The study of the tribological properties of TiAgN/W₂N coatings in a wide temperature range

TiAgN/W₂N nanoscale multilayered coatings with modulation periods (Λ) ranging from 2 to 7 nm were deposited by magnetron sputtering. The mechanical and wide-temperature tribological properties of the coatings were investigated. All the multilayer coatings exhibited enhanced hardness as compared with TiAgN nanolayer, which was attributed to the decrease in the disclination dipole motion and the grain boundary sliding. With the increase of the modulation period, the hardness decreased due to the reduced stress-accumulated interfaces. The maximum hardness of 27.6 GPa was revealed in TiAgN/W₂N multilayer (Λ = 2 nm). In the temperature range of 25 °C–500 °C, compared with TiAgN nanolayer, all the multilayer coatings exhibited improved friction properties due to the formation of lubricated oxides on the wear track. The lowest friction coefficient of 0.26 was revealed at 500 °C in TiAgN/W₂N multilayer (Λ = 2 nm), whereas the wear rate was 6.7 × 10⁻⁶ mm³·N⁻¹ mm⁻¹. With the increase of the sliding temperature, the reduced friction coefficient and the increased wear rate for multilayer coatings were due to the more lubricative oxides. Sliding against A₂O₃ ball, the main wear mechanism of the coatings was considered to be abrasive wear at room temperature, change to abrasive and oxidation wear at high temperature. (paper)