## 3 Results
Given that the difficulties in measuring the hardness of coatings are associated not only with the possible plastic deformation of the substrate, but also with the noticeable heterogeneity and anisotropy of the properties of the coating itself (the presence of a crystalline and cluster structure, \begin{table}
\begin{tabular}{l c c c} Coating designation & T2 & T7 & T12 \\ Coating thickness, \(\upmu\)m & 0.9–1.5 & 2.0–2.3 & 2.8–3.4 \\  & & & \\ \end{tabular}
\end{table} 
Table 1: Results of coating thickness measurements. Figure 2: Elemental composition of the coatings (the nitrogen content in the coating is \(51.4\pm 2.1\) at.%); the content of the metallic component of the coating is taken as 100 at.% (**a**). Construction of approximating polynomial curves describing the change in the content of elements in the coating (**b**). the possible inclusion of microparticles, including those embedded in the structure and therefore invisible, the presence of dislocations, vacancies and other defects in the crystalline structure, etc.). Therefore, only a large number of measurements with a subsequent rejection of extreme values and statistical processing allows us to obtain a sufficiently adequate hardness value. Results obtained in this way allow for at least a qualitative comparison of the hardness of various coatings with a high degree of reliability, as well as obtaining quantitative results close to real ones. The results of changing the hardness of the coatings show that the T7 coating has the maximum hardness (32.3 \(\pm\) 1.7 GPa) (Figure 3a). This result correlates well with the data [10; 11; 12; 13; 14; 15; 16] showing that the hardness of the (Ti,Al)N coating increases with an increase in the aluminum content to 60-70 at.%, but with a further increase in the Al content, the hardness begins to decrease, which is confirmed by the results of measuring the hardness of the T2 coating (16.7 \(\pm\) 0.8 GPa). The hardness of the T12 coating with a dominant titanium content is 28.5 \(\pm\) 1.1 GPa. The results of the study of fracture resistance in the scratch test correlate sufficiently with the hardness data (Figure 3b). The T7 coating has the best resistance to fracture (complete destruction is not observed under a load of 40 N). The T2 coating has the lowest fracture strength (it breaks under a load of L\({}_{\text{C2}}\) = 14 N). The T12 coating breaks under a load of 28 N.  
Analysis of the scribing groove of the T2 coating (Figure 4) shows the absence of noticeable delaminations from the substrate. Since the coating is quite soft, there is a denting of the coating, accompanied by partial chipping along the boundaries of the groove (Figure 4b-d). The nature of the destruction of the T7 coating during the scratch test differs significantly from that of the T2 coating. The very hard T7 coating is characterized by brittle destruction with the formation of a crack network in the depth of the scribing groove and fragmentary chips at the groove boundary up to 50 \(\upmu\)m wide (Figure 5). Moreover, the complete destruction of the coating does not occur even at the maximum load of 40 N in this test. Despite the presence of areas of delamination in the substrate, these areas are local in nature and do not lead to the complete destruction of the coating. Thus, this coating can be characterized as hard and at the same time quite brittle, which correlates well with the data on (Ti,Al)N coatings with a high aluminum content [37; 38; 39; 40]. The T12 coating is characterized by destruction as a result of extensive delamination (Figure 6a). Along the scribing groove, there is an extended continuous delamination (Figure 6b). The nature of the coating destruction is stepwise (Figure 6c,d), which may be a consequence of the coating structure formed as a result of periodic heating (activation) during the deposition process [41; 42; 43; 44; 45]. Figure 6c shows the location of the lamella cutout. Figure 3: Hardness (**a**) and resistance to destruction in the scratch test of the studied coatings (**b**).