Corrosion performance of TiAlVN-Ag nanocomposite coating deposited by reactive direct current magnetron sputtering

Abstract

Surgical devices and tools are manufactured in AISI 420 martensitic stainless steel, due to its hardenability, adequate hardness and acceptable biocompatibility. Nevertheless, many surface modification strategies are being investigated with a view to improving this material by providing it with self-protection against the colonization of bacteria. One such strategy is the use of a TiAlVN-Ag nanocomposite coating to promote bactericidal effect in surgical devices; however, it is necessary to study the electrochemical response of such coatings to aggressive environments that simulate disinfection and sterilization processes. The aim of this work is to study the relationship between the microstructure, chemical phases and the electrochemical and corrosion response of TiAlVN-Ag coating, varying the amount of silver with the target power increase (0, 50, 70, 80 and 100 W). To study the microstructure, chemical phases, scanning and high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction were used. Roughness, microhardness, residual stresses, qualitative adhesion of coatings were estimated by atomic force microscopy, Knoop indentation, profilometer and Rockwell C indentation, respectively. Electrochemical behavior and corrosion protection of coatings were studied using electrochemical impedance spectroscopy and potentiodynamic polarization. TiAlVN-Ag 50W coating showed an improvement in electrochemical behavior and in protection of the steel against corrosion and exhibiting higher hardness than that of the AISI 420 stainless steel substrates. This coating exhibited a dense microstructure and high crystallinity, indicating that the low Ag content does not affect the insulating nature of the coating matrix.