Preparation and mechanical properties of jute fiber knit-derived SiC composites prepared by Si slurry infiltration

Bioinspired SiC composites have great potential applications in fields such as electromagnetic shielding, catalytic filtration, aerospace, etc. The jute fiber knit-derived C-SiC composites were successfully prepared by slurry impregnation method combined with two densification routes (route 1: impregnation with carbon powders slurry, route 2: impregnation with PCS (polycarbosilane) slurry) were used to further densify the composites. Effects of impregnation times, sintering temperatures and densification routes on the microstructures and mechanical properties of the composites were investigated in details. The compressive strength of composites increased from 1.6 ± 0.2 MPa to 2.8 ± 0.4 MPa, with the sintering temperatures increasing from 1400 °C to 1600 °C. This might result from the higher crystallinity of SiC formed in composites at 1600 °C. The composites prepared by densification route 1 exhibited the highest compressive strength of 7.1 ± 1.7 MPa, which was ∼253.6 % higher than the non-densified composites (2.8 ± 0.4 MPa). This might result from a small porosity, a thick silicon carbide layer (0.8–1.1 μm) and particles formed in composites, leading to reinforcement. In addition, the composites sintered at 1600 °C exhibited an increased compressive strength by ∼219.2 % (from 2.6 MPa to 8.3 MPa), after high-temperature oxidation at 1400 °C. The flexural strength of composites increased from 2.5 ± 0.2 MPa to 4.2 ± 0.5 MPa, with the sintering temperatures increasing from 1400 °C to 1600 °C. This might result from the high crystallinity of SiC formed, leading to the crack deflection. The composites prepared by densification route 2 showed the highest flexural strength of 10.6 ± 1.3 MPa, which was ∼252.4 % higher than the non-densified composites (4.2 ± 0.5 MPa). Therefore, the combination of slurry impregnation and densification routes provides a viable route to improve the mechanical properties of the composites.