OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 2 2023 In chamber 1, substrates made of 92 wt.% Co-8 wt.%WC alloy for the deposition of multilayer coatings are attached to a rotating holder 2, installed on a rotating table 3. A turbomolecular pump 4 creates a vacuum in chamber 1, and after reaching a vacuum of 10-4 Pa, inert filling gas puffing occurs through a plasma source 5 to create the required working pressure in the chamber. When the gas discharge is ignited with a current of 40 A and a bias voltage of 700 V is applied to the substrate holder with the specimens, the substrates are heated to 400 °C. After cleaning the surface of the objects under investigation by ion bombardment and its chemical activation, a mixture of nitrogen and argon gases (90/10) puffing occurs to the desired pressure, and the arc evaporator discharges are ignited with a current of 80 A for each of it. One cathode made of the deposited material (positions 6 and 7) was installed in each evaporator, in our case these were Cr (99.9%) and Zr (99.5%). Specimens with multilayer coatings were circular in shape, 15 mm in diameter, and 3 mm thick, with a thickness of coatings. The thickness of the coatings was in all cases 5 μm. The most appropriate method for the research task is in-situ synchrotron characterization of multilayer coatings during temperature exposure to a multilayer coating deposited on a substrate. Coatings applied to the 92 wt.% Co-8 wt.% WC alloy substrate were investigated using X-ray diffraction analysis (XRD) with synchrotron radiation (work was carried out at VEPP-3 synchrotron). The wavelength during synchrotron experiments was 1.54 Å. For in-situ studies, the sample with a multilayer coating was placed on a heated holder in an air atmosphere. Then the initial XRD pattern was obtained using an asymmetric measurement method, i.e., with a fixed angle of incidence of radiation in the range of angles 2Θ, selected depending on the material of the multilayer coating (31–48). In the next stage, the sample was heated at a given rate, providing exposure time sufficient for step-by-step construction of the XRD pattern of the sample with the multilayer coating using synchrotron radiation. The temperature range of heating was determined by the real operating conditions of the coatings. Simultaneous registration and recording of XRD patterns with a step ensuring sufficient accuracy of identification the phase transitions and structural changes occurring during heating of the coating in the temperature range from 50 to 750 °C was made. To ensure the necessary measurement accuracy, a part of the 2Θ angle range was registered, in which one reflection of each phase of the multilayer coating was presented. The sample with the multilayer coating was heated in the temperature range from 30 °C to 750 °C with a temperature increase rate not exceeding 5 °C/min, providing exposure time sufficient for the construction of the XRD pattern of the sample, and with a step of 10 °C, XRD patterns were registered and recorded using synchrotron radiation in the X-ray range of radiation with a scanning step of 0.05 degrees and a range of angular position scanning of 2Θ from 31 to 48 degrees. After obtaining the necessary number of X-ray diffraction patterns at different temperatures, the obtained profiles were approximated with the determination of such characteristics of the reflections of the present phases as interplanar spacings (d), the full width at half maximum intensity (FWHM) and identification of all phases in the multilayer coating within the diffraction patterns selected from the entire array of obtained patterns after visual assessment of the temperature at the phase transformations beginning. To obtain the characteristics of the reflections presented in the coating phases, the obtained X-ray diffraction profiles were approximated by the Pseudo-Voigt function [19]. After determining all the necessary parameters of the diffraction pattern profile, the lattice parameter (a) was calculated for the cubic symmetry of the CrN and ZrN phases presented in the multilayer coating, as Fig. 1. Multilayer nanostructured ZrN/CrN coating application unit scheme
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