Abstract Modern hybrid rockets are susceptible to the highly ablative environment in which they operate, as introducing an adequate cooling system has so far been a challenge. Ablative material has been widely adopted for use in hybrid rockets, which can only survive for the limited operation time. The use of ablative materials such as pyrolytic composite or graphite is advantageous for use in a simple system in an uncooled state. However, ablation causes severe enlarging in the nozzle throat area and a significant drop in the pressure during operation. Recently, Ultra High-Temperature Ceramics (UHTCs) have been noted as superior in terms of ablation and oxidation resistance. The most promising HfC-SiC composite ceramic has demonstrated an enhanced performance for thermal and mechanical properties. In this study, an HfC-SiC composite was embedded in the graphite casing as a nozzle insert throat to analyze the feasibility of its application in rockets. An experimental analysis of the ablation in the HfC-SiC was carried out with a 250 N scale hybrid thruster using High Test Peroxide (HTP) and High-Density Polyethylene. The hot-fire condition was set to above 30 bar for 25 s combustion, with the purpose of producing significant erosion on the nozzle materials. The graphite nozzle of the same shape was also tested under the same experimental conditions for comparison of the erosion. The hot-fire test with the HfC-SiC insert resulted in a stable rocket performance, with improvements to the chamber pressure and the thrust, whereas the combustion performance varied undesirably in the test using the graphite nozzle due to ablation. The rate of ablation in the throat was significantly reduced to 15.81 μm/s using HfC-SiC, which is 46.5% of the erosion rate found in the graphite. The adoption of the HfC-SiC composite effectively inhibited the ablation on the throat. However, substantial erosion occurred on the interfaces due to the different ablation resistances. The feasibility of adopting hafnium-based carbide on the rocket was also evaluated based on a material analysis of the surface oxidation.

中文翻译：

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HfC-SiC耐火陶瓷复合材料火箭喷管烧蚀特性

摘要 现代混合火箭很容易受到它们运行的​​高度烧蚀环境的影响，因为引入足够的冷却系统迄今为止一直是一个挑战。烧蚀材料已广泛用于混合火箭，其只能在有限的运行时间内存活。使用诸如热解复合材料或石墨的烧蚀材料有利于在未冷却状态下在简单系统中使用。然而，烧蚀会导致喷嘴喉部区域严重扩大，并在操作过程中导致压力显着下降。最近，人们注意到超高温陶瓷 (UHTC) 在抗烧蚀性和抗氧化性方面表现出色。最有前途的 HfC-SiC 复合陶瓷已显示出增强的热性能和机械性能。在这项研究中，将 HfC-SiC 复合材料嵌入石墨外壳中作为喷嘴插入喉部，以分析其在火箭中应用的可行性。使用高测试过氧化物 (HTP) 和高密度聚乙烯，使用 250 N 规模的混合推进器对 HfC-SiC 中的烧蚀进行了实验分析。热火条件设置为 30 bar 以上，燃烧 25 秒，目的是对喷嘴材料产生显着的侵蚀。相同形状的石墨喷嘴也在相同的实验条件下进行了测试，以比较侵蚀。使用 HfC-SiC 插件进行的热火测试产生了稳定的火箭性能，并改善了腔室压力和推力，而在使用石墨喷嘴的测试中，由于烧蚀，燃烧性能发生了不理想的变化。使用 HfC-SiC，喉部的烧蚀速率显着降低至 15.81 μm/s，这是石墨中侵蚀速率的 46.5%。HfC-SiC复合材料的采用有效抑制了喉部的烧蚀。然而，由于不同的消融阻力，界面上发生了大量侵蚀。还基于对表面氧化的材料分析，评估了在火箭上采用铪基碳化物的可行性。