OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 4 2023 heating cycle, as particularly evident in fig. 2, c (CrN mono specimen). However, the relationship between the lattice parameter and temperature within the cycle for the ZrN component of the multilayer coating (fig. 2, b) remains unclear. The intersecting fitted curves within the cycle in this case can be attributed to thermal stresses. Similar dependencies for the substrate material, the WC phase, were not observed, as the lattice parameter changes within the error range during the thermal cycling process. For the substrate, which has a hexagonal symmetry, only the reflection from the (101) plane is investigated for the same reason. The coefficient of thermal expansion (CTE) during thermal cycling is shown in fig. 3. Based on the logic of the thermal cycling process and the existence of extrema in the dependence, the graph in fig. 3 is presented as the absolute value of the ordinate axis. The single-component specimens presented in figs. 3, a, c, d demonstrate a cyclic CTE with good repeatability within the temperature range from 100 °C to 450 °C. For the ZrN mono and CrN mono coating materials, the average CTE is 18×10-6 °C-1. In contrast, for the Fig. 1. Dynamic pattern of the lattice parameter of the components of single-component coatings (a, c), multilayer coatings (b, d) and substrate (e, f) as a function of time (X-ray diffraction numbers). The straight line and the value of the slope of this straight line indicate the general change of the lattice parameter during thermal cycling a b c d e f
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