Microstructure and mechanical properties of gradient Ti(C, N) and TiN/Ti(C, N) multilayer PVD coatings

Magnetron sputtered homogeneous TiN, gradient Ti(C, N) and TiN/Ti(C, N) multilayer coatings are deposited onto cemented carbide substrates at 350 °C. The microstructure and mechanical properties of the deposited coatings are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), typical secondary ion mass spectroanalyzer (SIMS), nanoindentation, and scratch test. XRD examination indicates that three coatings are of fcc structure. SEM observation indicates that three coatings are characterized by columnar grain structures. The relative concentration of C increases and the concentration of N decreases with increasing gradient Ti(C, N) coating thickness according to SIMS testing. The TiN/Ti(C, N) multilayer coating forms the modulation structure with alternating TiN and Ti(C, N) layers. The gradient Ti(C, N) and TiN/Ti(C, N) multilayer coating exhibit higher nano-hardness compared with homogeneous TiN coating. Gradient Ti(C, N) and TiN/Ti(C, N) multilayer coatings exhibit better adhesion with the substrate compared with homogeneous TiN coating.