Influence of β-SiC phase contents on hardness and elastic modulus of multilayered diamond/β-SiC composite coatings

Abstract

Multilayered diamond/β-SiC composite coatings exhibit excellent mechanical properties, and the content of β-SiC phase plays a crucial role in determining the mechanical properties. In this work, a periodic structure of four-layer multilayered diamond/β-SiC composite coatings with different β-SiC phase contents were deposited on WC-Co substrates. The results demonstrate that the multilayered diamond/β-SiC composites with different β-SiC phase contents form a well-defined periodic multilayered structure, and the continuous growth of diamond grains is clearly observed. Raman spectroscopy, Rockwell hardness testing and nanoindentation analysis reveal that coatings with an optimized β-SiC phase content not only exhibit reduced residual stress (1.8 GPa) and enhanced adhesion (delamination rate reduced to 21.5 %), but also possess high hardness (80.6 GPa) and elastic modulus (1079.4 GPa). The influence of β-SiC phase on the coatings is primarily attributed to defect structures such as stacking faults (SFs) and twins (TBs) formed at the two-phase interface, which effectively hinders dislocation motion and thereby enhances the hardness and modulus of the coatings. Furthermore, the presence of SFs and TBs within the β-SiC phase improves its plastic deformation capability, enabling effective dissipation of strain energy induced by the diamond coating and reducing the overall residual stress of the coating. This study provides critical insights into the design and optimization of multilayered diamond/β-SiC composite coatings, facilitating their advanced application in cutting-edge tool coating technologies.