Improvement of mechanical properties of bio-inspired layered Si3N4/BN ceramics

Abstract

The applications of Si3N4 ceramics are hindered by their brittleness and susceptibility to fracture, despite their high strength and wear resistance. To address this challenge, layered ceramics were prepared using lamination and plasma sintering techniques, inspired by the structure of shell pearl layers. The bio-inspired layered ceramics were alternately arranged with Si3N4 as the matrix layer (hard) and BN as the interfacial layer (soft). During the study, ceramic specimens with different microstructures were obtained by modulating the layer thickness ratio (ratio of Si3N4 to BN) and sintering temperature. The microstructure of the specimens was characterized using SEM (Scanning Electron Microscope) and EDS (Energy Dispersive Spectrometer). The mechanical of various specimens were assessed by measuring the flexural strength and fracture toughness. The results of the investigation revealed that the mechanical characteristics of the samples reached their optimum state (with a toughness of 13.51 ± 1.56 MPa m1/2 and a strength of 429 ± 4.28 MPa) when the ratio of Si3N4 to BN was 5:1, and the sintering temperature was maintained at 2000 °C.