OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 3 2022 (Fig. 1, pos. 9) as shown by arrow (Fig. 1, pos. 10) to provide the residual working pressure. On fi lling the chamber, a gas discharge was ignited at 40 A and bias voltage 700 V with simultaneous preheating the sample to 400°C. The sample’s temperature was controlled using a thermocouple (Fig. 1, pos. 11). A thermal shield (Fig. 1, pos. 12) was mounted to avoid the excess heating of the chamber elements. Ion bombardment cleaning and chemical activation of the sample’s surface was carried out and then an argon and nitrogen (90/10) gas mixture was supplied into the chamber up to reaching the working pressure level. Next step was igniting the 80 A arc discharges on both evaporators (Fig. 1, pos. 13). Each of the evaporators contained a single cathode made of the deposited material (Fig. 1, pos. 14 and 15), i.e. either 99.5% purity Zr or 99.9 % purity Cr. A chamber door (Fig. 1, pos. 16) served for extracting the sample holder and samples after fi nishing the deposition. The table rotation rate was varied during the deposition as follows: 0.5 RPM, 3.5 RPM and 8.0 RPM for samples ZrN/CrN-0.5, ZrN/CrN-3.5 and ZrN/CrN-8, respectively. The resulting sample’s holder rotation rates were then as follows: 20; 140; 320 RPM. The deposited layers were characterized using TEM and synchrotron XRD (Synchrotron Source VEPP-3). TEM allowed characterizing phases formed and inter-layer boundary misorientation. The XRD allowed obtaining the residual stress magnitudes and nitride phase contents. The synchrotron radiation with wavelength 1.540598 Å was used for performing quantitative sin2Ψmethod analysis of residual stresses formed in the multilayer coatings during deposition and cooling. The required for the analysis data on elasticity modulus were obtained from nanoindentation experiments on these multilayer ZrN/CrN-0.5, ZrN/CrN-3.5 and ZrN/CrN-8 coatings and were at the level of 364, 359 and 436 GPa, respectively [16]. The Poisson ratio values for ZrN and CrN were assumed as 0.24 and 0.28, respectively [17, 18]. Results and discussion TEM studies allowed revealing both morphological and orientation differences among the multilayer coatings as depended on the sample’s planetary rotation rates. Fig. 2 shows the bright-fi eld TEM images of the ZrN/CrN-0.5, ZrN/CrN-3.5 and ZrN/CrN-8 multilayer coatings obtained at different rotation rates of the holder. All ZrN/CrN coatings are composed of alternating nitride layers but at least two different layer types can be observed in the ZrN/CrN-0.5 coating. The fi rst one shows formation of nanoscale thickness layers the same as those in the ZrN/CrN-3.5 and ZrN/CrN-8 coatings. The nanoscale layer thicknesses are shown in the TEM images as denoted by the “h” letter). Accelerating both table and holder rotation rate resulted in reducing the nitride layer thicknesses (Fig. 2 d) and it could be suggested from the plot that there is a linear dependence between the holder rotation rate and layer thickness. A regression equation was reconstructed to describe such a dependence that allowed observing the layer thickness tended to zero if the rotation rate approached to the ordinate axis at 592±58 RPM where both nitrides would be homogeneously distributed across the coating. In such a situation it would be plausible formation of either mixed ZrCrN nitride or amorphous layer as discussed below. The second type of layers are submicron thickness ones that are formed at low rate rotations of both table and holder (Fig. 2, a). These submicron layers are composed of the alternating nitride nanoscale ones. The EDS element profi les were obtained on the ZrN/CrN-0.5 coating deposited at the holder rotation rates of 20 RPM (Fig. 3, a). Periodic element concentration dependencies along the line in Fig. 3 a allow suggesting that these submicron layers are of 120±8 nm mean thickness. SAED analysis of phases formed in the coatings showed the presence of both nitrides (Fig. 3). However, there are some specifi c features as those identifi ed from the bright fi eld images (see circles in Fig. 2, a–c). First of all, this relates to crystallite orientations in the layers. Samples of ZrN/CrN-0.5 and ZrN/CrN-3.5 were characterized by the presence of an [111] axis zone common for the ZrN and CrN SAED patterns (Fig. 3 a, b). On the contrary, the SAED pattern from ZrN/CrN-8 sample exposes a common ZrN/CrN axis zone [0-11] as well as extra SAED pattern from the ZrN with different axis zone [1–21]. In other words, there is
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