Fabrication, microstructure, and mechanical properties of novel three‐layer structured bionic ceramic cutting tools

Abstract

Ceramic cutting tools have low fracture toughness owing to brittleness. To improve the fracture toughness and flexural strength of ceramic cutting tools, the growth model of SiCw during the sintering process was established by the laminated structure and anisotropy of growth of bionic shells. Furthermore, a theoretical model of sintering parameters and total fracture toughness was achieved. Then, the dispersion process of SiCw was improved to enhance the homogeneity of the mixed powders further. Finally, a novel three‐layer structured bionic ceramic cutting tool was fabricated by hot‐pressing. The effects of sintering temperature, holding time, and sintering pressure on the mechanical properties and microstructure of bionic ceramic cutting tools were investigated. The results showed that the flexural strength (three point bending), fracture toughness (indentation method), and Vickers hardness of the three‐layer structured bionic ceramic cutting tool with excellent dispersed were 735 ± 34 MPa, 5.68 ± 0.06 MPa·m1/2, and 19.66 ± 0.12 GPa, respectively. The microstructure of the fracture revealed that the fracture mechanism of the bionic ceramic cutting tool was a mixture of intergranular fracture, transgranular fracture, whisker pull‐out, whisker fracture, forked crack, crack deflection, crack bridging, zig‐zag crack, and crack termination. The accuracy of the total fracture toughness model was reliable.