The relationship between substrate temperature and mechanical properties of CrN/Si3N4 nanolayered coatings deposited by magnetron sputtering

The polycrystalline CrN/Si3N4 multilayer films were deposited by magnetron sputtering. We have investigated the effects of substrate temperature on the microstructural, interfacial and mechanical properties. X-ray reflectivity and diffraction (XRR and XRD), and nanoindentation were used to characterize the structures and mechanical properties for the coatings. It was found that the hardness enhancement is caused by the modulus difference in the interface between layer CrN and Si3N4. The elastic modulus is related to the composition of crystalline orientation and distortion. The sharp interface is good for improving the mechanical properties for CrN/Si3N4 multilayer. The variation of hardness and modulus are attributed to the changes in grain size and modulus variation caused by crystalline distortion. Compared to sample at room temperature, the yield stress (resistance to plastic deformation) and fracture toughness (resistance to crack propagation) would be improved by increase of substrate temperature.