**1.3 Properties of the nanocomposite coatings prepared with single alloying targets**

Since the alloying targets for the nanocomposite coatings are made with amorphous materials, an amorphous phase could easily be formed during the sputtering process, **Figure 3**. According to our previous studies [6, 7], rather to get the nanocomposite structure, the sputtering parameters should be carefully selected, such as a high level of sputtering power, high N2: Ar gas mixing ratio, and a high process temperature. An amorphous coating was easily formed when nonreactive sputtering of an alloying target in an Ar gas atmosphere. On the other hand, when reactive sputtering was performed on the same alloying target in an Ar-N2 mixed gas atmosphere, a nanocomposite nitride phase was formed. The amorphous phase coating shows a higher enough toughness to be used as a buffer layer for the hard coatings [16]. Also, since the amorphous coating shows high corrosion protection with high conductivity, it could be used as the coating for the bipolar plate in the fuel cell [17]. The nanocomposite nitride coatings showed high hardness around 20–30 GPa, and according to the data on the coatings from the various amorphous targets with different metal contents, the hardness of the nitride nanocomposite coatings increased linearly with the decreases in the soft-metal content [6]. The nitride coatings showed very low friction properties even compared with DLC coating in the boundary lubrication conditions of the modified oils. Therefore, it could be used in the various applications of ICE and EV systems.

*Current Development of Automotive Powertrain Components for Low Friction and Wear… DOI: http://dx.doi.org/10.5772/intechopen.106032*

**Figure 3.**

*Summary of the properties of the coatings prepared with the Zr-Cu-Al-Mo alloying targets.*

Erdemir et al. [18] reported that MoN-Cu coatings showed a better friction coefficient in the boundary lubrication area of basic oil and the existence of a Cu matrix could formulate the formation of easy shear tribofilms. In our studies [19, 20], it is also found that low friction and high durable tribofilms were easily formed after wear tests. According to the investigations by RAMAN and XPS, the tribofilms were considered to be amorphous carbon films that must be formed from the decomposition of engine oils by the catalytic effects of the Cu matrix. The more severe the test conditions resulted in the thicker tribofilms [18]. After the engine ring-liner scuffing test of ZrCuSiN, the tribofilms were formed on the surface of the engine ring and the thickness was about 500–700 nm as shown in **Figure 4**. Since the thick tribofilms had high hardness and low friction properties, they could prevent the surface of the engine parts effectively even in severe wear conditions.

The most important result from the studies with the alloying targets is that the composition of the coating layer was almost the same as that of alloying target according to electron-probe microanalysis (EPMA) data on the surface area and glowdischarge optical-emission spectroscopy (GDOES) data throughout the thick coating layer [6]. In particular, for coatings deposited by microcrystalline targets, excellent composition uniformity between the target and the coating is achieved [6, 11]. These

**Figure 4.**

*TEM investigation on the cross-section of tribofilms after engine ring-liner scuffing test [19].*

results suggest that using an alloying target with uniform composition and fine microstructure is a convenient method to reduce process cost and deposit the designed composition.
