Improving mechanical properties of SiCw/SiC composite by phase content optimization via reactive melt infiltration

Inspired by the preparation methods of continuous fiber reinforced ceramic matrix composites (CFCCs), a novel silicon carbide whiskers (SiCw)-toughened SiC CMC with isotropic high strength and toughness, high density, and relatively low cost and short manufacturing cycle is prepared by a combination of gel-casting (GC) and reactive melt infiltration (RMI). The content and degree of graphitization of resin carbon during RMI are altered by annealing the SiCw/C mixture and adjusting the amount of SiCw to optimize phase composition and improve the mechanical properties of SiCw/SiC composites. The results reveal that the content of SiC phase is directly related to the flexural strength, reaching a maximum value of 339 MPa at 83 vol%. Also, the increase in C content increases the fracture toughness, reaching a value of 6.2 MPa m1/2 at carbon content of 4.6 vol%. The toughening of SiCw/SiC composites is realized by SiCw toughening, residual SiCw/C toughening and SiC particle toughening.