Comparison of thermal and ablation behaviors of C/SiC composites and C/ZrB2–SiC composites

A comparison was presented of the thermal and ablation behaviors of two carbon fiber reinforced ceramic–matrix composites (one with a SiC matrix and the other with a ZrB2–SiC matrix). The C/SiC composite possessed a lower thermal conductivity (TC) and a higher emissivity in comparison to the C/ZrB2–SiC composite. The two composites exhibited the good ablation-resistive properties with no obvious erosion rate after the arc-heated wind tunnel ablation tests. The surface of the C/SiC composite appeared to be coarse and had many rounded protrusions while a denser and more homogeneous glass oxide scale was formed for the C/ZrB2–SiC composite. The maximum surface and back side temperatures of the C/ZrB2–SiC composite were about 50 °C lower than those of the C/SiC composite, respectively, which was mainly attributed to the evaporation of the B2O3 as well as its higher TC.