**8. Electrochemical properties**

Potentiodynamic polarization curves of the 316l stainless steel (substrate) and deposited film with different Si contents were carried out for studying the Si effect in electrochemical properties of the films. They were tested in 3.5 wt.% NaCl solution, and the results are shown in **Figure 10**. For each curve, corrosion potential (Ecorr) and corrosion current density (Jcorr) were determined and are reported in **Table 7**. The results show that the deposited film with a Si content of 15 at.% has lower Jcorr than that of the uncoated SS 316 L substrate, indicating that with the Si addition or with the coating, the corrosion resistance increases.

Several research groups have found that the addition of silicon to MeN films can improve the corrosion resistance due to the formation of nanocomposite films. The increase on the corrosion resistance could be attributed to the formation of a dense structure, which can block the paths of corrosion medium to the substrate. It has been demonstrated to nanocomposite films, such as: Ti▬Si▬N [102], Al▬Si▬N [103], Nb▬Si▬N [71], and W▬Si▬N and Zr▬Si▬N [104].

**35**

*Effect of Silicon Content in Functional Properties of Thin Films*

**Sample Silicon (at.%) Jcorr (nA/cm2**

The addition of a third element as silicon affects the microstructure and functional properties of the transition metal nitride films, specifically those of zirconium nitride as observed in this chapter. Therefore, it is important has a control of the content of this element in the deposited film to understand and relate the

SS 316l 0 7.13 ±9 −198 ± 94 ZrN 0 3.19 ± 7 −146 ± 69 ZrN + 1Si 8 4.83 ± 4 −155 ± 47 ZrN + 2Si 15 2.28 ± 9 −150 ± 93

*Results from potentiodynamic polarization curves, corrosion current density (Icorr), and corrosion potential* 

**) Ecorr (mV)**

With a silicon content of 8 at.% and with the deposition parameter used, the microstructure changed from a polycrystalline structure of fcc-ZrN (free silicon) to a mixture of nanocrystalline (ZrN) and amorphous (SiNx) phases, and with an increase in the Si content (15 at.%), the films were amorphous. However, these films showed the formation of two crystalline phases corresponding to zirconium nitride and zirconium oxide due to the base pressure used, which is not high enough to remove oxygen in the deposited chamber, and high enthalpy of

These changes in the microstructure and the mixture of phases present in the

• With the addition of silicon, the electrical resistivity increased various orders of magnitude comparison with the resistivity of ZrN. The electrical measurements allowed to determine that the films have a nanocomposite structure: nanocrystalline of ZrN conducting embedded in an amorphous SiNx insulating phases.

• As silicon content increases, the optical response changed from a high reflectance in the infrared region (ZrN) to a high transmittance in the infrared

• The nanohardness values decrease from 29.55 GPa (free silicon) to 15.92 GPa (15.0 at.% Si), due to an increase in the thickness of amorphous phase (SiNx)

• The potentiodynamic polarization curves showed that the coated substrate has higher corrosion resistance than the uncoated substrate due to a decrease in Icorr.

The authors are grateful to Professor Sandra Carvalho of the Minho University (Portugal) who performed the EDS and XPS measurements and the professors Sebastian Calderon and Paulo Ferreira of INL-International Iberian

films generated changes in the functional properties of zirconium nitride:

*DOI: http://dx.doi.org/10.5772/intechopen.85435*

**9. Conclusions**

*(Ecorr) for each sample.*

**Table 7.**

formation for ZrO2.

microstructure and their properties.

region (ZrN▬Si coatings).

**Acknowledgements**

and a decrease in crystalline size (ZrN).

Nanotechnology Laboratory who performed HRTEM.

**Figure 10.** *Potentiodynamic polarization curves for the films and substrate SS 316L.*

*Effect of Silicon Content in Functional Properties of Thin Films DOI: http://dx.doi.org/10.5772/intechopen.85435*


**Table 7.**

*Silicon Materials*

**Table 6.**

boundary sliding [24].

*Results from nanohardness tests.*

**8. Electrochemical properties**

**34**

**Figure 10.**

*Potentiodynamic polarization curves for the films and substrate SS 316L.*

[103], Nb▬Si▬N [71], and W▬Si▬N and Zr▬Si▬N [104].

the SiNx phase thickness is larger than the crystallite size of the ZrN phase, the nanohardness of the films decreases due to an increase of the volume fraction of the amorphous soft phase. The deformation mechanism, in this case, is grain

**Samples Silicon (at.%) Nanohardness (H)**

ZrN 0 29.55 ± 3.70 ZrN + 1Si 8 18.12 ± 2.65 ZrN + 2Si 15 15.92 ± 1.23

**GPa**

Potentiodynamic polarization curves of the 316l stainless steel (substrate) and deposited film with different Si contents were carried out for studying the Si effect in electrochemical properties of the films. They were tested in 3.5 wt.% NaCl solution, and the results are shown in **Figure 10**. For each curve, corrosion potential (Ecorr) and corrosion current density (Jcorr) were determined and are reported in **Table 7**. The results show that the deposited film with a Si content of 15 at.% has lower Jcorr than that of the uncoated SS 316 L substrate, indicating that with the Si addition or with the coating, the corrosion resistance increases. Several research groups have found that the addition of silicon to MeN films can improve the corrosion resistance due to the formation of nanocomposite films. The increase on the corrosion resistance could be attributed to the formation of a dense structure, which can block the paths of corrosion medium to the substrate. It has been demonstrated to nanocomposite films, such as: Ti▬Si▬N [102], Al▬Si▬N

*Results from potentiodynamic polarization curves, corrosion current density (Icorr), and corrosion potential (Ecorr) for each sample.*
