A comparative study of the structural, mechanical and tribological characteristics of TiSiC-Cr coatings prepared in CH4 and C2H2 reactive atmosphere by cathodic vacuum arc

The coatings were found to be formed with nano-scale composite structures consisting of carbide crystallites (grain size of 3.1-8.2 nm) and amorphous hydrogenated carbon. The experimental results showed significant differences between the two coating series, where the films formed from C2H2 exhibited markedly superior characteristics in terms of microstructure, morphology, hardness, friction behaviour and wear resistance. For the coatings prepared using CH4, the measured values of crystallite size, hardness, friction coefficient and wear rate were in the ranges of 7.2-8.2 nm, 26-30 GPa, 0.3-0.4 and 2.1-4.8 × 10−6 mm3 N−1 m−1, respectively, while for the coatings grown in C2H2, the values of these characteristics were found to be in the ranges of 3.1-3.7 nm, 41-45 GPa, 0.1-0.2 and 1.4-3.0 × 10−6 mm3 N−1 m−1, respectively. Among the investigated coatings, the one produced using C2H2 at the highest flow rate (130 sccm) exhibited the highest hardness (45.1 GPa), the lowest friction coefficient (0.10) and the best wear resistance (wear rate of 1.4 × 10−6 mm3 N−1 m−1).