Microstructure and mechanical properties of carbon/carbon composites with PyC/SiC/TiC multilayer interphases

Carbon/carbon composites with PyC/SiC/TiC multilayer interphases (CCs-PST) have been successfully prepared by a joint process of chemical vapor deposition and carbothermal reduction. Effect of the Ti(OC₄H₉)₄/C₆H₄(OH)₂ molar ratio on the morphology of TiC particles was investigated and the ratio was optimized as 8:1. When the Ti(OC₄H₉)₄/C₆H₄(OH)₂ molar ratio was 8:1, many homogeneously distributed TiC nanoparticles with the sizes of 100–500 nm on the fibers were observed. The structural evolution of CCs-PST was discussed and the mechanical properties of as-prepared materials were investigated by flexural and interlaminar shear tests. The resulted composites demonstrated a PyC and SiC mixed inner interphase with the thickness of 0.5–1 μm and a TiC outer interphase with a thickness about 0.5 µm. Flexural strength of 201.45 ± 5.27 MPa and modulus of 21.21 ± 1.58 GPa showed a 41.7% and 7.83% improvement respectively as compared with that of the neat CCs. The interlaminar shear strength of CCs-PST was 66.71 ± 4.87 MPa, which was 51.20% higher than that of the CCs. The improved mechanical properties were attributed to the enhanced interface bond between fibers and matrix induced by the PST.