filtered TEM. The influence of the volume fraction and size distribution of nc-TiC on the coating properties has been examined. The nc-TiC/a-C(:H) nanocomposite coatings have been successfully deposited by magnetron sputtering, which consist of TiC nanocrystallites embedded in amorphous carbon matrix. Small TiC particle size (2 nm) and low volumetric fraction (~0.3) result in very homogeneous micro/nanostructures of the nanocomposite coatings that combine low friction with high toughness and wear resistance. The columnar structure varies as a function of Ti content and substrate bias, and can be restrained to achieve supertoughness in these nanocomposite coatings. The H/E ratio is mainly dominated by C content and reaches high values above 0.1 at high C contents, which result in high wear resistance. Self-lubrication can be achieved at high volumetric fraction of amorphous carbon matrix together with homogeneously distributed TiC nanocrystallites.
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