Microstructure and mechanical properties of hot-pressed SiC nanofiber reinforced SiC composites

This study reports on the preparation and mechanical properties of a novel SiC nf /SiC composite. The single crystal SiC nanofiber(SiC nf ) reinforced SiC ceramic matrix composites (CMC) were successfully fabricated by hot pressing the mixture of β -SiC powders, SiC nf and Al–B–C powder. The effects of SiC nf mass fraction as well as the hot-pressing temperature on the microstructure and mechanical properties of SiC nf /SiC CMC were systematically investigated. The results demonstrated that the 15 wt% SiC nf /SiC CMC obtained by hot pressing (HP) at 1850 °C with 30 MPa for 60 min possessed the maximum flexural strength and fracture toughness of 678.2 MPa and 8.33 MPa m 1/2 , respectively. The nanofibers pull out, nanofibers bridging and cracks deflection were found by scanning electron microscopy, which are believed can strengthen and toughen the SiC nf /SiC CMC via consuming plenty of the fracture energy. Besides, although the relative density of the prepared SiC nf /SiC CMC further increased with the sintering temperature rose to 1900 °C, the further coarsend composites grains results in the deterioration of the mechanical properties for the obtained composites compared to 1850 °C.