Microstructure and tribomechanical properties of multilayer TiZrN/TiSiN composite coatings with nanoscale architecture by cathodic-arc evaporation

Abstract

Multilayer TiZrN/TiSiN coatings were deposited on steel substrate by the cathodicarc evaporation technique. The TiZr (75:25 at. %) and TiSi (95:5 at. %) alloy cathodes served as evaporation sources. Scanning electron microscopy with energy-dispersive spectroscopy, secondary ion mass-spectrometry, X-ray diffraction and X-ray photoelectron spectroscopy were employed to investigate the microstructure, elemental composition, phase state and bonding structure of the deposited coatings. Nanoindentation and ball-on-disk tribology tests were used tomeasure themechanical and tribological features of the coatings, such as hardness, elastic modulus, toughness, friction coefficient and wear rate. The results show that all multilayers were fcc structureswith a strong preferred orientation along (111) plane. The coherent growth of the multilayers contributed to the formation of the fine-grained structure with crystallites of 9.2–11.6 nm size and a lowlevel of residual stresses of- (3.5–5.3) GPa. All multilayer coatings exhibited high hardness up to 38.2 ± 1.15 GPa and elastic modulus up to 430 ± 12.9 GPa, indicating higher resistance against plastic deformation compared to TiZrN and TiSiN films. The result of ball-on-disk wear tests showed that the multilayer sample with the best structural features (modulation period of 20.4 nm, 0.86 at. % of Si, the crystallite size of 9.2 nm and residual stress of- 3.5 GPa)demonstrated the lowest friction coefficient of 0.844 andbetterwear rate of 3.32 10–5 mm3/N m.