Microstructure and mechanical properties of C/C-ZrC composites

C/C-ZrC composites were obtained by subsequent steps: immersing carbon felts into ZrOCl₂ aqueous solution, heat treatment, densification by thermal gradient chemical vapor infiltration with methane gas and graphitization. Three-point bending tests were performed to evaluate the mechanical properties of the composites. The results show that the flexural strength and elastic modulus increase with increasing ZrC contents. Carbon/carbon (C/C) composites containing 12.08wt% ZrC achieve a flexural strength of 42.5 MPa and a modulus of 9.6 GPa, increasing by 70.0% and 43.3%, respectively, as comparison with the flexural strength and modulus of C/C composites. Micro-size ZrC particles with weak anchoring strength between them are unfavorable to the strength of carbon matrices, but they are not the main determinant of the strength of the composites. Submicro- and nano-size ZrC particles in carbon matrices owning good interface anchoring strength with carbon matrices can enhance the strength and elastic modulus of carbon matrices, improving the final mechanical properties of the composites.