Effect of CVD-SiC Interface Modification Coating on the Mechanical Properties of C_f/SiC Composite Prepared by Gaseous Silicon Infiltration Process

Abstract

The interface plays a key role on the mechanical properties of Cf/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 Cf/SiC composite was discussed, and the influencing mechanism was analyzed. The results show that GSI Cf/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·m1/2, respectively. The mechanical properties of GSI Cf/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 Cf/SiC composite with 1.1μm 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·m1/2, 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.

Keywords

• CVD SiC
• interface modification coating
• GSI
• C_f/SiC composite
• mechanical property