A novel Nb pre-diffusion method for fabricating wear-resistant NbN ceramic gradient coating

Abstract By adopting a novel Nb pre-diffusion process, a wear-resistant NbN gradient ceramic coating was prepared by double glowing plasma alloying technique. The Nb pre-diffusion process, which introduces the defects into the substrate surface, promotes the diffusion of N atoms into the substrate, and thus the diffusive gradient nitride structure is obtained. Besides, the pre-diffusion treated sample exhibits a mixed structure of nano-grains and amorphous areas, which is beneficial for the improvement of mechanical properties. The test results show that the pre-diffusion sample has a good adhesion strength, and it also possesses higher protection capability of the substrate against friction wear than that of co-diffusion sample.