Effects of processing temperature on microstructures and mechanical behaviours of reactive hot-pressed SiC(SCS-6)/Ti/ZrB2-ZrC hybrid composites

In this study, hybrid composites comprising SiC(SCS-6)/Ti composite and ZrB2-ZrC ceramics were prepared by sandwiching Ti/SiC(SCS-6)/Ti sheets and Zr + B4C powder layers, followed by reactive hot pressing (RHPing) between 1250 °C and 1400 °C. The effects of RHPing temperature on the microstructures and the mechanical behaviours of the composites were examined. For the samples prepared at 1250 °C and 1300 °C, a Ti-rich zone was observed in the matrix and around the fibres. However, for the sample prepared at 1400 °C, no Ti-rich zone was observed. In addition, the hybrid composites show noncatastrophic fracture behaviour, irrespective of RHPing temperature. Compared to the sample processed at 1400 °C, the samples processed at 1250 °C and 1300 °C exhibited higher flexural strength and greater damage tolerance. The lower strength and damage tolerance for the composite processed at 1400 °C are attributed to stronger interface bonding via significant degradation of the C-rich coating and to strength degradation of the fibres.