Effect of nano-multilayered ZrN/TiAlN hard coating as the interlayer on the microstructure, mechanical properties, and wear resistance

Abstract

A nano-multilayered ZrN/TiAlN was deposited as the interlayer to enhance the coating hardness and wear resistance between the inner TiAlN and outer ZrN layers. The structural evolution and mechanical performance of the multilayer coatings were significantly achieved. High-resolution transmission electron microscopy (HRTEM) revealed a local epitaxial growth between the nano multilayers, in which (111) crystal planes for TiAlN was parallel to (111) crystal planes for ZrN. Nanoindentation experiments were conducted to evaluate the mechanical properties. TiAlN-ZrN/TiAlN-ZrN and ZrN-TiAlN-ZrN/TiAlN-ZrN featuring a multilayered architecture, exhibited the higher hardness values of 24.68 ± 3.27 GPa and 25.34 ± 3.42 GPa respectively. Additionally, The wear mechanism for coatings under a load of 10N was dominated by abrasive wear, whereas that under a load of 15N was mainly oxidation wear and abrasive wear. Furthermore, in comparison to TiAlN-ZrN, the wear tracks on TiAlN-ZrN/TiAlN-ZrN exhibited a lower width value about 423 μm, indicating a better wear resistance. This enhancement could attribute to the alternating stress fields hindering the dislocation movement, which arose from coherency strains due to a mismatch in the lattice differences between nano multilayers. Simultaneously, the interface of nano layers inhibited oxygen diffusion, enhanced the antioxidant effects and further improved the wear behavior.