Influence of air oxidation on the properties of decorative NbOxNy coatings prepared by reactive gas pulsing

Abstract

In this work the oxidation resistance of DC reactive sputtered niobium oxynitrides and its influence on the properties of the films are studied. The depositions have been carried out by DC magnetron sputtering with a reactive gas pulsing process. The nitrogen flow was kept constant and the oxygen flow was pulsed. Pulse durations of 10 s produced multilayer coatings with a period of λ = 10 nm. Three sets of films with increasing duty cycle (= on-time of high oxygen flow / pulse duration) have been deposited. The films were subsequently annealed in air at 400, 500 and 600°C, respectively. X-ray diffraction measurements showed a clear and progressive change from a roughly amorphous nature of the films to a crystalline oxidetype compound for those annealed at 600°C, which was consistent with the composition analysis. For annealing temperatures of 500 and 600°C, the coatings presented a significant reduction in hardness, approaching the values characteristic of Nb 2 O 5 -type films. Moreover, the residual stress measurements performed by using the deflection method revealed low values in all the coatings nearly independent on the annealing temperature.Color variation in the CIE − L ⁎ a ⁎ b ⁎ color space and the reflectance in the UV-visible spectrum range of these niobium oxynitrides were investigated and correlated to their chemical composition and structural features. For both properties, the variation tendencies are quite similar, showing the transition from a nitride-type alloy to an oxide-type one with increasing annealing temperature.

Mechanical and electrochemical properties of Nb2O5, Nb2O5:Cu and graphene layers deposited on titanium alloy (Ti6Al4V)

“…As compared to the results presented in the literature reports, the hardness of investigated Nb 2 O 5 thin film is higher of ca. 50% [30], 53% [31] and 46% [32]. After addition of copper into the Nb 2 O 5 layer, its hardness decreased of about 10% from 8.64 GPa for Nb 2 O 5 to 7.79 GPa for (Nb 0.75 Cu 0.25 )O x layer, but it is still higher than the results presented in the literature reports for pure nioba layer.…”

Thin films and nanostructures of niobium pentoxide: fundamental properties, synthesis methods and applications

“…129,130 So far, sputtering has been the most reported PVD technique to deposit Nb 2 O 5 lms. Generally, Nb 2 O 5 lms can be obtained using direct current (DC) 72,[131][132][133][134][135][136] or radio frequency (RF) 18,132,[137][138][139][140][141][142][143] sputtering techniques with metallic niobium (Nb) 72,131,[133][134][135][138][139][140][141][142][144][145][146] or Nb 2 O 5 (ref. 18, 137 and 143) targets in the presence of carrier gases such as argon (Ar) in oxygen (O 2 ) environments.…”

Amorphous niobium oxide thin films

“…The hardness values ranged between 3.9± 0.1 GPa and 5.3 ± 0.7 GPa. There are few papers that report the hardness of Nb x O y ; Chappe et al [59] mentioned values of about 6 GPa and in a more recent paper Cetinorgu et al [33] measured the hardness of amorphous Nb 2 O 5 films deposited by dual ion beam sputtering as a function of the ion energy and the values ranged between 5.5 and 6.5 GPa.…”