**Acknowledgements**

surface layer with new special properties, influencing, among other phenomena, a

The processes that take place in the cutting area are very complex and difficult for modeling. Till present, there is no any ideal model (both mathematical and mechanical), which would take into account all the factors involved in the cutting process (stresses, temperature, diffusion and chemical processes, etc.), and such a model is unlikely to be created in the near future. Accordingly, an entirely adequate assessment of the working efficiency of a coating can be made only in the course of cutting tests. At the same time, there are several techniques, including those considered in this chapter, which make it possible to predict the performance proper-

1.For the coatings under study, the adhesion (molecular) component *fadh* of the coefficient of friction (COF) first grows with an increase in temperature and then begins to decrease noticeably with a further increase in temperature.

2.The temperature at which fadh begins to decrease depends not only on the coating material, but also on the counterbody material. In particular, for AISI 321 steel, the above temperature is 400–450°C, while for AISI 1045 and

3.The samples with the Ti-TiN-(Ti,Cr,Al,Si)N coating showed the smallest value of *fadh* in the temperature range under study (despite the fact that at room temperature, this value differed little from the data of other samples). The smallest change in *fadh* at varying temperature was also detected for the samples with the Ti-TiN-(Ti,Cr,Al,Si)N coating. Meanwhile, the presence of Si in the coating composition does not have a noticeable influence on *fadh*, because the Ti-TiN-(Ti,Al,Cr)N coating demonstrated a result similar to the results obtained

4.The experiments detected the influence of the nanolayer period λ of the Ti-TiN-(Ti,Al,Cr)N coating on its tribological properties. The tests found that for the coatings with all studied values of λ, an increase in temperature first caused

5.Three temperature ranges, characterized by different influence of λ on *fadh*, are detected. In the temperature range of 500–600°C, the influence of λ on *fadh* is insignificant. In the temperature range of 700–800°C, the influence of λ on *fadh* grows noticeably, and there is a gradual increase of *fadh* with a decrease in λ from 302 to 53 nm, then noticeable decrease in *fadh* follows a decrease in λ from 53 to 16 nm, and, again, there is a noticeable increase in fadh with a further decrease in λ from 16 to 10 nm. At temperatures of 900–1000°C, there is an almost continuous decrease in *fadh* with a decrease in λ from 302 to 16 nm, and then a noticeable increase in *fadh* with a further decrease in λ from 16 to 10 nm.

6.Under the simultaneous action of elevated temperature, oxidation processes, and diffusion of Fe from the steel counterbody, a surface layer with new properties is

being formed in the coating, with a positive effect on the decrease in *fadh*.

decrease in the value of fadh is being formed in the coating.

*Tribology in Materials and Manufacturing - Wear, Friction and Lubrication*

ties of the coatings with a fairly high probability. The conducted experiments found the following:

an increase and then a decrease in *fadh*.

**162**

S31600 steels, it stays within a range of 800–850°C.

during the study focused on the Ti-TiN-(Ti,Cr,Al,Si)N coating.

**4. Conclusions**

This study was supported by a grant of the Russian Science Foundation [Agreement No. 18–19–00312 dated 20 April 2018].
