Phase composition and structural features of ion-plasma titanium carbide-based coatings

The performance and durability of cutting and technological tools are largely determined by the condition of their surface layer. Titanium carbide-based ion-plasma coatings are of particular interest because of their high hardness, thermal stability, and compatibility with carbide substrates. This study investigates the phase composition and structural features of ion-plasma TiC-based coatings formed under different deposition conditions. A combined thermodynamic and experimental approach was applied, including refinement of p-T-x diagrams for the Ti-C system, X-ray diffraction analysis, Auger electron spectroscopy, and photoelectron spectroscopy. The results showed that the coatings contain both stoichiometric and non-stoichiometric TiCₓ phases together with free and diamond-like carbon, and that their formation strongly depends on acetylene pressure and substrate temperature. At an acetylene pressure of 1.1 Pa, the coating contained about 33 at.% TiC and 67 at.% free carbon, whereas at 0.004 Pa the composition shifted to about 50 at.% TiC and 50 at.% free carbon. The refined p-T-x diagrams were consistent with the experimental observations and proved useful for predicting phase formation and selecting deposition regimes. The study demonstrates that controlled non-stoichiometry can be used to tailor the structure and expected functional performance of TiC-based coatings for cutting and technological applications.

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