Microstructures and properties of PVD TiAlN coating deposited on cermets with different Ti(C, N) grain size

In the present work, TiAlN coatings were deposited on Ti(C, N)-based cermet substrates by physical vapor deposition method. Emphasis was focused on the influence of grain size of cermet substrates on the microstructure, growth behavior, mechanical properties, adhesion strength and wear behavior of the coatings. The results show that finer Ti(C, N) grain size leads to higher nucleation density and lower growth rate of coatings, indicating the crystallite size of the TiAlN coatings decreases with decreasing Ti(C, N) grain size. Nanoindentation tests show that the coatings deposited on cermets of the finest grain size exhibit the highest hardness (H), elastic modulus (E), H/E and H-3/E-2 of 34.5 GPa, 433.2 GPa, 0.080 and 0.22, respectively. The adhesion strength between coating and substrate is also enhanced with decreasing Ti(C, N) grain size by scratch test, which corresponds to the grain size and H/E and H-3/E-2 of the coating. Besides, the lower surface roughness and better mechanical properties of the coating deposited on finer grained cermet contribute to the better wear resistance of the coating.