In-situ preparation and mechanical property analysis of SiC/SiBCN(O) nanocomposites

In this paper, the dense SiC/SiBCN(O) nanocomposite without obvious crack and/or void was prepared by employing SiBCN(O) amorphous ceramics as starting material. Via controlling heat treatment time of the raw material at 1400 °C, nano β-SiC grains were in situ generated and uniformly dispersed within the amorphous SiBCN(O) ceramic matrix, and the target materials were thus obtained, which may provide a new strategy for fabricating the dense SiBCN(O) based nanocomposties. The influence of dwelling time on chemical composition, grain precipitation and mechanical properties of the materials were also investigated. The experimental results showed that the prepared SiC/SiBCN(O) nanocomposite was dense and pore/crack free, and with the increase in holding time at 1400 °C, the chemical composition of the materials became more uniform and its mechanical properties were significantly improved as well. Particularly, after holding at 1400 °C for 8 h,a number of β-SiC particles with an average size of 28 nm were in-situ precipitated and homogeneously dispersed in the amorphous SiBCN(O) matrix, compared with their counterpart experienced 2 h heat treatment, its nano-hardness, micro-region elastic modulus, flexural stress and elastic modulus were enhanced from ~5 GPa, ~50 GPa, ~40 MPa and ~10.7 GPa, to ~25 GPa, ~190 GPa, ~145 MPa and ~22 GPa, respectively.