Microstructural, mechanical and electrochemical corrosion properties of sputtered titanium-aluminum-nitride films for bio-implants

The effect of aluminum (Al) addition to titanium nitride (TiN) matrix on the structural, mechanical and corrosion resistance properties of titanium-aluminum-nitride was studied. Ti sub(1-x)Al sub(x)N where x = 0, 0.5 and 1 films were coated onto substrates like Si wafer, AISI 316L stainless steel and low carbon steel by a direct current magnetron sputtering process. The layers were sputtered in pure Argon with a substrate temperature maintained at 400 degree C, power of 250 W and a sputtering time of 120 min. XRD, TEM-SAED pattern and XPS analyses were made to study the structural properties of these films. Laser Raman spectrum showed the characteristic peaks at 249 and 659 cm super(-1) for the Ti sub(0.5)Al sub(0.5)N film. AFM analysis showed a relatively smooth surface for the ternary film. Corrosion performance analysis indicated that the Ti sub(0.5)Al sub(0.5)N coated specimen had superior corrosion resistance when compared to TiN and AlN coated substrates. Higher values of nanohardness and lower coefficient of friction were observed for the Ti sub(0.5)Al sub(0.5)N specimen. Blood platelet adhesion experiments were made to examine the interaction between human blood and the materials in vitro.