**1. Introduction**

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 [1–4], 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 [3–8].

Coatings are being developed with a nanolayer architecture, characterized by a number of significant advantages compared to traditional monolithic coatings [3, 6–8]. In particular, the studies detect improved crack and impact resistance of the coatings with a nanolayer architecture [9–13]. The influence of a nanolayer structure of the coating on its tribological properties is of great importance. The studies have found that the coatings with a nanolayer structure are characterized by a reduced COF, high hardness, and a low level of residual stresses [6], while with a decrease in a thickness of the binary nanolayer λ, the COF decreases and the wear resistance increases [8]. The investigation has also demonstrated that a decrease in the nanolayer period λ leads to an increase in hardness, a decrease in the COF, and an improvement in the resistance to the failure of cohesive bonds between nanolayers [14–17]. In particular, in [15], the studies of the TiAlCN/VCN nanostructured coating with λ = 2.2 nm have found that for this coating, the COF grows with an increase in temperature up to 200°C, but begins to decrease at temperatures above 650°C. The experiments found a decrease in the COF for the CrAlYN/CrN nanolayer coating with λ = 4.2 nm with an increase in temperature up to 650°C [16]. The study of the Ti/TiAlN/TiAlCN nanolayer coating detected its low COF and high wear resistance [17]. The tribological properties of the TiAlN/CNx nanostructured coating with λ = 7 nm were considered in [18]. The tests have found that the TiAlN/CNx nanostructured coating is characterized by small grain sizes and lower surface roughness in comparison with a monolithic coating of a similar composition and also by a lower COF and higher wear resistance.

**2. Experimental**

**2.1 Coating deposition**

*DOI: http://dx.doi.org/10.5772/intechopen.93973*

(Zr,Al,Si)N coating.

frequency n (see **Table 1**).

mentioned reasons are as follows:

surfaces.

**Table 1.**

**153**

Coatings were deposited through the filtered cathodic vacuum arc deposition (FCVAD) [5, 7, 25–29] technology. The experiments were carried out using a unit VIT-2, (IDTI RAS – MSTU STANKIN, Russia) with two arc evaporators with a pulsed magnetic field and one arc evaporator with filtering the vapor-ion flow. Furthermore, the complex also included a source of pulsed bias voltage supply to a substrate, a dynamic gas mixing system for reaction gases, a system to control automatically the chamber pressure and a process temperature control system, and

*The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on…*

Group I included samples with three coatings of various compositions, i.e. I-a – Ti-TiN-(Ti,Cr,Al,Si)N coating; I-b – Zr-ZrN-(Nb,Zr,Cr,Al)N coating; I-c – Zr-ZrN-

Group II included samples with the Ti-TiN-(Ti,Al,Cr)N coatings with different values of the nanolayer period λ, formed through varying the turntable rotation

During the friction process, a complex system is formed in the actual contact areas. This system possesses a number of specific properties which differ from the properties of the contacting body materials when considered separately, without contact during friction. Apparently, to obtain reliable data correlating with the main factors of friction and wear, it is necessary to assess the properties of the contact area directly. However, there are several reasons which make it difficult to measure the tribological parameters directly during the operation of actual products at elevated temperature of the contact forces. Some specific features of the above-

• forces and temperatures on the contact area are distributed unevenly,

• there is a difficulty in determining the actual contact loads due to the

differences in chemical purity and discreteness of contact of the contacting

It should be noted that while two surfaces are sliding, the tangential contact force is being affected not only by shear strength of adhesive bonds, but also the deformation component of the friction force [30]. The contacting surfaces (especially those subject to wear) can have significant roughness and be heterogeneous in their physical and mechanical properties due to the polycrystalline structure. Thus, the deformation component of the tangential contact force can have a significant influence on the tribological properties of products, but its direct determination in

**Sample II-a II-b II-c II-d II-e** Turntable rotation frequency *n*, min�<sup>1</sup> 0.25 1 1.5 5 7 Nanolayer period λ, nm 302 70 53 16 10

a system for stepless adjustment of planetary gear rotation.

Two groups of samples were manufactured:

**2.2 Measurement of tribological parameters**

*The samples depending on the turntable rotation frequency.*

The influence of the elemental composition of the coatings on their tribological properties was also investigated. The experiments revealed the COF value at room temperature for the coatings of TiN (0.55), TiCN (0.40), TiAlN (0.50), AlTiN (0.7), as well as AlTiN/Si3N4 consisting of AlTiN nanoparticles embedded into amorphous Si3N4 matrix (0.45) [19]. During the studies focused on the TiAlCrN/ TiAlYN and TiAlN/VN coatings, Hovsepian et al. [20] found that the introduction of Y in the coating composition led to a decrease in the COF from 0.9 up to 0.65 during the tests conducted at temperatures ranging from 850 to 950°C. For the TiAlCrN coating, the COF was 1.1–1.6 (at temperatures of 600–900°C), while for the TiAlN/VN coating, the COF was 0.5 (at 700°C). Mo et al. [21] found that the COF of the AlCrN and TiAlN coatings was 0.75 and 0.85, respectively. With an increase in the Cr content in the CrAlN coating, a slight increase in the COF was detected [22]. Nohava et al. [23] studied the properties of the AlCrN, AlCrON, and α-(Al,Cr)2O3 coatings in comparison with the properties of the TiN-AlTiN reference coating at temperatures of 24, 600, and 800°C. The maximum value of the COF was detected at a temperature of 600°C for all the studied samples, while at a temperature of 800°C, there was a significant decrease in the COF (to 0.6–0.8) to the values lower than those detected at a room temperature (0.3–0.5). Bao et al. [24] found that for the TiCN/TiC/TiN coating, the COF was 0.4–0.5 at a room temperature and 0.6–0.7 – at a temperature of 550°C.

Thus, it can be asserted that:


*The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on… DOI: http://dx.doi.org/10.5772/intechopen.93973*
