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 100–500nm 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 0.5–1μm and a TiC outer interphase with a thickness about 0.5µm. Flexural strength of 201.45 ± 5.27MPa and modulus of 21.21 ± 1.58GPa 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 ± 4.87MPa, 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.