COMPARISON OF STRUCTURE AND MECHANICAL PROPERTIES OF nc-TiC/a-C(:H) AND nc-(Ti,Ni)C/a-C(:H) COATINGS
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| Year of publication | 2015 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Nanocomposite coatings composed of nanocrystalline grains of titanium carbide embedded in an amorphous carbon matrix, nc-TiC/a-C(:H), are widely studied due to their mechanical properties such as high hardness [1]. One of the main parameters that determines the final mechanical properties of nc-TiC/a-C(:H) coating system is the relative content of nanocrystalline and amorphous phase. Selective doping of this system by a non-carbide forming element such as nickel is a possible tool for influencing this parameter [2]. Hybrid PVD-PECVD process of titanium target sputtering in a mixture of acetylene and argon was used to deposit nc-TiC/a-C(:H) coatings [3]. Titanium-nickel (92.5 % Ti, 7.5 % Ni) target was used for preparation of nickel doped coatings. Varying acetylene flow rate was used in order to prepare coatings with different content of C in coatings. Several sets of Ni-free nc-TiC/a-C(:H) and Ni-dopped nc-TiC/a-C(:H) coatings were prepared and compared. Several different analyses were used for the determination of the influence of nickel doping on the properties of the deposited coatings. Composition of coatings was determined using EDX technique, the size of TiC grains and the lattice parameter was determined by grazing angle of incidence X-ray diffraction (GIXRD). Coatings were furthermore analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy to determine and also to quantify the present bonds. Fischerscope H100 depth sensing indenter equipped with a Berkovich tip was used for evaluation of hardness of the coatings. Optical emission spectroscopy was used for analysis of properties of plasma during deposition process. There are only peaks corresponding to TiC and no peaks corresponding to Ni in the XRD difractograms. This suggests that that nickel atoms are bonded only in the TiC grains forming (Ti,Ni)C grains, as was proposed by Lewin [2]. The sizes of the TiC and (Ti,Ni)C grains as well as the lattice parameters obtained from XRD analysis exhibit almost no dependence on nickel content of the coatings in the studied range, although difference between the hardness of nickel-free and nickel-doped sets of coatings was observed. This research has been supported by the project CZ.1.05/2.1.00/03.0086 funded by European Regional Development Fund, project LO1411 (NPU I) funded by Ministry of Education, Youth and Sports of Czech Republic and GACR P205/12/0407 project. |
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