Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University
Keywords:
-
CLC:
PACS:
-
DOI:
10.7502/j.issn.1674-3962.2016.02.06
DocumentCode:
Abstract:
In this study, two different densities of carbon/carbon (C/C) composites modified by SiC were prepared using reactive melt infiltration method (RMI). The phase composition, microstructure and element distribution of the asprepared composites were characterized by Xray diffraction (XRD) and scanning electron microscope (SEM). The oxidation resistance and thermal shock resistance of C/CSiC composites were investigated, and the morphology changes of the C/CSiC composites after oxidation test and thermal shock test were observed by SEM. The results show that the sizes of pores determined the infiltrating depth of the molten Si during RMI. The C/C1.0SiC composites had a low initial density with large sizes (10~100 μm), which was beneficial to infiltration of the molten melts and improvement of the final density. The oxidation behavior and thermal shock of C/CSiC composites were measured at 1500 ℃ in statics air. It indicated that C/C1.7SiC composites had a poor oxidation resistance and thermal shock resistance due to the coefficient of thermal expansion mismatch of SiC coating and C/C substrate. The mismatch would result in cracking or peeling and even failure of the coating. Nevertheless, C/C1.0SiC composites had a good oxidation resistance and thermal shock resistance because of the existence of multilayer interface between SiC matrix and C/C substrate, which effectively relieved the coefficient of thermal expansion mismatch of SiC matrix and C/C substrate. Therefore, the oxidation resistance and thermal shock resistance of C/C1.0SiC composites were improved significantly.