Produção de filmes DLC-Ag através de técnicas assistidas por plasma

Abstract

Diamond-like carbon (DLC) films have awaked growing interest due to its outstanding mechanical and tribological properties such as high hardness, high wear resistance, chemical inertness, and low friction coefficient. This is unique combination of specific properties enable film application in several fields. However, the high level of compressive stresses, which arise during film growth, hinders to obtain high adhesion. Furthermore, the high film hardness coupled to the difference in thermal expansion coefficient regarding the substrate, results in the DLC does not easily follow the deformation of the substrate. It may result in film delamination and complete failure, especially in case of substrates made of steels. The main objective of this work is to study and develop the deposition process of DLC thin films with inclusion of silver nanoparticles by cathodic cage technology. The adhesion between film and substrate as well as the tribological behavior were analyzed in detail. Doped Diamond-like carbon films with silver (DLC-Ag) were deposited on AISI 301 steel by plasma-enhanced chemical vapor deposition (PECVD). The innovative part of this PhD thesis is the DLC-Ag film deposition by using a silver cathodic cage. Tribologicals tests were performed to evaluate the adhesion between film and substrate, friction coefficient and wear resistance. Raman spectroscopy was applied to verify the structural arrangement of carbon atoms and to obtain important parameters. The films were further characterized by scanning electron microscopy (SEM). The results proved that the deposition by silver cathodic cage is an effective technique for production of more homogeneous DLC-Ag films. The amount of Ag in the film can be adjusted by dwell time of the cathodic cage process.