Micro- and nanocomposite Ti–Al–N/Ni–Cr–B–Si–Fe-based protective coatings: Structure and properties

A new type of nanocomposite Ti–Al–N/Ni–Cr–B–Si–Fe-based coatings 70–90 $\mu$m thick produced by combined magnetron sputtering and a plasma detonation technology is created and studied. Phases Ti$_3$AlN + Ti$_2$Al$_2$N$_2$ and the phases caused by the interaction of plasma with a thick Al$_3$Ti + Ni$_3$Ti coating are detected in the coatings. The TiAlN phase has a grain size of 18–24 nm, and other phases has a grain size of 35–90 nm. The elastic modulus of the Ti–Al–N coating is $E$ = 342 $\pm$ 1 GPa and its average hardness is $H$ = 20.8 $\pm$ 1.8 GPa. The corrosion rate of this coating is very low, 4.8 $\mu$g/year, which is about three orders of magnitude lower than that of stainless steel (substrate). Wear tests performed according to the cylinder-surface scheme demonstrate high wear resistance and high adhesion between the thick and thin coatings.