Influence of the nanostructure of Ti-TiN-(Ti,Al,Cr)N multilayer composite coating on tribological properties and cutting tool life

The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on Their Tribological Properties at Elevated Temperatures

“…The earlier studies [4,34,35] revealed that each nanolayer of the II-a coating had a complex structure, formed due to the planetary rotation of the toolset during the deposition process [4,25,32]. In [4,25], it is also found that the coatings with the nanolayer thicknesses of 70-10 nm also have a similar complex structure. At the same time, the nanolayers of the II-a and II-c coatings affect the formation of the crystalline structure, and the growth of crystals during the deposition is limited by the boundaries of one nanolayer.…”

“…The The results of the studies of the nanolayer coating Ti-TiN-(Ti,Al,Cr)N structure (samples of Group II) are presented in Figure 3 [4].…”

“…Thus, it can be assumed that for the coatings with the minimum value of λ (II-d and II-e), the active oxidation begins at temperatures above 800°C, while for the coatings with larger values of λ (II-a, II-b, and II-c), the oxidation processes start already at a temperature of 700°C. Thus, it can be concluded that a smaller value of λ provides better resistance to thermal oxidation, due to an increased number of interlayer interfaces inhibiting the processes of thermal destruction of the surface layer of the coating [4,11].…”

“…In particular, when the value of λ decreases from 16 nm (II-d) to 10 nm (II-e), the value of f adh increases significantly, and the most significant difference in f adh is demonstrated by the II-d and II-e samples in the temperature range from 800 to 900°C. When the above temperatures are reached, the spinodal decomposition of the (Ti,Al,Cr)N phase begins, accompanied by the formation of a soft hexagonal AlN phase and also a release of pure Ti,Al and Cr [4,11]. The interlayer interfaces can slow down the formation of the decomposition zone, although, if the value of λ is too small, this effect becomes significantly weaker, and as a result, more intense spinodal decomposition is detected for the II-e sample and less intensefor the II-d sample.…”

“…The tribological properties are among the most important mechanical characteristics of the coatings, affecting their performance parameters and working efficiency of products. Due to the fact that the coating characteristics vary noticeably with an increase in temperature and often differ radically from the parameters measured at room temperature [1][2][3][4], the investigation of the tribological properties at temperatures corresponding to the operating temperature (for example, a temperature in the cutting area during the study of the properties of coatings for cutting tools) is essential. The modern trends in improving the coating properties largely imply more complicated architecture and elemental composition [3][4][5][6][7][8].…”