Effect of Plasma Immersion Ion Implantation (PIII) nitriding on austenitic stainless steel multilayer coatings

Stainless steel coatings are widely used in abrasive and corrosive environments due to their surface properties, and also to their techno-economic impact. Stainless steel coating deposited by Twin-Wire Arc Spray (TWAS) and post-annealed at the vacuum conditions presented very interesting mechanical and corrosion properties, while their tribological behavior, i.e. friction and wear resistance needs further improvement. To enhance those properties, Plasma Immersion Ion Implantation (PIII) technique was used to nitride the coating, afterward, the coatings microstructures were surveyed using Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM). Mechanical properties of the coatings were investigated through nanoindentation tests. The tribological properties were also evaluated. A comparison of the obtained results revealed that the hardness of the nitrided coatings could reach 16 GPa, representing a 50% increase compared to the non-nitrided stainless steel coatings. The friction coefficient showed to be 3 times lower after PIII nitriding. Moreover, the wear rate was reduced by 2 orders of magnitude.