Deposition and characterization of titanium aluminum nitride coatings prepared by RF magnetron sputtering

The aim of this study is to investigate the influence of plasma deposition parameters (the pressure and the substrate bias voltage Vs) on structure, surface morphology, hardness and electrochemical behavior (studied by potentiodynamic polarization and optical microscope (OM) in aggressive environment NaCl 3.5 wt%) of TiAlN coatings. The coatings were deposited by reactive RF magnetron sputtering (13.56 MHz). They were carried out during 60 min and their thickness was approximately 1 μm. Structural analysis shown that TiAlN coating crystallized in cubic (fcc) and hexagonal (hcp) structure with orientations in (1 0 0), (1 1 1), (2 0 0), (1 1 0), (2 2 0) and (3 1 1) planes. The deposited coatings present maximum hardness (H = 25.75 GPa) and Young's modulus (E = 479.82 GPa) at low pressure (20 mTorr) and −60 V of negative substrate bias. Also, mechanical properties (H&E) were strongly influenced by coatings density and grain size. Electrochemical tests revealed that XC48 steel substrate covered with TiAlN coating exhibits excellent corrosion resistance.