Ablation behavior and mechanism of (PyC-Csf)/ZrB2-SiC-ZrC ceramics sintered by reactive spark plasma sintering at low temperature

The (PyC-C-sf)/ZrB2-SiC-ZrC ceramics are fabricated by reactive spark plasma sintering (RSPS) at 1200 degrees C. The sample has a low density and intact pyrolytic carbon modified carbon fiber (PyC-C-sf). After three cycles of ablation (heat flux = 2.38 MW/m(2), t = 120 s), samples demonstrate excellent resistance to oxidative ablation. The mass recession rate and linear recession rate for the sample are 3.41 g/m(2)center dot s and 0.68 mu m/s, respectively. Excessive content of carbon destroys the oxide layer by forming large amounts of CO2 during the ablation process. The inner layer of intact PyC-C-sf aggregates around the borosilicate which are denser in the oxide layer. Finally, a porous ZrO2-SiO2 layer and a dense ZrO2-SiO2-C-sf layer are formed on the surface of the sample which resists ablation.