Investigation of the Deposition Time Effect on the Structural, Morphological, and Mechanical Properties of TiAlN Protective Thin Films

Titanium aluminum nitride (TiAlN) thin films were deposited on glass and stainless steel substrate using a reactive DC magnetron sputtering system, with a mixture of pure nitrogen and argon gases, for different deposition times of 3, 5, and 7 min. The structural properties like phase’s formation and transition, elemental composition, and vibration modes were investigated by X-ray diffraction, energy-dispersive X-ray analysis, and Raman spectroscopy. The morphological properties were analyzed by scanning electron microscopy (SEM). The mechanical and tribological properties in terms of hardness and friction coefficient were determined using the nanoindentation technique and tribometer. It has been found that the films without nitrogen content have a crystalline structure, while the TiAlN films obtained after 3 and 5 min of deposition time exhibit amorphous structures. Films deposited after 7 min of deposition time have TiAlN and oxide phases. The Raman spectroscopy reveals the appearance of TO/LO and 2O modes for all layers and the acoustic modes of second order (2A) for only the TiAl films. SEM images show that the layer thicknesses do not change significantly; however, the film morphology changes with deposition time and becomes denser. The composition of all layers shows an increase of N content and a decrease of Al content, which affect the film mechanical properties. Results from mechanical characterization confirm that the hardness and Young modulus increase with increasing nitrogen content and decreasing Al content, while the friction coefficient significantly decreases.