Comparative study of corrosion and corrosion-wear behavior of TiN and CrN coatings on UNS S17400 stainless steel

摘要

Physical vapor deposition (PVD) multilayered coatings with titanium nitride and chromium nitride top layers were deposited on UNS S17400 alloy in an attempt to improve the corrosion and corrosion-wear resistance of this stainless steel in corrosive environments. The coatings were produced in an industrial chamber by cathodic arc PVD on heat-treated and mechanically polished stainless steel specimens. The microstructures of the substrates and coatings were characterized by X-ray diffraction and scanning electron microscope equipped with an energy-dispersive X-ray spectroscopy system. To evaluate the corrosion and corrosion-wear resistance, reciprocating-sliding tribometer and electrochemical tests were conducted in 3.5% NaCl solution. The results showed that nitride coatings possess, in general, better corrosion and corrosion-wear resistance compared with bare S17400 substrates. Specimens with CrN top coating revealed a typical compact structure and superior corrosion resistance compared with substrate and TiN top coating. However, the sliding motion damaged the surface with some microcracks on the coating, which act as the diffusion channels for NaCl solution; both TiN and CrN top coats experienced approximately similar behavior in corrosion-wear open-circuit potential testing.