Microstructure and mechanical properties of C/C composites modified by single-source precursor derived ceramics

To improve the mechanical properties of C/C composites, the SiC(N)/TiC ceramic derived from single-source precursors (SSPs) were introduced into the C/C by precursor infiltration and pyrolysis (PIP) at 1100 degrees C. The shear strength of all modified composites were improved by nearly 2 times compared with the pristine C/C composites (37.4 MPa) due to the increased interfaces by multiphases incorporation. After further annealing at 1500 degrees C, the SiC(N)/TiC ceramic in C/C composite transferred into the nanocomposites, SiC(N)/TiC-NCs, in which nano-scale TiC particles distributed into the SiC(N) matrix. The modified samples still exhibited about 39% improvement on shear strength. Large numbers of uniform micro-cracks occurred in both above SSPs derived ceramic cases, reducing stress concentration during the shear testing. Moreover, some ring-shaped cracks were observed in the fracture region which can consume large amounts of energy in crack propagation process and then benefit to improve the shear strength.

Automated summary

By using precursor infiltration and pyrolysis, SiC(N)/TiC ceramics derived from single-source precursors were introduced into C/C composites, significantly improving the shear strength. After annealing, the ceramics transformed into SiC(N)/TiC-NCs nanocomposites, further enhancing the shear strength.