No abstract

Carbon fiber reinforced ceramic matrix composites (C/C‐SiC composites) were fabricated using a type of high‐char‐yield phenolic resin with the char yield of 81.17 wt.%. Firstly, the fabric prepreg was prepared by spreading the phenolic resin solution onto the two dimensional carbon fiber plain weave fabric and dried consequently. Afterward, the resin was cured and then the carbon fiber reinforced polymer (CFRP) was pyrolyzed to get amorphous carbon. Finally, C/C‐SiC composites were obtained through liquid silicon infiltration (LSI) process. SEM micrographs showed that the Si/SiC area was homogeneously dispersed in the matrix, and during the siliconization process, a layer of SiC was formed along the surface of carbon fibers or carbon matrix. The fiber volume of CFRP was about 40 vol.%, which was much lower than other studies. XRD result indicated that only β‐SiC type was formed. The result of X‐ray computed tomography clearly showed the structure changes before and after the melt infiltration process. Mechanical property test showed that the composites had fracture strength of 186 ± 23 MPa, and a flexural modulus of 106 ± 8 GPa.

The SiC-Ti 3 SiC 2 -TiB 2 composites herein were prepared in situ by reactive melt infiltration (RMI). The synergy mechanism between Ti 3 SiC 2 and TiB 2 on fracture toughness of SiC matrix was investigated. The phase composition and microstructure of SiC-Ti 3 SiC 2 -TiB 2 composites were studied, and their mechanical properties, such as Vickers hardness, elastic modulus and indent fracture toughness, were compared to those of SiC ceramics and SiC-Ti 3 SiC 2 composites. The crack propagation of SiC-Ti 3 SiC 2 -TiB 2 composites was simulated via Extended Finite Element Method (XFEM), and the fracture behavior in laminated Ti 3 SiC 2 grains was also evaluated. The results show that SiC-Ti 3 SiC 2 -TiB 2 composites exhibit an indentation fracture toughness of 9.57 MPa m 1/2 , which is greatly higher than that of SiC ceramics and SiC-Ti 3 SiC 2 composites. It was suggested that the main toughening mechanisms of lamellar Ti 3 SiC 2 grains and columnar TiB 2 grains are crack deflection, crack bridging, grain fracture, delamination and grain pull-out.