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Ab initio study of the properties of Ti1-x-ySixAlyN solid solution
Marques, L.; Carvalho, S.; Vaz, F.; Ramos, Marta M. D.; Rebouta, L.We have studied the electronic, structural, and elastic properties of Ti1-x-ySixAlyN metastable phase, using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, density of states, cohesive energy, formation energy and elastic constants, when Si and Al atoms replace Ti in the TiN lattice. The calculated values of lattice parameters and elastic c...
Structural evolution of Ti-Al-Si-N nanocomposite coating
Carvalho, S.; Rebouta, L.; Ribeiro, E.; Vaz, F.; Tavares, C. J.; Alves, E.; Barradas, N. P.; Rivière, J. P.Ti–Si–Al–N films were prepared by rf reactive magnetron sputtering, in static and rotation modes, using a wide range of different deposition conditions, which created conditions to obtain Ti–Al–Si–N coatings with different structural arrangements. Films prepared below a critical nitrogen flow, under conditions out of thermodynamic equilibrium, revealed a preferential growth of an fcc (Ti,Al,Si)Nx compound with ...
Effect of thermal treatments on the structure of MoNxOy thin films
Cunha, L.; Rebouta, L.; Vaz, F.; Staszuk, M.; Malara, S.; Barbosa, José Gusman; Carvalho, P.; Alves, E.; Le Bourhis, E.; Goudeau, Ph.; Rivière, J. P.Article in Press ; MoNxOy films were deposited on steel substrates by dc reactive magnetron sputtering. The depositions were carried out from a pure molybdenum target, varying the flow rate of reactive gases. X-ray diffraction (XRD) results revealed the occurrence of cubic MoNx and hexagonal (d-MoN) phases for the films with high nitrogen flow rates. The increase of oxygen content induces the decrease of the g...
Effect of the microstructure on the cutting performance of superhard (Ti, Si, A...
Fernandes, C.; Carvalho, S.; Rebouta, L.; Vaz, F.; Denannot, M. F.; Pacaud, J.; Rivière, J. P.; Cavaleiro, A.A d.c. reactive magnetron sputtering technique was used to deposit (Ti,Si,Al)N coatings onto WC–Co cutting tools. The microstructure of the coatings was analysed using X-ray diffraction (XRD) and highresolution transmission electron microscopy (HRTEM) measurement. Before the cutting experiments, the XRD results revealed a structure indexed to an fcc TiN. The results obtained by the XRD tests, with detector vari...
Influence of the O/C ratio in the behaviour of TiCxOy thin films
Fernandes, A. C.; Vaz, F.; Rebouta, L.; Pinto, A.; Alves, E.; Parreira, N. M. G.; Goudeau, Ph.; Bourhis, E. Le; Rivière, J. P.The main purpose of this work consists in the preparation of single layered titanium oxycarbide, TiCxOy, thin films. The obtained results show that the evolution of the different elements concentration with the oxygen flow can be divided into 3 different regimes -- i) carbide, zone I, ii) transition, zone T, and iii) an oxide one, zone II. Structure characterization results showed that the films crystallize in ...
Structural evolution in ZrNxOy thin films as a function of temperature
Cunha, L.; Vaz, F.; Moura, C.; Rebouta, L.; Carvalho, P.; Alves, E.; Cavaleiro, A.; Goudeau, Ph.; Rivière, J. P.Single-layered zirconium oxynitride (ZrNxOy) thin films have been deposited on steel substrates, at a constant temperature of 300 °C, by radiofrequency (rf) reactive magnetron sputtering of a pure Zr target in an argon-oxygen-nitrogen atmosphere. The variation of the flow rate of the reactive gases enabled changes in the composition and structure of the films. X-ray diffraction (XRD) and glancing incidence X-ra...
Properties of MoNxOy thin films as a function of N/O ratio
Barbosa, José Gusman; Cunha, L.; Rebouta, L.; Moura, C.; Vaz, F.; Carvalho, S.; Alves, E.; Le Bourhis, E.; Goudeau, Ph.; Rivière, J. P.The main purpose of this work consists on the preparation of single layered molybdenum oxynitride, MoNxOy. The films were deposited on steel substrates by dc reactive magnetron sputtering. The depositions were carried out from a pure Mo target varying the flow rate of reactive gases, which allowed tune the crystallographic structure between insulating oxides and metallic nitrides and consequently electronic, me...
Structural stability of decorative ZrNxOy thin films
Carvalho, P.; Vaz, F.; Rebouta, L.; Carvalho, S.; Cunha, L.; Goudeau, Ph.; Rivière, J. P.; Alves, E.; Cavaleiro, A.ZrNxOy thin films were prepared by rf reactive magnetron sputtering. The thermal stability of the coatings was tested in vacuum for an annealing time of 1 h in the temperature range 400-800 °C. Residual stresses originated by the deposition process were partially or almost completely released with the annealing, which is consistent with the X-ray diffraction results. Samples with low oxygen fraction (0.10 < ...
Optimization and thermal stability of TiAlN-Mo multilayers
Tavares, C. J.; Vidrago, C.; Rebouta, L.; Le Bourhis, E.; Rivière, J. P.; Denanot, M. F.In this work we focus on the optimization and thermal stability of nanocomposite TiAlN/Mo multilayers that were produced by reactive magnetron sputtering on high-speed steel substrates, with modulation periods below 5 nm. These multilayers were annealed between 600– 900 ºC for 1 h in a vacuum furnace. Preliminary X-ray diffraction results reveal that these coatings are very stable up to 900 ºC, since the multil...
Influence of nitrogen content on the structural, mechanical and electrical prop...
Vaz, F.; Ferreira, J. A.; Ribeiro, E.; Rebouta, L.; Lanceros-Méndez, S.; Mendes, J.; Alves, E.; Goudeau, Ph.; Rivière, J. P.; Ribeiro, António FernandoThis paper reports on the preparation of TiNx thin films by d.c. reactive magnetron sputtering. The coating thickness ranged from 1.7 to 4.2 Am and the nitrogen content varied between 0 and 55 at.%. X-Ray diffraction showed the development of the hexagonal a-Ti phase, with strong [002] orientation for low nitrogen contents, where the N atoms fit into octahedral sites in the Ti lattice as the amount of nitrogen ...
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