Effect of Ag content on the microstructure, tribological and corrosion properties of amorphous carbon coatings on 316L SS

The mechanical durability and stability of a-C:Ag nanocomposite coatings deposited on 316L stainless steel substrates were investigated with respect to Ag content. The coatings were prepared using graphite and Ag targets. The coatings were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). XPS and Raman spectroscopy confirmed the formation of sp2 clusters in the a-C coating with 4.46 at.% Ag content. Surface roughness was found to be reduced by increasing the Ag content in a-C coatings as confirmed by AFM analysis. TEM analysis also showed the presence of nanostructured Ag in the a-C matrix. The tribological and corrosion properties of these coatings were also investigated. Hardness and Young's modulus were found to decrease with increase in Ag content. The experimental results revealed that the friction coefficient could be significantly reduced due to inclusion of Ag in the composite coating. In particular, the coating with an Ag content of 4.46 at.% showed the best tribological behavior. Inclusion of Ag also improved the corrosion resistance of the composite coating. It was concluded that Ag content in a-C:Ag nanocomposite coating has a significant effect on the tribological and corrosion properties of the coating. Experimental results revealed that optimum Ag content (4.46 at.%) in a-C:Ag nanocomposite coatings may be effectively utilized to protect 316L stainless steel substrates.