Fabrication and mechanical properties of boron nitride nanotube reinforced boron carbide ceramics

抄録

A series of boron nitride nanotubes (BNNTs)/ boron carbide (B₄C) composite ceramics were prepared using spark plasma sintering (SPS) technology, which uses B₄C powders as the matrix and BNNTs as the toughening phase. X-ray diffraction (XRD) and scanning electron microscope (SEM) were then used to characterize the B₄C ceramic samples. The effects of the sintering temperature, the BNNTs content, and the matrix particle size on the microstructure and mechanical properties of the B₄C composite ceramics were investigated in detail. The experimental results showed that the ceramic samples obtained by adding a 5 wt % BNNTs content sintered at 1750 °C displayed the best mechanical properties. The relative density, microhardness, and fracture toughness were 99.41 %, 32.68 GPa, and 6.87 Mpa·m^1/2, respectively. The fracture toughness was 54.59 % higher than that of the composite without the BNNTs. The toughening mechanism of the BNNTs was also studied. The pulling-out of the BNNTs, bridging, and crack branch contributed to the toughness property of the B₄C-based ceramic.