**1. Introduction**

The hard coatings have been used extensively to increase the wear resistance under loading conditions in fretting wear. Various methods of coating deposition have found industrial application. One successful approach is the physical vapor deposition (PVD) technique. Presently, development of TiAlN-based multilayer and nanocomposite coatings are the most important trends in the hard coating industry [1]. The ternary coating has better resistance to oxidation and poor adherence [2]. In order to remedy these imperfections, additional constituents such as carbon or zirconium are recommended. In order to characterize the quality of a coating, evaluation of a number of properties is essential. Hardness, friction coefficient, roughness, wears, and oxidation resistance have primary importance. The addition of carbon to TiAlN provides a quaternary coating, TiAlCN, which has better resistance to oxidation, improved mechanical properties, and has good adherence with high tribological capacities [3, 4]. However, the addition of zirconium to TiAlN provides a quaternary coating, TiAlZrN. Although some studies are available on TiAlZrN layers and their behavior in terms of wear [2], data on resistance to fretting wear are not available. First, according to the intensity of the imposed

parameters (normal force, amplitude of displacement, and frequency), fretting maps were established to determine the sliding conditions and the type of damage according to the fretting conditions. The running condition fretting maps indicate when total or partial sliding conditions occur, and the material response fretting maps quantify the damages (wear, cracking). Actually, the partial slip regime (PSR) is associated with cracking as a result of a fatigue phenomenon, whereas the gross slip regime (GSR) leads to wear by debris formation [5]. The mechanical models of contact including elastoplasticity are used to delimit the boundary between the partial slip and gross slip [6]. Crack propagation is studied using efficient fatigue criteria [7, 8], while wear is studied by more or less empirical multiple quantitative approaches [9]. Second, in this step, we have to determine the tribological properties of quaternary coatings and correlate the worn volume according to the parameters of loading in fretting wear. Finally, the comprehension of fretting behavior remains sensitive as soon as the mechanical, thermal, and physical-chemical interactions [occurring in a contact associated with the role played by the interfacial layer generated by detachment of the particles during friction (third body)] need to be taken into account; when wear particles have been liberated from the surface, some of them may attach to the counterface to form a transfer layer and significantly change the tribological properties of the counterface (like forming a new counterface) [10–13]. The wear analysis performed with imposed displacements or tangential forces is based on an energetic approach [6, 14]. The wear volume increases linearly with the dissipated energy within the contact.

The PVD surface treatment process makes it possible to produce nanocomposite coatings with a metal matrix. During this process, the particles are accelerated at very high speed through a flow of inert propellant gas under pressure and are preheated to a temperature below the melting temperature of the materials to be sprayed [1–3]. Due to the very high speeds, the coatings thus formed are very dense [2]. Obtaining large thicknesses (several micrometers), accompanied or not by superficial oxidation, with densities close to the volume of base substrate have advantages over deposits produced by other thermal processes. The cold spraying process is also a repair method used either on new parts under development or on parts under maintenance. Certain layers are also a means of protection against corrosion, for example, for components of aeronautical parts. Reinforcement phases can be filled layers, the composition of which also varies depending on the material of the matrix [2, 4]. Solid lubricants can also be incorporated [5]. Coatings with solid lubricants are used for technical parts such as bearings or rings to reduce friction.

The tribological circuit in general describes the different flow rates of the third body capable of being activated in an elementary contact in two dimensions [6, 7]. The internal source flow corresponds to the detachment of particles, due to surface tribological transformations (TTSs) [8, 9], cracking, and adhesion. It leads to the formation of the third natural body. The external source flow comes from the introduction of a third artificial body into the contact. The internal flow is the flow of the third body which circulates between the first bodies. The external flow is the flow of the third body which escapes from the contact. It is divided into a recirculation flow and a wear flow. The recirculation flow consists of the third body which, when reintroduced into contact, driven for example by one of the first bodies, will again contribute to speed accommodation. On the other hand, the wear flow is made up of the third body which, when definitively ejected from contact, will never again participate in speed accommodation. The debits will be estimated on a relative qualitative scale from very low (\*) to very high (\*\*\*\*\*\*).

The rheology of the third solid body is characterized relatively on the basis of its cohesion and its ductility [7]. These two properties are determined from the morphology and texture of the third body obtained by observations and analyses after

**319**

**Table 1.**

*Deposition conditions.*

*Fretting Wear Performance of PVD Thin Films DOI: http://dx.doi.org/10.5772/intechopen.93460*

eters in the fretting wear is presented.

420 HV0.05, with surfaces of (10 × 10) mm2

**2. Experimental procedures**

to eliminate all these antagonists.

are shown in **Table 2**.

**Unit Traget** 

**power (Kw)**

**Bias (V)**

**Temper (°C)**

TiAlN 7.5 −200 150 0.6 17 770–

**2.3 Characterization of the coatings**

**2.1 Substrate**

cleaner.

**2.2 Deposition**

tests. The cohesion translates a third body more or less compacted or pulverulent.

In this chapter, the multilayer coatings' behavior under various loading param-

Specimens used in this work were machined from steel trade AISI4140 hardness

were divided into two sets; the first set was coated by TiAlCN/TiAlN/TiAl and the second round by TiAlZrN/TiAlN/TiAl. Before PVD treatment, all samples were cleaned and polished with trichloroethylene, acetone, and alcohol in an ultrasonic

The multilayer coatings were deposited on the steel AISI4140 by the process of spraying DC magnetron mode, using target compounds TiAl (50°/°Ti, 50°/°Al) [3] and Al-Ti-Zr (19°/°Ti, 21°/° to Al, 10°/°Zr, 50°/°N) of high purity (99.9999%).

The samples were mounted on a continued rotating satellite inside the vacuum plasma chamber. The atmosphere was chosen to produce successively under a layer of TiAl, a buffer layer of TiAlN, and then a layer of TiAlCN or TiAlZrN. Indeed, the thin films of TiAl and TiAlN aim to improve the adhesion layers TiAlCN [2, 3] and TiAlZrN [10] with steel. The optimum conditions for filing as the bias voltage targets, temperature, and time of deposition were determined and optimized in previous studies; **Table 1** shows in detail the optimal conditions for verification. In addition, Argon, acetylene, and nitrogen gas which are of very high purity (99.999%) were introduced into the vacuum chamber. The basic pressure in the room was 5.10−5 Pa, which grew to 0.1 Pa for the deposition of desired layers. The distance between the target and the substrate surface was 35 mm. Before the deposition, the surface of the substrate was cleaned by argon ion bombardment at the end

The multilayer coatings prepared in this work and their mechanical properties

**Rotation velocity (rpm)**

TiAl 6 −300 250 0.7 22 400 – –

TiAlCN 7.5 −200 100 0.6 42 950 150–135 20–135 TiAlZrN 7.5 −200 100 0.6 42 950 150–135 20–135

**Time (mn)**

**Ar Gas flow N2 SCCM**

800

**C2H2**

90–150 –

and (10 × 12) mm<sup>2</sup>

. These samples

Ductility reflects the ease with which the third body spreads in contact.

tests. The cohesion translates a third body more or less compacted or pulverulent. Ductility reflects the ease with which the third body spreads in contact.

In this chapter, the multilayer coatings' behavior under various loading parameters in the fretting wear is presented.
