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

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 degrees 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 degrees C. However, the flexural strength of asprepared composites after heat treat at 1800 degrees C was maintained at 153 MPa, which was lower than that of the in-situ flexural test at 1800 degrees C, because the fibers were more seriously eroded after heat treatment at 1800 degrees C. After heat treatment at 2400 degrees 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 degrees 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 degrees C-2400 degrees C. (C) 2019 Elsevier B.V. All rights reserved.