Relationship between structure, surface topography and tribo-mechanical behavior of Ti-N thin films elaborated at different N2 flow rates

Titanium nitride films were deposited by reactive magnetron sputtering on Si (100) wafers, glass and Ti6Al4V substrates. The film deposition was carried out in a gas mixture of Ar and N2. The nitrogen content was varied between 0 and 30 % of the total gas mixture. This variation led to the formation of different films with different microstructures. The microstructure of the Ti-N coatings presented nanocomposites with a low tendency to surface oxidation. From a pure Ti to tetragonal Ti2N and cubic Ti-N microstructures, the films showed a (111) TiN plane growth that led to an increase in the lattice strain and a decrease in the grain size when increasing the nitrogen flow rate. The water-film contact angle measurements showed that the surface hydrophobicity increased with the increase of nitrogen content in the film. Mechanical properties were measured and a strong dependence between microstructure and hardness was found. The Ti-N deposited under 20 % of N2 exhibited the highest hardness, the best adhesion and wear resistance, and the lowest friction coefficient with the presence of (111) fiber texture.