**2.3 Characterization of the coatings**

**Unit Traget power (Kw) Bias (V) Temper (°C) Rotation velocity (rpm) Time (mn) Ar Gas flow N2 SCCM C2H2** TiAl 6 −300 250 0.7 22 400 – – TiAlN 7.5 −200 150 0.6 17 770– 800 90–150 – 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

The multilayer coatings prepared in this work and their mechanical properties are shown in **Table 2**.

**Table 1.** *Deposition conditions.*


#### **Table 2.**

*Mechanical properties of coating layer and substrate.*

The fretting wear behavior of multilayer TiAlCN/TiAlN/TiAl has been carried out in previous studies [3]. Indeed, a special focus in this chapter was given to the characterization and the study of the behavior of fretting wear coating of multilayer TiAlZrN/TiAlN/TiAl. The total thickness of the coating is determined by the electronic scanning microscope (SEM) after a major fracture in vertical section, followed an analysis of the chemical composition by energy dispersive spectroscopy (EDS). The morphology of the coating TiAlZrN is being reviewed by an atomic force microscope (AFM). The microstructural characterization of this coating is investigated by X-ray diffraction (Philips X'pert system). Scans were carried out in the grazing angle mode with an incident beam angle of 3° and the normal θ-2θ method classically used in the same situation. Young's modulus and hardness were measured by nanoindentation tests with a nanoindenter MTS-XP. The indentation was performed using a triangular Berkovich diamond pyramid. SEM and AFM observations allowed determination of the global coating thickness and the morphology of the surface, respectively. The multilayered TiAlZrN/TiAlN/TiAl coatings had a mean thickness of 800 nm, distributed in three layers as shown in **Figure 1**. The surface was globally uniform with some domes and tiny craters spread all over the area **Figure 2**.

Dimensional measurements showed that the domes had a mean diameter of about 25 nm and the craters a maximum depth of 16 nm. The crystallographic structure and orientation of the coatings were determined by X-ray diffraction. Phase identification for multilayer coatings TiAlZrN/TiAlN/TiAl revealed the presence of reflection peaks corresponding to stripes (100) and exhibited a weak intensity peak at 2θ = 2.83° (44.74 Å) (**Figure 3**). It can be seen that the as-coated state already has a crystalline structure of AlZr3. The presence of crystallographic structure is linked to the columnar morphology of the layers observed by SEM on a cross section **Figure 4**. The chemical composition of multilayered coatings is shown in **Figure 5**. The measurements of nanoindentation carried out on a depth exceeding the thickness of the coating made it possible to determine the average hardness and average Young modulus in this multilayer TiAlZrN/TiAlN/TiAl. The results are presented in **Table 2**.

**Figure 1.**

*Distribution and thickness of the layers in the multilayers coating: (a) TiAlZrN/TiAlN/TiAl and (b)TiAlCN/ TiAlN/TiAl.*

**321**

**2.4 Fretting tests**

**Figure 3.**

**Figure 2.**

machine (MTS).

Fretting wear, which is considered a nuisance in several branches of industry such as aeronautics, nuclear industry, etc., refers to the degradation of the contact surface resulting from wear, which requires an overhaul or replacement of the machine components. It is defined as the wear that takes place during a low amplitude oscillatory movement between two apparently immobile solids under a load normal to the contact surface. Such a phenomenon is observed especially in assemblies subjected to vibrations. To simulate the industrial process, a test bench was developed within the laboratory and subsequently installed on a fatigue

The fretting tests were carried out on an MTS tension compression hydraulic machine. A sphere-on plane configuration was employed as shown in **Figure 6(a)**. The counter-body was a polycrystalline alumina ball with 24 mm diameter, a Young's modulus of 310 GPa, and a hardness of 2300 Hv0.05. The flat coating alloy (10 mm × 10 mm × 12 mm) specimens were manufactured from a cast bar of

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

*AFM morphologies of the surface layer of TiAlZrN.*

*XRD diffractogram of the TiAlZrN/TiAlN/TiAl multilayer.*

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

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

TiAlCN/TiAlN/TiAl [3] 15 260 TiAlZrN/TiAlN/TiAl 28 310 AISI4140 steel 42 210

The fretting wear behavior of multilayer TiAlCN/TiAlN/TiAl has been carried out in previous studies [3]. Indeed, a special focus in this chapter was given to the characterization and the study of the behavior of fretting wear coating of multilayer TiAlZrN/TiAlN/TiAl. The total thickness of the coating is determined by the electronic scanning microscope (SEM) after a major fracture in vertical section, followed an analysis of the chemical composition by energy dispersive spectroscopy (EDS). The morphology of the coating TiAlZrN is being reviewed by an atomic force microscope (AFM). The microstructural characterization of this coating is investigated by X-ray diffraction (Philips X'pert system). Scans were carried out in the grazing angle mode with an incident beam angle of 3° and the normal θ-2θ method classically used in the same situation. Young's modulus and hardness were measured by nanoindentation tests with a nanoindenter MTS-XP. The indentation was performed using a triangular Berkovich diamond pyramid. SEM and AFM observations allowed determination of the global coating thickness and the morphology of the surface, respectively. The multilayered TiAlZrN/TiAlN/TiAl coatings had a mean thickness of 800 nm, distributed in three layers as shown in **Figure 1**. The surface was globally uniform with some domes and tiny craters spread

**Hardness (GPa) Young's modulus (GPa)**

Dimensional measurements showed that the domes had a mean diameter of about 25 nm and the craters a maximum depth of 16 nm. The crystallographic structure and orientation of the coatings were determined by X-ray diffraction. Phase identification for multilayer coatings TiAlZrN/TiAlN/TiAl revealed the presence of reflection peaks corresponding to stripes (100) and exhibited a weak intensity peak at 2θ = 2.83° (44.74 Å) (**Figure 3**). It can be seen that the as-coated state already has a crystalline structure of AlZr3. The presence of crystallographic structure is linked to the columnar morphology of the layers observed by SEM on a cross section **Figure 4**. The chemical composition of multilayered coatings is shown in **Figure 5**. The measurements of nanoindentation carried out on a depth exceeding the thickness of the coating made it possible to determine the average hardness and average Young modulus in this multilayer TiAlZrN/TiAlN/TiAl. The results are

*Distribution and thickness of the layers in the multilayers coating: (a) TiAlZrN/TiAlN/TiAl and (b)TiAlCN/*

**320**

**Figure 1.**

*TiAlN/TiAl.*

all over the area **Figure 2**.

**Table 2.**

*Mechanical properties of coating layer and substrate.*

presented in **Table 2**.

**Figure 2.** *AFM morphologies of the surface layer of TiAlZrN.*

**Figure 3.** *XRD diffractogram of the TiAlZrN/TiAlN/TiAl multilayer.*
