Effects of pyrolysis processes on microstructure and mechanical properties of Cf/SiOC composites fabricated by preceramic polymer pyrolysis

The mechanical properties and densities of 3D-B Cf/SiOC composites could be remarkably increased if the first pyrolysis was assisted by hot-pressing. When the first pyrolysis was conducted at 1600 °C for 5 min with a pressure of 10 MPa, the resultant composites showed 502 MPa in flexural strength and 23.7 MPa m1/2 in fracture toughness while the composites fabricated without the assistance of hot-pressing showed only 246.2 MPa in flexural strength and 9.4 MPa m1/2 in fracture toughness. The high mechanical properties were mainly attributed to desirable interfacial structure and high density.