2.5-dimension SiC_f/SiC composites fabricated by low pressure chemical vapor infiltration

2.5-dimension continuous silicon carbide fiber reinforced silicon carbide composites (SiC_f/SiC) on the interface with and without a pyrocarbon layer were fabricated by low pressure chemical vapor infiltration. The volume fractions of SiC fiber were 30% and 41%. The porosity of the fabricated composites was about 20%. The flexural strength of the SiC_f/SiC composite with 30% fiber and having an interface pyrocarbon layer about 0.1μm thick increased from 232 MPa to 328 MPa and the fracture behavior changed from catastrophic failure to non-catastrophic failure compared with the composite without the pyrocarbon layer. The porosity of the composite slightly increased with the increase of fiber volume fraction from 30% to 41% when the fabrication process conditions were same. The flexural strength of SiC_f/SiC with 41% fiber and an interface layer about 0.1μm thick was only 244 MPa, but the fracture toughness was greater and the length of fiber pull-out was longer.