Ablation behaviors of ultra-high temperature ceramic composites

In order to improve the oxidation resistance of carbon fibers reinforced carbon matrix composites (C/C) and the thermal shock resistance of ultra-high temperature ceramics (UHTCs), large numbers of ZrB2 based particles were introduced into C/C composites to fabricate the C/C-UHTC composites by powder infiltration (PI) and isothermal chemical vapor infiltration (ICVI). The effects of UHTC additive, heat flux and ablation time on the ablation behaviors of the C/C-UHTC composites were investigated through exposure to an oxyacetylene torch flame with ultra-high temperature. The ZrB2 addition to the C/C pronouncedly improved the ablation resistance of the material under a 3920 kW/m2 heat flux and the C/C-ZrB2 showed a better ablation-resistive property compared to the C/C-4ZrB2-1SiC, C/C-2ZrB2-1SiC, C/C-2ZrB2-1SiC-1HfC and C/C-2ZrB2-1SiC-1TaC. With decrease of the heat flux from 3200 to 2380 kW/m2, the presence of a small amount of SiC in the C/C-ZrB2 was found to have a positive role of improving the ablation resistance; the C/C-4ZrB2-1SiC exhibited a good ablation-resistive endurance under 2380 kW/m2. The HfC addition was proved to effectively enhance the ablation property of the C/C-1ZrB2-2SiC while the TaC addition severely deteriorated the property.