基于原位自生HfyTa1-yC@C核壳结构的SiC-HfyTa1-yC-C纳米陶瓷微结构调控与性能研究

Ultra-high temperature ceramics (UHTCs) are indispensable as one of the potential strategic materials in the field of hypersonic flights. Regarding the brittleness and poor oxidation resistance of the UHTCs, novel single source precursors to Hf/Ta-Si-based ceramics will be synthesized in the present project proposal. Finally, fully dense SiC-HfyTa1-yC-C ceramic nanocomposites with in-situ formed HfyTa1-yC@C core-shell nanoparticles will be fabricated by combination of a polymer-derived ceramic (PDC) route with spark plasma sintering (SPS) technique. The main points of present project proposal are as follows: (1) ceramic microstructure will be tailored by tuning molecular structure of single-source-precursors. Especially, in order to improve fracture toughness of the final ceramic nanocomposites, the thickness of in situ formed carbon shell and amount of graphene-like carbon ribbons will be tuned to get self-toughing and improve mechanical properties and thermal shock resistance of final ceramics. (2) In order to improve the oxidation resistance of the resultant SiC-HfyTa1-yC-C nanocomposites, in situ formation of HfSiO4 protection phases after oxidation at a relatively low temperature of 1300℃, will be improved by tuning molar ratio of Hf/Ta in precursors. Formation mechanism and key factors of the HfSiO4 phase will be investigated. (3) The mechanical properties and high-temperature oxidation resistance of SiC-HfyTa1-yC-C ceramic nanocomposites will be systematically investigated. (4) Finally, a deep understanding of the interrelationships between polymer architecture and composition-nano/microstructure-intrinsic properties of the resultant ceramics will be acquired. In this project, the fully dense SiC-HfyTa1-yC-C ceramic nanocomposites with in-situ formed HfyTa1-yC@C core-shell nanoparticles can be used as high temperature components of hypersonic flight vehicles, and the single-soure-precursors are promising raw materials used for matrix modification, oxidation resistant coating and ablation resistant coating of Cf/C, Cf/SiC and SiCf/SiC ceramic composites.

超高温陶瓷是高超声速飞行不可或缺候选材料。针对其固有脆性和抗氧化性差的问题，本项目通过先驱体分子结构创新设计，拟合成Hf/Ta-Si一体化单源聚合物先驱体，结合PDC-SPS法制备致密、含原位自生HfyTa1-yC@C核壳结构的SiC-HfyTa1-yC-C纳米陶瓷。拟研究：（1）通过聚合物先驱体可控合成，调控纳米复相陶瓷微结构（原位自生碳壳层尺寸、碳带含量）实现自增韧，提高力学和抗热冲击性能；（2）调控陶瓷的Hf/Ta比例，促进其氧化产物在1300℃形成HfSiO4新相提高抗氧化性能，掌握其形成机理及影响因素；（3）纳米复相陶瓷力学性能和高温抗氧化性能影响规律；（4）建立“聚合物分子结构－陶瓷组成与微结构－陶瓷性能”的科学联系。本项目研制的超高温纳米复相陶瓷可用作相关构件，聚合物先驱体可用作Cf/C, Cf/SiC, SiCf/SiC基体改性和表面抗氧化、抗烧蚀涂层关键原材料。

超高温陶瓷是高超声速飞行不可或缺候选材料。本项目针对其固有脆性和抗氧化性差的问题，通过先驱体分子结构创新设计，成功地设计、合成Hf/Ta-Si一体化单源聚合物先驱体，结合PDC-SPS法制备致密、含原位自生HfyTa1-yC@C核壳结构的SiC-HfyTa1-yC-C纳米陶瓷。开展了如下研究：（1）通过聚合物先驱体可控合成，调控纳米复相陶瓷微结构（原位自生碳壳层尺寸、碳带含量）实现自增韧，提高力学性能；（2）调控陶瓷的Hf/Ta比例，促进其氧化产物在1300℃形成HfSiO4新相提高抗氧化性能，掌握了其形成机理及影响因素；（3）系统研究纳米复相陶瓷力学性能和高温抗氧化性能，并掌握了其影响规律；（4）建立“聚合物分子结构－陶瓷组成与微结构－陶瓷性能”的科学联系。本项目研制的超高温纳米复相陶瓷可用作相关构件，聚合物先驱体可用作Cf/C, Cf/SiC, SiCf/SiC基体改性和表面抗氧化、抗烧蚀涂层关键原材料。