Effect of substrate on wear performance of multilayer hard coating

Both CrN/NbN and CrN coatings have been deposited by physical vapour deposition on a substrate constituted by two different tool steels; the process temperature was lower than the substrate annealing temperature. Tribological performances of the different coatings have been evaluated and compared under the same dry sliding conditions. The results pointed out that CrN/NbN coatings, when deposited on selected substrates, have clearly superior characteristics and well meet the demanding requirements to increase hardness and wear resistance of dies and forging tools. The results highlighted also that coating properties strongly depend on the substrate structure and composition.