铝硅酸盐纤维增强莫来石复合材料的制备及其界面调控研究

Owing to high toughness, strength, modulus, inherent oxide resistance and excellent dielectric properties, continuous oxide fiber-reinforced oxide (oxide/oxide) composites, have been considered as one of the most important high-temperature structural and functional materials. However, performances of three-dimensinal (3D) oxide/oxide composites are mainly determined by the fabrication process and interfacial properties. Till now, these composites usually exhibit poor mechanical properties and short high-temperature serving time, which greatly limit their industrial applications. This proposal aims to develop high-performance 3D oxide/oxide composites based on the combination of process optimizing and interface engineering, and to investigate their high-temperature serving properties..This proposal will focus on exposing the relationship between the structure, properties of 3D aluminosilicate (AS) fiber-reinforced mullite (ASf/Mullite) composites and the content of mullite micro-powder, densification cycle, sintering temperature and other parameters according to the interface theory. Their interface features will be clarified by the combination of the fiber push-in test and TEM analysis. On this basis, mechanical properties of the composites will be further improved by interface engineering with FC/SiBN multi-interphases. Finally, thermal aging and fatigue properties of ASf/FC/SiBN/Mullite composites will be studied under serving conditions. The evolvement rule of their microstructure and mechanical properties will also be revealed. This project will greatly promote the controllable preparation of high-performance oxide/oxide composites and their high-temperature applications.

氧化物/氧化物复合材料具有高韧性、高比强度和高比模量，抗氧化性能和介电性能优异，是目前高温结构和功能材料研究的重要方向。然而，受制备工艺与界面特性的制约，三维氧化物/氧化物复合材料的力学性能普遍偏低，且高温服役时间较短，限制了其工业化应用。本项目旨在通过制备工艺优化结合界面调控的方法制备高性能三维氧化物/氧化物复合材料，并探索其高温服役性能。.本项目将从界面理论出发，重点研究三维ASf/Mullite复合材料结构、性能与莫来石微粉含量、致密化周期、烧结温度等工艺参数的对应关系；利用TEM结合纤维压入技术，揭示复合材料界面特性；在此基础上，引入FC/SiBN复合界面相进行界面调控，进一步提升力学性能；最后，开展ASf/FC/SiBN/Mullite复合材料高温老化、疲劳性能研究，揭示其微观结构与力学性能的演变规律。项目成果将极大地促进高性能氧化物/氧化物复合材料的可控制备与高温应用。

连续氧化物纤维增强氧化物复合材料性能优异，在高温结构领域具有广阔的应用前景，但是该类复合材料在可控制备与力学性能设计方面还存在较多问题，如制备大型复杂构件、力学性能提升、服役寿命保持等。本项目以铝硅酸盐纤维增强莫来石复合材料为研究对象，开展了复合材料的制备及其界面特性、纤维表面PyC/SiBN涂层的制备及其沉积机理，以及含界面相复合材料的制备及其微观结构与服役性能等方面研究工作。研究发现：热处理温度对复合材料的力学性能影响较大，浆料浸渗辅助Sol-Gel工艺能够显著缩短制备周期，1100℃、3个周期制备的复合材料力学性能较为优异；CVD工艺参数，如温度、气压、时间等，对纤维表面PyC和SiBN涂层的微观结构影响较大，900℃沉积涂层纤维的力学性能较为优异；PyC和SiBN界面相与纤维、基体的理化相容性较好，引入后可有效弱化复合材料中纤维/基体界面结合，进而提升力学性能；界面调控后复合材料在1300℃长时服役条件下力学性能降级不明显，抗疲劳性能较好，但抗热震性能一般。后续，将结合导弹天线罩等典型构件应用需求，系统开展性能设计、工程研制与服役性能研究工作。