Microstructure, interfacial and mechanical properties of SiC interphase modified C/C-SiC composites prepared by reactive melt infiltration

Interfacial modification can effectively regulate the interfacial properties of ceramic matrix composites. This paper reports on the effect of SiC interphase thickness on the microstructure, interfacial and mechanical properties of C/C-SiC composites. As the SiC interphase thickness increased to 2 mu m, the flexural strength and modulus of the C/C-SiC composites increased up to 252 MPa and 40 GPa, an increase of 36 % and 40 %, respectively. Because the SiC interphase protected the carbon fibers from the corrosion of liquid silicon, thereby increasing the effective fiber volume fraction. Furthermore, the increased interfacial shear strength (IFSS) measured by the fiber push-in test improved the load transfer efficiency. Raman spectrum and transmission electron microscopy indicated that the damage process of the interface with high IFSS after the fiber push-in test showed fiber/pyrolytic carbon interface debonding, release of thermal residual stress, and larger upward rebound protrusion of carbon fibers without interface crushing.