| TiN thin films have been serving the industry as the surface of cutting tools and dies, decorative coatings, corrosion resistance coatings, diffusion barriers layers between Cu and Si due to their high hardness, high wear resistance, beautiful color and chemically stability. However, simple TiN films can't fulfil the increasingly industrial applications due to their disadvantages of high temperature antioxidation, diffusion resistance and wear resistance. Therefore, much attention has been paid to multilayered films because of their excellent properties recently. In this paper, TiN, TiN/Ni, TiN/AlN and TiN/AlN/Ni thin film were deposited on Si(100) and AISI 304 substrates with high pure titanium, aluminum and nickel metal targets by reactive magnetron sputtered technique. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS), nanoindentation, scratch tests and electrochemical system were performed to characterize the morphology, phase structure, composition, hardness, Young's modulus, toughness, adhesive strength, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) of the films. And corrosion morphologies were observed by FESEM.The orthogonal test results of TiN films show that the effect of process factors on the hardness of the films is ranked from big to small, that is, temperature > negative bias > electric current > flow of N2. The influence of process factors on adhesive strength between the film/substrate is temperature> flow of N2 > electric current > negative bias. Based on comprehensive consideration of hardness and adhesive strength of the TiN films, an optimization process is obtained, which includes current 0.2 A, negative bias -85 V, N2 flow 4 sccm, substrate temperature 300℃.The effect of negative bias on the TiN film is studied and the results show that the TiN films have a columnar structure. When negative bias voltage increases, a fine, flat, and compact microstructure is developed, and the thickness, hardness, Young's modulus, toughness (H3/E*2) and corrosion resistance of the TiN films all increase first and then decrease with maximum values at -120 negative bias voltages. The structure of the TiN film is facial central cubic, and its preferential orientation strongly depends on the negative bias voltages, it changes from (200) plane to (111) plane, and finally into (220) plane with increasing the negative bias voltage. The effect of substrate temperature on TiN film was investigated, the results show that the film is facial central cubic (fcc)δ-TiN with a preferential orientation depending on the substrate temperature. The preferential orientation of the film is (111) plane when the substrate temperature is between room temperature and 150℃, whereas it changes into (200) plane when the substrate temperature is between 300℃and 450℃. The thickness of TiN film increases when the substrate temperature increases from room temperature to 150℃, however, it almost doesn't change when the substrate temperature continues to be increased. The grain size slightly increases with increasing the substrate temperature. Nanoindentation hardness, modulus and toughness of the films all increase as the substrate temperature increases, and their maximum values are 25.4 GPa, 289.4 GPa and 0.1744, respectively.The influence of depositing time of Ni layer on the structure and properties of TiN/Ni multilayered films was studied, and the experiment results show that the TiN/Ni multilayered films have a obvious layer structure, and the film with Ni layer deposition time of 7 s develops columnar crystals, and the coherent growth takes place between Ni and TiN layers. The columnar structure of the multilayered film disappears with increasing the deposition times of Ni layer. The particle size, the thickness and surface roughness of the multilayered films all gradually increase as the Ni layer deposition times increase. The structure of multilayered films is fccδ-TiN, a preferential orientation of (200) plane is developed, which is independent of the Ni layer deposition times. The results of XPS experiments show that the nickel layer belongs to pure Ni, and the N/Ti atomic ratio in TiN layer is 1.05. Both the hardness and the toughness of TiN/Ni multilayered film have maximum values at Ni layer deposition time of 7 s, and then they both decrease with increasing the Ni layer deposition times. The electrochemical results of TiN/Ni multilayered films are obtained in both 10% H2SO4 and 3.5% NaCl solutions, which show that the corrosion resistance of the TiN/Ni multilayered films with a Ni layer deposited for less than 28 s decreases a little than that of the single TiN film.The experimental results of TiN/AlN nano multilayered films with various AlN layer deposition times show that the surfaces of the multilayered films are very smooth and compact, the peak positions of XRD of multilayered films are very close to that ofδ-TiN, an obvious preferential orientation of (200) plane is found. And the peak positions gradually shift right with increasing the deposition times of AlN layer, showing the lattice constant decreases gradually. The hardness, modulus and toughness of TiN/AlN nano multilayered films all decrease first and then increase with minimum values at 7 s, 9 s and 7 s, respectively, when the AlN layer deposition times increase. The hardness and toughness of the TiN/AlN nano multilayered films are higher than that of single TiN film, and the highest hardness is 34.7 GPa, which is 34 % higher than that of single TiN film (25.9 GPa). Therefore, the super-hard effect is found.The research results of TiN/AlN/Ni nano multilayered films with various AlN layer deposition times show that the surfaces of nano multilayered films gradually become loose and the continuous columnar crystal structure is damaged when the Ni layer deposition times are prolonged. The hardness and modulus of TiN/AlN/Ni nano multilayered films sharply decease with increase in the deposition times of Ni layer. |
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