High-temperature mechanical properties and microstructure of C/C‒ZrC‒SiC‒ZrB2 composites prepared by a joint process of precursor infiltration and pyrolysis and slurry infiltration

Abstract

C/C–ZrC–SiC–ZrB2 composites were prepared by a joint process of precursor infiltration and pyrolysis and slurry infiltration. The high-temperature mechanical properties of the composites were reported and the evolution of fracture behavior and microstructure was analyzed. The composites exhibited a tensile strength and flexural strength of 99.3 MPa and 281 MPa, respectively during the test at ambient temperature. The high temperature in-situ tensile properties were higher than those at ambient temperature; the tensile strength was 136 MPa during the tensile test at 1700 °C. This is because the energy absorption mechanisms will occurred during the high-temperature test. The high temperature in-situ flexural strength was 223 MPa during flexural test at 1800 °C. However, the flexural strength of as-prepared composites after heat treat at 1800 °C was maintained at 153 MPa, which was lower than that of the in-situ flexural test at 1800 °C, because the fibers were more seriously eroded after heat treatment at 1800 °C. After heat treatment at 2400 °C, the flexural strength of the composites decreased to 88 MPa. It can be inferred that the high temperature in-situ flexural strength at 2400 °C was higher than 88 MPa, showing outstanding ultra-high temperature mechanical properties. Therefore, the C/C–ZrC–SiC–ZrB2 composites are promising to be applied as structural material in aerospace, due to their excellent high-temperature mechanial properties at 1500 °C–2400 °C.