Fabrication and mechanical properties of 3-D Cf/C-SiC-TiC composites prepared by RMI

In this paper, the three-dimensional needled carbon fiber reinforced C-SiC-TiC ceramic composites (C-f/C-SiC-TiC) were successfully fabricated by chemical vapor infiltration (CVI) and Ti, Si mixed powders (Si content is the eutectic point of the Ti-Si alloy, 9.2 w.t.%) reactive melt infiltration (RMI) process. The open porosity and bulk density were about 4.71% and 2.14 g/cm(3). The formation and distribution of the composites were investigated by XRD and EDS maps, and no residual Ti or Si phases were found. TiC and a layered SiC ceramics were formed in carbon fiber reinforced pyrolytic carbon (C-f/C) preforms due to the in situ reaction between pyrolytic carbon and Ti, Si powders. Their mechanical properties were improved compared with C-f/C-SiC composites. The flexural strength, flexural modulus and failure strains of the prepared composites were 218.44 +/- 16.23 MPa, 68.17 +/- 8.69 GPa and 2.22 +/- 0.12%, respectively. In addition, the C-f/C-SiC-TiC composites showed a pseudoplastic fracture behavior because of debonding and pullout of fibers as well as propagation and deflection of cracks. Furthermore, the enhanced mechanism of the composites was proposed. (C) 2019 Published by Elsevier B.V.