| Abstrakt: |
Comparative investigations of the structural characteristics and functional properties of Ti–Al–Mo–N and Ti–Al–Mo–Ni–N coatings fabricated by the ion-plasma-vacuum-arc deposition (arc-PVD) method are performed to study the influence of nanostructuring nickel additives. Coatings have a multilayered architecture with alternating layers of titanium and molybdenum nitrides. The molybdenum concentration is about 22 at % and that of nickel is 7 at %, which corresponds to optimal amounts for the best strength and tribological properties. It is shown that, when introducing nickel, the coating modulation period decreases from 60 to 30 nm with a simultaneous increase in hardness from 37 to 45 GPa. Herewith, the fracture toughness of coatings, which was judged from the relative work of plastic deformation and parameter H/E and H3/E2, increases. Ductile nickel added to the structure of the hard nitride coating promotes a decrease in the level of compressing macrostresses in the material from –2.25 to –0.58 GPa, which, however, does not lead to a decrease in hardness and wear resistance, as is shown by scratch tests. It is concluded that the factor determining the physicomechanical characteristics of the coating is the refinement of the grain structure of the material rather than the macrostress level. The introduction of nickel positively affects the heat resistance of the coating, which successfully protects the substrate material against the oxidation at temperatures up to 700°C, which can be conditioned by the probability of the formation of Ni-containing oxides NiMoO4 and NiTiO3 on the surface. Herewith, their appearance, fracture, and effect as abrasive particles can be the reason for the variation in the wear mechanism under friction at high temperatures. [ABSTRACT FROM AUTHOR] |
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