Effect of target current on microstructure, color and properties of titanium nitride/titanium carbonitride films via mid-frequency magnetron sputtering

In this work, nanocrystalline titanium nitride/titanium carbonitride (TiN/TiCN) thin films were deposited on AISI 316L stainless steel substrates using mid-frequency magnetron sputtering with different target currents from 90 to 135 A. The effect of the target current on the microstructure, color, mechanical and corrosion properties of the TiN/TiCN films were investigated. The L*a* b* color value, hardness (H), strain energy, effective Young's modulus (E*), adhesion and corrosion behavior of the TiN/TiCN films increased as the target current increased from 90 to 120 A, and they dropped as the target current further increase to 135 A. The films became denser and more compact as the target current increased to 120 A. A large number of edge dislocations formed and accumulated near the grain boundaries to create dislocation clusters in TiCN layer and TiN layer. Due to the competition among surface energy, and stopping energy on the surface, the grains mainly grow along the (111) crystallographic plane, the residual stress for the (111) plane were the highest at the target current of 120 A, the maximum H, E* and adhesion of the films were found to be 25.8 GPa, 302.1 GPa and 23.8 N, respectively. The corrosion potential of the film fabricated at the target current of 120 A in 3.5 wt% NaCl solution at 25 degrees C was the noblest (+0.455 VSCE) due to the compact structure.