Fabrication and characterization of pyrolytic carbons from phenolic resin reinforced by SiC nanowires with chain-bead structures

摘要

SiC/SiO2 nanowires (NWs) were successfully synthesized via a simple chemical vapor deposition method at 1200 degrees C under an argon atmosphere by using phenolic resin (PF) and silicon (Si) and then catalyzed by copper citrate. The obtained SiC/SiO2 NWs as-calcined at 1200 degrees C had a chain-bead structure, and the SiC nanowire was wrapped by amorphous SiO2 nanospheres: The diameter of the SiO2 bead was in the range of 175-250 nm; the length of the SiC chain was 375-500 nm, and the diameter was 83 nm. The copper phase derived from copper citrate could dissolve with Si to form a Cu/Si alloy, and it could reduce the melting point of the Si particle and generate higher amount of SiO. The growth mechanism of the Cu-catalyzed SiC/SiO2 NWs was vapor-solid (V-S). The strength and oxidation resistance of the PF pyrolysis carbons were reinforced by SiC/SiO2 NWs. The cold crushing strength (CCS) of the PF pyrolysis carbons calcined at 1200 degrees C and 1300 degrees C increased from 0.08 MPa to 0.64 MPa and 0.36 MPa to 1.81 MPa, respectively. The starting and ending temperatures of weight loss temperatures of PF pyrolysis carbons were delayed from 513 degrees C and 678 degrees C to 568 degrees C and 723 degrees C, respectively. The enhancements in the mechanical properties and oxidation resistance properties of the PF pyrolysis carbons were because the C-SiC bonding phase of the PF resisted external stress and oxygen effectively.