OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 1 2022 Fig. 6. X-ray diffraction profi les of coatings: CrN (1), ZrN (2), ZrCrN-1 (3), ZrCrN-2 (4), ZrCrN-3 (5), ZrCrN-4 (6) to the WC phase. CrN and ZrN coatings have a pronounced (111) texture, which follows from the magnitude of the refl ections in the diffraction profi les and the almost complete absence of other phase refl ections for these coatings. Multilayer ZrCrN coatings have refl ections of both zirconium nitride and chromium nitride, but ZrN are more intense. The ZrN(220) refl ection is quite broad for ZrCrN-2…ZrCrN-4 samples. The ZrN(111) refl ection is shifted and its intensity is lower. These changes in the diffraction profi les may indicate the nanostructured state of the coating in these samples. The phase composition of ZrCrN-4 coating cannot be effectively assessed as, in addition to the above, there is a signifi cant shift and superposition of many refl ections. The mechanical properties of the coatings were studied by nanoindentation and scratching. Typical loading curves during nanoindentation are shown in Figure 7. The load was selected in such a way that the indentation depth was less than the coating thickness. At the fi rst glance, the plotted curves clearly demonstrate that the mechanical properties of the studied coatings are different. The values of nanohardness and reduced elastic modulus were obtained after data processing by the Oliver–Farr method using specialized software (Table 1). The H/E ratio is often used as a measure of the coating resistance to elastic deformation, with an H/E greater than or equal to 0.1 being considered to indicate high quality of the coating [31]. It follows from the data that only three multilayer coatings meet this characteristic; the chromium nitride coating has the worst properties. The quality of the zirconium nitride coating can also be considered insuffi cient in terms of H/E. It was shown in [26] that a decrease in the thickness of individual layers of multilayer ZrN/CrN coating from 300 to 20 nm allows increasing the hardness of the coating deposited on a 12Cr18Ni10Ti steel substrate from 33 to 42 GPa. The decrease in hardness is also attributed in [26] to the formation of solid solutions of (Zr,Cr)N and (Cr,Zr)N near the (200) refl ection. Such changes in the phase composition were not observed here, but, as in [26], the peaks of the ZrN and CrN refl ections were shifted. This indicates a microdistortion of the crystal lattice, which may be the cause of changes in the mechanical properties of the material. For the case considered in this work, refl ections in XRD profi les taken from ZrCrN coatings are also shifted (Fig. 6). It may also indicate lattice distortion that contributes to hardness enhancement. Similar results of the infl uence of lattice microdistortions on material hardness were earlier observed for austenitic steel produced by electron beam additive manufacturing [32]. The nanoindentation data are in qualitative agreement with the scratch test results. Figure 8 shows CLSM images of scratches on the surface of coatings. The fi rst thing to note is that CrN (Fig. 8a) and ZrN Fig. 7. Nanoindentation loading curves of coatings
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