Effect of ZrC amount and distribution on the thermomechanical properties of Cf/SiC-ZrC composites

C-f/SiC-ZrC composites with different amounts and distributions of ZrC were fabricated by polymer impregnation and pyrolysis. The effects of the ZrC amount and distribution on the microstructural, mechanical, and ablation properties of C-f/SiC-ZrC composites were investigated. C-f/SiC-ZrC composites obtained by the alternating infiltration of ZrC organic precursors and polycarbosilane groups exhibit good tensile strength (240 +/- 17.7 MPa) because the ZrC and SiC matrix can mix evenly. However, C-f/SiC-ZrC composites using only ZrC organic precursor infiltration show a low tensile strength (191 +/- 16.6 MPa) because more defects can be introduced into the composites. Ablation characterization by a 30 kW plasma wind tunnel for 60 seconds showed that the C-f/SiC-ZrC composites with the highest amount of ZrC matrix (67.8 wt.%) possessed the lowest linear erosion rate of 4 mu m/s because liquid SiO2 could fill the porous ZrO2 to form a homogenous protective layer. Nevertheless, the C-f/SiC-ZrC composites with a relatively high ZrC amount (55.3 wt.%) exhibited a poorer ablation performance compared to that of C-f/SiC-ZrC composites with a low ZrC amount (38.7 wt.%).