Mingde Tong,Xinhao Shi,Tao Feng,Ying Dai,Pengfei He
To achieve the repeatability of aerospace thermal components, C/TaC‒SiC composites were fabricated. Cycle ablation and bending tests were carried out. After 3 × 60 s of ablation beyond 2100°C, the mechanical property retention rate was 80.9%. Interestingly, a reaction similar to “ouroboros ring,” in which the cyclic reactions of “TaC being oxidized to Ta 2 O 5 and Ta 2 O 5 being reduced to TaC,” occurred in the central ablation region of C/TaC‒SiC composites. On the one hand, the continuous generation of TaC could prevent liquid state Ta 2 O 5 from being blown off central ablation region, playing a similar role in “water and soil conservation.” On the other hand, liquid Ta 2 O 5 covered the surface of C/TaC‒SiC composites during ablation process, contributing to block the inward permeation of oxidized gases. In addition, novel “Grotto” structures were detected in the transitional ablation region of C/TaC‒SiC composites. The formation reason of the “Grotto” structure has also been discussed.
Thermal protection systems of hypersonic vehicles typically require advanced high-temperature materials capable of withstanding long-term exposure to oxidizing environments at 1800–2500 °C. However, related studies are scarce. Here, by employing a laser-assisted compositional engineering strategy, we successfully explore innovative high-entropy alumino-silicides (HEASs) that show superior long-term oxidation resistance across 1700–2100 °C for 80 min in air, surpassing the performance of previously reported ultrahigh-temperature materials. The oxidation resistance of HEASs is further validated by plasma ablation testing in air, exhibiting a linear ablation rate of as low as 0.035 μm·s –1 at 2100 °C. Such remarkable oxidation resistance is attributed to the formation of a unique alumino-silicate glassy phase. Further first-principles calculations coupled with experimental observations indicate an ultralow oxygen diffusion rate (4.26 × 10 –5 cm 2 ·s –1 ) and exceptional thermal stability (binding energy of –0.004 eV·A –2 ) in the alumino-silicate glassy phase due to multi-component synergistic effects. This work highlights the potential of HEASs for long-term ultrahigh-temperature applications.
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