Microstructure and properties of C/C-ZrC composites with matrix modification by slurry infiltration

C/C-ZrC composites are promising thermal structural materials for aerospace applications. However, until now, the reported C/C-ZrC composites exhibited a porous matrix and weaker mechanical properties. In this study, the matrices of C/C-ZrC composites were modified by slurry infiltration in order to improve density and properties. Different slurry powders such as SiC, ZrC, and ZrB2 were used to densify the C/C-ZrC composites. After slurry infiltration, the loose C-ZrC matrix was connected to a dense matrix, and some ceramic powders settled on the surface of the composites. The density of the composites increased from 1.94 to 2.42 +/- 0.06 g cm-3, while the porosity decreased from 39.4 +/- 4.4% to 10.3 +/- 1.9% after infiltration with various slurries. The ablation and mechanical properties of the C/C-ZrC composites improved significantly by matrix modification. The flexural strength of the composites increased from 116 to 269 +/- 21 MPa after slurry infiltration. Furthermore, the ablation properties of C/C-ZrC composites infiltrated with the ZrB2 slurry showed the lowest linear rate (24.7 mu m s-1) and mass recession rate (7.5 mg s-1).

Automated summary

In this study, the matrices of C/C-ZrC composites were modified by slurry infiltration to improve their density and properties. Different slurry powders were used to densify the composites. The density of the composites increased, while the porosity decreased after infiltration. The ablation and mechanical properties of the composites improved significantly by matrix modification.