Microstructure, mechanical and tribological properties of graphite-like carbon coatings doped with tantalum

Highlights: • The Ta-GLC coatings with different Ta contents were prepared by PVD method. • With Ta content increasing, the microstructure became coarser and the content of sp³C in the coatings decreased. • The adhesion strength of the coatings to substrates was significantly improved after Ta doped, but the hardness decreased. • The coating with 4.79 at% Ta content had the lowest wear rate, which was only one third of the value of non-doped GLC coating, ascribed to the synergistic effect of higher adhesion strength, graphitization structure and the formation of TaC and Ta nanoclusters. The tantalum doped graphite-like carbon (Ta-GLC) coatings were obtained by magnetron sputtering. The variations of microstructure, mechanical and tribological properties by Ta content were systematically assessed. The results revealed that as the doping amount of Ta increased, the columnar structure of the coatings became coarser and the content of sp³C in the coatings decreased, and the hardness and elastic modulus of the Ta-GLC coatings were decreased correspondingly. However, the adhesion strength between the coatings and substrates was improved after Ta doping. Besides, the Ta-GLC coating with 4.79 at% Ta content exhibits the lowest wear rate of 2.55 × 10⁻⁸ mm³/Nm, which is approximately only one third of the value of non-doped GLC coating. This was mainly related to the synergistic effect of higher adhesion strength, graphitization structure and the formation of TaC and Ta nanoclusters in the Ta-GLC coating.