This paper reports on the in
vestigation of Ti–Cr–N gradient coatings deposited by cathodic arc
vapor deposition. The Ti–Cr–N coatings were formed by the method of condensation from a plasma phase in a
vacuum with ion bombardment of sample surfaces with combined Ti and Cr plasma flows in a residual nitrogen atmosphere. Auger Electron Spectroscopy (AES) in
vestigations showed that the deposited coatings exhibited compositional gradient: a Cr-rich transition layer was formed during pretreatment of the substrate with Cr ions and a main Ti–Cr–N layer of
varying Ti and Cr composition along the coating thickness was obtained by changing the arc current of Ti and Cr cathodes during deposition. Transmission Electron Microscopy (TEM) obser
vations showed that Ti
xCr
1 − xN solid solutions, with 0.60 < x < 0.84 and 0.25 < x < 0.67 were formed, depending on the relati
ve cathode current change. The grains size of coating was 10 nm.
The biaxial stress, determined from X-ray Diffraction using the sin2ψ method, was compressive and varied from −2.2 to −2.7 GPa for gradient coatings grown on silicon and from −4.1 to −4.3 GPa for the samples grown on carbon steel substrates. Gradient coatings exhibited reduced internal stresses in comparison with coatings of constant composition (−3.9 and −5.6 GPa, for samples grown on Si and steel substrate, respectively). It is established that the mechanical properties (hardness and the modulus of elasticity) of gradient coatings are the superposition of the solid solutions TixCr1 − xN of different concentration (0.60 < x < 0.84 and 0.25 < x < 0.67).