The influence of deposition conditions and bilayer thickness on physical-mechanical properties of CA-PVD multilayer ZrN/CrN coatings

ZrN/CrN multilayers have been produced by a cathodic arc technique (CA-PVD) using different depositions conditions. Microstructural and mechanical characterizations of the coatings were performed by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM with EDS), transmission electron microscopy (TEM), and Vickers microhardness tests. Variations in thermal transformation properties due to heating within the temperature range from 30 degrees C to 1400 degrees C were studied by differential scanning calorimetry (DSC) measurements. SEM and TEM observations showed that the coatings comprise a multilayered structure with nanometric grains. EDS spectra confirmed the formation of stoichiometric composition. Near-to super stoichiometric nitrides can be suggested in certain specimens. Results of the XRD analysis revealed that the (200) and (111) planes for ZrN and Cr2N are the most intense. Calorimetric tests showed that below a certain annealing temperature no transformations were defined. 1180 degrees C was found to be the value where only one-stage state transformation, presented by endothermic or exothermic reactions, took place. The highest hardness (4685HV0.025) was obtained for the coating with Lambda = 140 nm, P-N = 0.43 Pa, U-s = -70 V.