Fabrication and performance of TiN/TiAlN nanometer modulated coatings

TiN/TiAlN multilayered coatings with bilayer periods (λBD) ranging from 6 to 30 nm were prepared on TC4 alloy and Si (100) wafer substrates by magnetic filtered pulsed vacuum cathodic arc plasma technique. The analyses with scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscope (EDS) and X-ray photoelectron spectroscope (XPS) with Ar + sputtering indicated that the as-deposited coatings had nanometer modulated structure, TiN and TiAlN with (111) preferred orientation were the main compounds and the average atoms ratio of N:(Ti + Al) was about 1.24–1.29. Scratch test showed that the coatings were fairly adherent to TC4 substrates, and the maximal critical load was about 57 N. The highest nano-hardness and modulus about 28 GPa and 283 GPa, respectively, were obtained for the multilayer with λBD = 12 nm, examined with nano-indentation method. The electrochemical corrosion test showed that the coatings improved the TC4 alloy's property of anti-corrosion effectively, especially with λBD = 20 nm.