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Silicon oxycarbide composites reinforced by three-dimensional braided carbon fiber (3D-B C_f/Si-O-C) were fabricated via precursor infiltration and pyrolysis of polysiloxane, and the effects of processing variables on mechanical properties and microstructures of 3D-B C_f/Si-O-C composites were investigated. It is found that the mechanical properties and densities of 3D-B C_f/Si-O-C composites can be increased if the first pyrolysis cycle is assisted by hot-pressing. Pyrolysis temperature has great effects on mechanical properties and microstructures of 3D-B C_f/Si-O-C composites. The composite, which is hot-pressed at 1 600 ℃ for 5 min with pressure of 10 MPa in the first pyrolysis cycle, exhibits high mechanical properties: bending strength 502 MPa and fracture toughness 23.7 MPa·m~(1/2). The high mechanical properties are mainly attributed to desirable interfacial structure and high density.
Silicon oxycarbide composites reinforced by three-dimensional braided carbon fiber (3D-B C_f / Si-OC) were fabricated via precursor infiltration and pyrolysis of polysiloxane, and the effects of processing variables on mechanical properties and microstructures of 3D-B C_f / Si- OC composites were investigated. It is found that the mechanical properties and densities of 3D-B C_f / Si-OC composites can be increased if the first pyrolysis cycle is assisted by hot-pressing. Pyrolysis temperature has great effects on mechanical properties and microstructures of 3D-B C_f / Si-OC composites. The composite, which is hot-pressed at 1 600 ° C for 5 min with pressure of 10 MPa in the first pyrolysis cycle, exhibits high mechanical properties: bending strength 502 MPa and fracture toughness 23.7 MPa · M ~ (1/2). The high mechanical properties are mainly attributed to desirable interfacial structures and high density.