Radial nanofretting behaviors of ultrathin carbon nitride film on silicon substrate

With a nanoindenter, the radial nanofretting behaviors of amorphous ultrathin carbon nitride (a-CNx) film on the silicon substrate were investigated by a spherical diamond indenter. The experimental results indicate that the radial nanofretting damage on a-CNx film usually successively experiences the buckling, cracking and detachment of film. These damages can be easily detected by the variation in the apparent contact stiffness. Generally, the initial increase in the contact stiffness indicates the buckling of film; the following sharp decrease in the contact stiffness reveals the initiation and propagation of circular cracks in film; the final stable contact stiffness implies the detachment of film.