Effect Of Cvd-Sic Interface Modification Coating On The Mechanical Properties Of C-F/Sic Composite Prepared By Gaseous Silicon Infiltration Process

The interface plays a key role on the mechanical properties of C-f/SiC composite prepared by GSI process. The ideal interface should not only prevent carbon fiber from being etched by Si vapor, but also adjust the bonding force between C fiber and SiC matrix. SiC coating prepared by CVD was chosen as the interface and its effect on the mechanical properties and fracture features of GSI C-f/SiC composite was discussed, and the influencing mechanism was analyzed. The results show that GSI C-f/SiC composite without CVD-SiC interface has poor mechanical properties, exhibiting brittle fracture feature. The bending strength, elastic module and fracture toughness are 87. 6MPa, 56. 9GPa and 2. 1MPa . m(1/2) , respectively. The mechanical properties of GSI C-f/SiC increase with the increase of the thickness of CVD-SiC coating at first, then decrease with the continuous increase of the thickness of CVD-SiC coating. The C f /SiC composite with 1. 1 mu m thickness of CVD-SiC coating has the best mechanical properties, and the bending strength, elastic module and fracture toughness are 231. 7MPa, 87. 3GPa and 7. 3MPa . m(1/2), respectively. The action mechanism of CVD-SiC interface coating on the composite is mainly on the three aspects : load transfer, preventing C fiber from being etched by Si and adjusting fiber/matrix bonding status.